| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 1 | <html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Git User's Manual (for version 1.5.3 or newer)</title><link rel="stylesheet" href="docbook-xsl.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.69.1"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="book" lang="en"><div class="titlepage"><div><div><h1 class="title"><a name="id189136"></a>Git User's Manual (for version 1.5.3 or newer)</h1></div></div><hr></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="preface"><a href="#id264725">Preface</a></span></dt><dt><span class="chapter"><a href="#repositories-and-branches">1. Repositories and Branches</a></span></dt><dd><dl><dt><span class="section"><a href="#how-to-get-a-git-repository">How to get a git repository</a></span></dt><dt><span class="section"><a href="#how-to-check-out">How to check out a different version of a project</a></span></dt><dt><span class="section"><a href="#understanding-commits">Understanding History: Commits</a></span></dt><dd><dl><dt><span class="section"><a href="#understanding-reachability">Understanding history: commits, parents, and reachability</a></span></dt><dt><span class="section"><a href="#history-diagrams">Understanding history: History diagrams</a></span></dt><dt><span class="section"><a href="#what-is-a-branch">Understanding history: What is a branch?</a></span></dt></dl></dd><dt><span class="section"><a href="#manipulating-branches">Manipulating branches</a></span></dt><dt><span class="section"><a href="#detached-head">Examining an old version without creating a new branch</a></span></dt><dt><span class="section"><a href="#examining-remote-branches">Examining branches from a remote repository</a></span></dt><dt><span class="section"><a href="#how-git-stores-references">Naming branches, tags, and other references</a></span></dt><dt><span class="section"><a href="#Updating-a-repository-with-git-fetch">Updating a repository with git-fetch</a></span></dt><dt><span class="section"><a href="#fetching-branches">Fetching branches from other repositories</a></span></dt></dl></dd><dt><span class="chapter"><a href="#exploring-git-history">2. Exploring git history</a></span></dt><dd><dl><dt><span class="section"><a href="#using-bisect">How to use bisect to find a regression</a></span></dt><dt><span class="section"><a href="#naming-commits">Naming commits</a></span></dt><dt><span class="section"><a href="#creating-tags">Creating tags</a></span></dt><dt><span class="section"><a href="#browsing-revisions">Browsing revisions</a></span></dt><dt><span class="section"><a href="#generating-diffs">Generating diffs</a></span></dt><dt><span class="section"><a href="#viewing-old-file-versions">Viewing old file versions</a></span></dt><dt><span class="section"><a href="#history-examples">Examples</a></span></dt><dd><dl><dt><span class="section"><a href="#counting-commits-on-a-branch">Counting the number of commits on a branch</a></span></dt><dt><span class="section"><a href="#checking-for-equal-branches">Check whether two branches point at the same history</a></span></dt><dt><span class="section"><a href="#finding-tagged-descendants">Find first tagged version including a given fix</a></span></dt><dt><span class="section"><a href="#showing-commits-unique-to-a-branch">Showing commits unique to a given branch</a></span></dt><dt><span class="section"><a href="#making-a-release">Creating a changelog and tarball for a software release</a></span></dt><dt><span class="section"><a href="#Finding-comments-with-given-content">Finding commits referencing a file with given content</a></span></dt></dl></dd></dl></dd><dt><span class="chapter"><a href="#Developing-with-git">3. Developing with git</a></span></dt><dd><dl><dt><span class="section"><a href="#telling-git-your-name">Telling git your name</a></span></dt><dt><span class="section"><a href="#creating-a-new-repository">Creating a new repository</a></span></dt><dt><span class="section"><a href="#how-to-make-a-commit">How to make a commit</a></span></dt><dt><span class="section"><a href="#creating-good-commit-messages">Creating good commit messages</a></span></dt><dt><span class="section"><a href="#ignoring-files">Ignoring files</a></span></dt><dt><span class="section"><a href="#how-to-merge">How to merge</a></span></dt><dt><span class="section"><a href="#resolving-a-merge">Resolving a merge</a></span></dt><dd><dl><dt><span class="section"><a href="#conflict-resolution">Getting conflict-resolution help during a merge</a></span></dt></dl></dd><dt><span class="section"><a href="#undoing-a-merge">Undoing a merge</a></span></dt><dt><span class="section"><a href="#fast-forwards">Fast-forward merges</a></span></dt><dt><span class="section"><a href="#fixing-mistakes">Fixing mistakes</a></span></dt><dd><dl><dt><span class="section"><a href="#reverting-a-commit">Fixing a mistake with a new commit</a></span></dt><dt><span class="section"><a href="#fixing-a-mistake-by-rewriting-history">Fixing a mistake by rewriting history</a></span></dt><dt><span class="section"><a href="#checkout-of-path">Checking out an old version of a file</a></span></dt><dt><span class="section"><a href="#interrupted-work">Temporarily setting aside work in progress</a></span></dt></dl></dd><dt><span class="section"><a href="#ensuring-good-performance">Ensuring good performance</a></span></dt><dt><span class="section"><a href="#ensuring-reliability">Ensuring reliability</a></span></dt><dd><dl><dt><span class="section"><a href="#checking-for-corruption">Checking the repository for corruption</a></span></dt><dt><span class="section"><a href="#recovering-lost-changes">Recovering lost changes</a></span></dt></dl></dd></dl></dd><dt><span class="chapter"><a href="#sharing-development">4. Sharing development with others</a></span></dt><dd><dl><dt><span class="section"><a href="#getting-updates-with-git-pull">Getting updates with git-pull</a></span></dt><dt><span class="section"><a href="#submitting-patches">Submitting patches to a project</a></span></dt><dt><span class="section"><a href="#importing-patches">Importing patches to a project</a></span></dt><dt><span class="section"><a href="#public-repositories">Public git repositories</a></span></dt><dd><dl><dt><span class="section"><a href="#setting-up-a-public-repository">Setting up a public repository</a></span></dt><dt><span class="section"><a href="#exporting-via-git">Exporting a git repository via the git protocol</a></span></dt><dt><span class="section"><a href="#exporting-via-http">Exporting a git repository via http</a></span></dt><dt><span class="section"><a href="#pushing-changes-to-a-public-repository">Pushing changes to a public repository</a></span></dt><dt><span class="section"><a href="#forcing-push">What to do when a push fails</a></span></dt><dt><span class="section"><a href="#setting-up-a-shared-repository">Setting up a shared repository</a></span></dt><dt><span class="section"><a href="#setting-up-gitweb">Allowing web browsing of a repository</a></span></dt></dl></dd><dt><span class="section"><a href="#sharing-development-examples">Examples</a></span></dt><dd><dl><dt><span class="section"><a href="#maintaining-topic-branches">Maintaining topic branches for a Linux subsystem maintainer</a></span></dt></dl></dd></dl></dd><dt><span class="chapter"><a href="#cleaning-up-history">5. Rewriting history and maintaining patch series</a></span></dt><dd><dl><dt><span class="section"><a href="#patch-series">Creating the perfect patch series</a></span></dt><dt><span class="section"><a href="#using-git-rebase">Keeping a patch series up to date using git-rebase</a></span></dt><dt><span class="section"><a href="#rewriting-one-commit">Rewriting a single commit</a></span></dt><dt><span class="section"><a href="#reordering-patch-series">Reordering or selecting from a patch series</a></span></dt><dt><span class="section"><a href="#patch-series-tools">Other tools</a></span></dt><dt><span class="section"><a href="#problems-with-rewriting-history">Problems with rewriting history</a></span></dt><dt><span class="section"><a href="#bisect-merges">Why bisecting merge commits can be harder than bisecting linear history</a></span></dt></dl></dd><dt><span class="chapter"><a href="#advanced-branch-management">6. Advanced branch management</a></span></dt><dd><dl><dt><span class="section"><a href="#fetching-individual-branches">Fetching individual branches</a></span></dt><dt><span class="section"><a href="#fetch-fast-forwards">git fetch and fast-forwards</a></span></dt><dt><span class="section"><a href="#forcing-fetch">Forcing git-fetch to do non-fast-forward updates</a></span></dt><dt><span class="section"><a href="#remote-branch-configuration">Configuring remote branches</a></span></dt></dl></dd><dt><span class="chapter"><a href="#git-concepts">7. Git concepts</a></span></dt><dd><dl><dt><span class="section"><a href="#the-object-database">The Object Database</a></span></dt><dd><dl><dt><span class="section"><a href="#commit-object">Commit Object</a></span></dt><dt><span class="section"><a href="#tree-object">Tree Object</a></span></dt><dt><span class="section"><a href="#blob-object">Blob Object</a></span></dt><dt><span class="section"><a href="#trust">Trust</a></span></dt><dt><span class="section"><a href="#tag-object">Tag Object</a></span></dt><dt><span class="section"><a href="#pack-files">How git stores objects efficiently: pack files</a></span></dt><dt><span class="section"><a href="#dangling-objects">Dangling objects</a></span></dt><dt><span class="section"><a href="#recovering-from-repository-corruption">Recovering from repository corruption</a></span></dt></dl></dd><dt><span class="section"><a href="#the-index">The index</a></span></dt></dl></dd><dt><span class="chapter"><a href="#submodules">8. Submodules</a></span></dt><dd><dl><dt><span class="section"><a href="#id280263">Pitfalls with submodules</a></span></dt></dl></dd><dt><span class="chapter"><a href="#low-level-operations">9. Low-level git operations</a></span></dt><dd><dl><dt><span class="section"><a href="#object-manipulation">Object access and manipulation</a></span></dt><dt><span class="section"><a href="#the-workflow">The Workflow</a></span></dt><dd><dl><dt><span class="section"><a href="#working-directory-to-index">working directory -> index</a></span></dt><dt><span class="section"><a href="#index-to-object-database">index -> object database</a></span></dt><dt><span class="section"><a href="#object-database-to-index">object database -> index</a></span></dt><dt><span class="section"><a href="#index-to-working-directory">index -> working directory</a></span></dt><dt><span class="section"><a href="#tying-it-all-together">Tying it all together</a></span></dt></dl></dd><dt><span class="section"><a href="#examining-the-data">Examining the data</a></span></dt><dt><span class="section"><a href="#merging-multiple-trees">Merging multiple trees</a></span></dt><dt><span class="section"><a href="#merging-multiple-trees-2">Merging multiple trees, continued</a></span></dt></dl></dd><dt><span class="chapter"><a href="#hacking-git">10. Hacking git</a></span></dt><dd><dl><dt><span class="section"><a href="#object-details">Object storage format</a></span></dt><dt><span class="section"><a href="#birdview-on-the-source-code">A birds-eye view of Git's source code</a></span></dt></dl></dd><dt><span class="chapter"><a href="#glossary">11. GIT Glossary</a></span></dt><dt><span class="appendix"><a href="#git-quick-start">A. Git Quick Reference</a></span></dt><dd><dl><dt><span class="section"><a href="#quick-creating-a-new-repository">Creating a new repository</a></span></dt><dt><span class="section"><a href="#managing-branches">Managing branches</a></span></dt><dt><span class="section"><a href="#exploring-history">Exploring history</a></span></dt><dt><span class="section"><a href="#making-changes">Making changes</a></span></dt><dt><span class="section"><a href="#merging">Merging</a></span></dt><dt><span class="section"><a href="#sharing-your-changes">Sharing your changes</a></span></dt><dt><span class="section"><a href="#repository-maintenance">Repository maintenance</a></span></dt></dl></dd><dt><span class="appendix"><a href="#todo">B. Notes and todo list for this manual</a></span></dt></dl></div><div class="preface" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id264725"></a>Preface</h2></div></div></div><p>Git is a fast distributed revision control system.</p><p>This manual is designed to be readable by someone with basic UNIX |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 2 | command-line skills, but no previous knowledge of git.</p><p><a href="#repositories-and-branches" title="Chapter 1. Repositories and Branches">Chapter 1, <i>Repositories and Branches</i></a> and <a href="#exploring-git-history" title="Chapter 2. Exploring git history">Chapter 2, <i>Exploring git history</i></a> explain how |
| 3 | to fetch and study a project using git—read these chapters to learn how |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 4 | to build and test a particular version of a software project, search for |
| 5 | regressions, and so on.</p><p>People needing to do actual development will also want to read |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 6 | <a href="#Developing-with-git" title="Chapter 3. Developing with git">Chapter 3, <i>Developing with git</i></a> and <a href="#sharing-development" title="Chapter 4. Sharing development with others">Chapter 4, <i>Sharing development with others</i></a>.</p><p>Further chapters cover more specialized topics.</p><p>Comprehensive reference documentation is available through the man |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 7 | pages. For a command such as "git clone <repo>", just use</p><div class="literallayout"><p>$ man git-clone</p></div><p>See also <a href="#git-quick-start" title="Appendix A. Git Quick Reference">Appendix A, <i>Git Quick Reference</i></a> for a brief overview of git commands, |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 8 | without any explanation.</p><p>Finally, see <a href="#todo" title="Appendix B. Notes and todo list for this manual">Appendix B, <i>Notes and todo list for this manual</i></a> for ways that you can help make this manual more |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 9 | complete.</p></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="repositories-and-branches"></a>Chapter 1. Repositories and Branches</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="section"><a href="#how-to-get-a-git-repository">How to get a git repository</a></span></dt><dt><span class="section"><a href="#how-to-check-out">How to check out a different version of a project</a></span></dt><dt><span class="section"><a href="#understanding-commits">Understanding History: Commits</a></span></dt><dd><dl><dt><span class="section"><a href="#understanding-reachability">Understanding history: commits, parents, and reachability</a></span></dt><dt><span class="section"><a href="#history-diagrams">Understanding history: History diagrams</a></span></dt><dt><span class="section"><a href="#what-is-a-branch">Understanding history: What is a branch?</a></span></dt></dl></dd><dt><span class="section"><a href="#manipulating-branches">Manipulating branches</a></span></dt><dt><span class="section"><a href="#detached-head">Examining an old version without creating a new branch</a></span></dt><dt><span class="section"><a href="#examining-remote-branches">Examining branches from a remote repository</a></span></dt><dt><span class="section"><a href="#how-git-stores-references">Naming branches, tags, and other references</a></span></dt><dt><span class="section"><a href="#Updating-a-repository-with-git-fetch">Updating a repository with git-fetch</a></span></dt><dt><span class="section"><a href="#fetching-branches">Fetching branches from other repositories</a></span></dt></dl></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="how-to-get-a-git-repository"></a>How to get a git repository</h2></div></div></div><p>It will be useful to have a git repository to experiment with as you |
| Junio C Hamano | 8b8b0f2 | 2007-08-26 22:10:26 | [diff] [blame] | 10 | read this manual.</p><p>The best way to get one is by using the <a href="git-clone.html" target="_top">git-clone(1)</a> command to |
| 11 | download a copy of an existing repository. If you don't already have a |
| 12 | project in mind, here are some interesting examples:</p><div class="literallayout"><p> # git itself (approx. 10MB download):<br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 13 | $ git clone git://git.kernel.org/pub/scm/git/git.git<br> |
| 14 | # the linux kernel (approx. 150MB download):<br> |
| 15 | $ git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git</p></div><p>The initial clone may be time-consuming for a large project, but you |
| Junio C Hamano | ce3650e | 2007-11-26 04:20:11 | [diff] [blame] | 16 | will only need to clone once.</p><p>The clone command creates a new directory named after the project ("git" |
| 17 | or "linux-2.6" in the examples above). After you cd into this |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 18 | directory, you will see that it contains a copy of the project files, |
| Junio C Hamano | ce3650e | 2007-11-26 04:20:11 | [diff] [blame] | 19 | called the <a href="#def_working_tree">working tree</a>, together with a special |
| 20 | top-level directory named ".git", which contains all the information |
| 21 | about the history of the project.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="how-to-check-out"></a>How to check out a different version of a project</h2></div></div></div><p>Git is best thought of as a tool for storing the history of a collection |
| Junio C Hamano | 8b8b0f2 | 2007-08-26 22:10:26 | [diff] [blame] | 22 | of files. It stores the history as a compressed collection of |
| 23 | interrelated snapshots of the project's contents. In git each such |
| Junio C Hamano | ce3650e | 2007-11-26 04:20:11 | [diff] [blame] | 24 | version is called a <a href="#def_commit">commit</a>.</p><p>Those snapshots aren't necessarily all arranged in a single line from |
| 25 | oldest to newest; instead, work may simultaneously proceed along |
| Junio C Hamano | 618bdde | 2008-01-02 10:51:08 | [diff] [blame] | 26 | parallel lines of development, called <a href="#def_branch">branches</a>, which may |
| Junio C Hamano | ce3650e | 2007-11-26 04:20:11 | [diff] [blame] | 27 | merge and diverge.</p><p>A single git repository can track development on multiple branches. It |
| 28 | does this by keeping a list of <a href="#def_head">heads</a> which reference the |
| Junio C Hamano | 8b8b0f2 | 2007-08-26 22:10:26 | [diff] [blame] | 29 | latest commit on each branch; the <a href="git-branch.html" target="_top">git-branch(1)</a> command shows |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 30 | you the list of branch heads:</p><div class="literallayout"><p>$ git branch<br> |
| 31 | * master</p></div><p>A freshly cloned repository contains a single branch head, by default |
| Junio C Hamano | 0e3cb53 | 2007-04-17 08:28:11 | [diff] [blame] | 32 | named "master", with the working directory initialized to the state of |
| 33 | the project referred to by that branch head.</p><p>Most projects also use <a href="#def_tag">tags</a>. Tags, like heads, are |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 34 | references into the project's history, and can be listed using the |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 35 | <a href="git-tag.html" target="_top">git-tag(1)</a> command:</p><div class="literallayout"><p>$ git tag -l<br> |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 36 | v2.6.11<br> |
| 37 | v2.6.11-tree<br> |
| 38 | v2.6.12<br> |
| 39 | v2.6.12-rc2<br> |
| 40 | v2.6.12-rc3<br> |
| 41 | v2.6.12-rc4<br> |
| 42 | v2.6.12-rc5<br> |
| 43 | v2.6.12-rc6<br> |
| 44 | v2.6.13<br> |
| 45 | ...</p></div><p>Tags are expected to always point at the same version of a project, |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 46 | while heads are expected to advance as development progresses.</p><p>Create a new branch head pointing to one of these versions and check it |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 47 | out using <a href="git-checkout.html" target="_top">git-checkout(1)</a>:</p><div class="literallayout"><p>$ git checkout -b new v2.6.13</p></div><p>The working directory then reflects the contents that the project had |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 48 | when it was tagged v2.6.13, and <a href="git-branch.html" target="_top">git-branch(1)</a> shows two |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 49 | branches, with an asterisk marking the currently checked-out branch:</p><div class="literallayout"><p>$ git branch<br> |
| 50 | master<br> |
| 51 | * new</p></div><p>If you decide that you'd rather see version 2.6.17, you can modify |
| 52 | the current branch to point at v2.6.17 instead, with</p><div class="literallayout"><p>$ git reset --hard v2.6.17</p></div><p>Note that if the current branch head was your only reference to a |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 53 | particular point in history, then resetting that branch may leave you |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 54 | with no way to find the history it used to point to; so use this command |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 55 | carefully.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="understanding-commits"></a>Understanding History: Commits</h2></div></div></div><p>Every change in the history of a project is represented by a commit. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 56 | The <a href="git-show.html" target="_top">git-show(1)</a> command shows the most recent commit on the |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 57 | current branch:</p><div class="literallayout"><p>$ git show<br> |
| Junio C Hamano | 8b8b0f2 | 2007-08-26 22:10:26 | [diff] [blame] | 58 | commit 17cf781661e6d38f737f15f53ab552f1e95960d7<br> |
| 59 | Author: Linus Torvalds <torvalds@ppc970.osdl.org.(none)><br> |
| 60 | Date: Tue Apr 19 14:11:06 2005 -0700<br> |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 61 | <br> |
| Junio C Hamano | 8b8b0f2 | 2007-08-26 22:10:26 | [diff] [blame] | 62 | Remove duplicate getenv(DB_ENVIRONMENT) call<br> |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 63 | <br> |
| Junio C Hamano | 8b8b0f2 | 2007-08-26 22:10:26 | [diff] [blame] | 64 | Noted by Tony Luck.<br> |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 65 | <br> |
| Junio C Hamano | 8b8b0f2 | 2007-08-26 22:10:26 | [diff] [blame] | 66 | diff --git a/init-db.c b/init-db.c<br> |
| 67 | index 65898fa..b002dc6 100644<br> |
| 68 | --- a/init-db.c<br> |
| 69 | +++ b/init-db.c<br> |
| 70 | @@ -7,7 +7,7 @@<br> |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 71 | <br> |
| Junio C Hamano | 8b8b0f2 | 2007-08-26 22:10:26 | [diff] [blame] | 72 | int main(int argc, char **argv)<br> |
| 73 | {<br> |
| 74 | - char *sha1_dir = getenv(DB_ENVIRONMENT), *path;<br> |
| 75 | + char *sha1_dir, *path;<br> |
| 76 | int len, i;<br> |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 77 | <br> |
| Junio C Hamano | 8b8b0f2 | 2007-08-26 22:10:26 | [diff] [blame] | 78 | if (mkdir(".git", 0755) < 0) {</p></div><p>As you can see, a commit shows who made the latest change, what they |
| Junio C Hamano | aa83a7d | 2007-03-05 02:37:29 | [diff] [blame] | 79 | did, and why.</p><p>Every commit has a 40-hexdigit id, sometimes called the "object name" or the |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 80 | "SHA1 id", shown on the first line of the "git-show" output. You can usually |
| Junio C Hamano | aa83a7d | 2007-03-05 02:37:29 | [diff] [blame] | 81 | refer to a commit by a shorter name, such as a tag or a branch name, but this |
| 82 | longer name can also be useful. Most importantly, it is a globally unique |
| 83 | name for this commit: so if you tell somebody else the object name (for |
| 84 | example in email), then you are guaranteed that name will refer to the same |
| 85 | commit in their repository that it does in yours (assuming their repository |
| 86 | has that commit at all). Since the object name is computed as a hash over the |
| 87 | contents of the commit, you are guaranteed that the commit can never change |
| Junio C Hamano | 597ffcf | 2007-09-17 17:33:15 | [diff] [blame] | 88 | without its name also changing.</p><p>In fact, in <a href="#git-concepts" title="Chapter 7. Git concepts">Chapter 7, <i>Git concepts</i></a> we shall see that everything stored in git |
| Junio C Hamano | aa83a7d | 2007-03-05 02:37:29 | [diff] [blame] | 89 | history, including file data and directory contents, is stored in an object |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 90 | with a name that is a hash of its contents.</p><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="understanding-reachability"></a>Understanding history: commits, parents, and reachability</h3></div></div></div><p>Every commit (except the very first commit in a project) also has a |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 91 | parent commit which shows what happened before this commit. |
| 92 | Following the chain of parents will eventually take you back to the |
| 93 | beginning of the project.</p><p>However, the commits do not form a simple list; git allows lines of |
| 94 | development to diverge and then reconverge, and the point where two |
| 95 | lines of development reconverge is called a "merge". The commit |
| 96 | representing a merge can therefore have more than one parent, with |
| 97 | each parent representing the most recent commit on one of the lines |
| 98 | of development leading to that point.</p><p>The best way to see how this works is using the <a href="gitk.html" target="_top">gitk(1)</a> |
| 99 | command; running gitk now on a git repository and looking for merge |
| 100 | commits will help understand how the git organizes history.</p><p>In the following, we say that commit X is "reachable" from commit Y |
| 101 | if commit X is an ancestor of commit Y. Equivalently, you could say |
| Junio C Hamano | a638742 | 2007-08-25 03:54:27 | [diff] [blame] | 102 | that Y is a descendant of X, or that there is a chain of parents |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 103 | leading from commit Y to commit X.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="history-diagrams"></a>Understanding history: History diagrams</h3></div></div></div><p>We will sometimes represent git history using diagrams like the one |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 104 | below. Commits are shown as "o", and the links between them with |
| Junio C Hamano | c51fede | 2007-03-12 07:29:20 | [diff] [blame] | 105 | lines drawn with - / and \. Time goes left to right:</p><pre class="literallayout"> o--o--o <-- Branch A |
| 106 | / |
| 107 | o--o--o <-- master |
| 108 | \ |
| 109 | o--o--o <-- Branch B</pre><p>If we need to talk about a particular commit, the character "o" may |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 110 | be replaced with another letter or number.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="what-is-a-branch"></a>Understanding history: What is a branch?</h3></div></div></div><p>When we need to be precise, we will use the word "branch" to mean a line |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 111 | of development, and "branch head" (or just "head") to mean a reference |
| 112 | to the most recent commit on a branch. In the example above, the branch |
| 113 | head named "A" is a pointer to one particular commit, but we refer to |
| 114 | the line of three commits leading up to that point as all being part of |
| 115 | "branch A".</p><p>However, when no confusion will result, we often just use the term |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 116 | "branch" both for branches and for branch heads.</p></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="manipulating-branches"></a>Manipulating branches</h2></div></div></div><p>Creating, deleting, and modifying branches is quick and easy; here's |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 117 | a summary of the commands:</p><div class="variablelist"><dl><dt><span class="term"> |
| 118 | git branch |
| 119 | </span></dt><dd> |
| 120 | list all branches |
| 121 | </dd><dt><span class="term"> |
| 122 | git branch <branch> |
| 123 | </span></dt><dd> |
| 124 | create a new branch named <branch>, referencing the same |
| 125 | point in history as the current branch |
| 126 | </dd><dt><span class="term"> |
| 127 | git branch <branch> <start-point> |
| 128 | </span></dt><dd> |
| 129 | create a new branch named <branch>, referencing |
| 130 | <start-point>, which may be specified any way you like, |
| 131 | including using a branch name or a tag name |
| 132 | </dd><dt><span class="term"> |
| 133 | git branch -d <branch> |
| 134 | </span></dt><dd> |
| 135 | delete the branch <branch>; if the branch you are deleting |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 136 | points to a commit which is not reachable from the current |
| 137 | branch, this command will fail with a warning. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 138 | </dd><dt><span class="term"> |
| 139 | git branch -D <branch> |
| 140 | </span></dt><dd> |
| 141 | even if the branch points to a commit not reachable |
| 142 | from the current branch, you may know that that commit |
| 143 | is still reachable from some other branch or tag. In that |
| 144 | case it is safe to use this command to force git to delete |
| 145 | the branch. |
| 146 | </dd><dt><span class="term"> |
| 147 | git checkout <branch> |
| 148 | </span></dt><dd> |
| 149 | make the current branch <branch>, updating the working |
| 150 | directory to reflect the version referenced by <branch> |
| 151 | </dd><dt><span class="term"> |
| 152 | git checkout -b <new> <start-point> |
| 153 | </span></dt><dd> |
| 154 | create a new branch <new> referencing <start-point>, and |
| 155 | check it out. |
| Junio C Hamano | 0e3cb53 | 2007-04-17 08:28:11 | [diff] [blame] | 156 | </dd></dl></div><p>The special symbol "HEAD" can always be used to refer to the current |
| 157 | branch. In fact, git uses a file named "HEAD" in the .git directory to |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 158 | remember which branch is current:</p><div class="literallayout"><p>$ cat .git/HEAD<br> |
| 159 | ref: refs/heads/master</p></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="detached-head"></a>Examining an old version without creating a new branch</h2></div></div></div><p>The git-checkout command normally expects a branch head, but will also |
| Junio C Hamano | 0e3cb53 | 2007-04-17 08:28:11 | [diff] [blame] | 160 | accept an arbitrary commit; for example, you can check out the commit |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 161 | referenced by a tag:</p><div class="literallayout"><p>$ git checkout v2.6.17<br> |
| 162 | Note: moving to "v2.6.17" which isn't a local branch<br> |
| 163 | If you want to create a new branch from this checkout, you may do so<br> |
| 164 | (now or later) by using -b with the checkout command again. Example:<br> |
| 165 | git checkout -b <new_branch_name><br> |
| 166 | HEAD is now at 427abfa... Linux v2.6.17</p></div><p>The HEAD then refers to the SHA1 of the commit instead of to a branch, |
| 167 | and git branch shows that you are no longer on a branch:</p><div class="literallayout"><p>$ cat .git/HEAD<br> |
| Junio C Hamano | 0e3cb53 | 2007-04-17 08:28:11 | [diff] [blame] | 168 | 427abfa28afedffadfca9dd8b067eb6d36bac53f<br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 169 | $ git branch<br> |
| 170 | * (no branch)<br> |
| 171 | master</p></div><p>In this case we say that the HEAD is "detached".</p><p>This is an easy way to check out a particular version without having to |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 172 | make up a name for the new branch. You can still create a new branch |
| 173 | (or tag) for this version later if you decide to.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="examining-remote-branches"></a>Examining branches from a remote repository</h2></div></div></div><p>The "master" branch that was created at the time you cloned is a copy |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 174 | of the HEAD in the repository that you cloned from. That repository |
| 175 | may also have had other branches, though, and your local repository |
| 176 | keeps branches which track each of those remote branches, which you |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 177 | can view using the "-r" option to <a href="git-branch.html" target="_top">git-branch(1)</a>:</p><div class="literallayout"><p>$ git branch -r<br> |
| 178 | origin/HEAD<br> |
| 179 | origin/html<br> |
| 180 | origin/maint<br> |
| 181 | origin/man<br> |
| 182 | origin/master<br> |
| 183 | origin/next<br> |
| 184 | origin/pu<br> |
| 185 | origin/todo</p></div><p>You cannot check out these remote-tracking branches, but you can |
| 186 | examine them on a branch of your own, just as you would a tag:</p><div class="literallayout"><p>$ git checkout -b my-todo-copy origin/todo</p></div><p>Note that the name "origin" is just the name that git uses by default |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 187 | to refer to the repository that you cloned from.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="how-git-stores-references"></a>Naming branches, tags, and other references</h2></div></div></div><p>Branches, remote-tracking branches, and tags are all references to |
| 188 | commits. All references are named with a slash-separated path name |
| 189 | starting with "refs"; the names we've been using so far are actually |
| 190 | shorthand:</p><div class="itemizedlist"><ul type="disc"><li> |
| 191 | The branch "test" is short for "refs/heads/test". |
| 192 | </li><li> |
| 193 | The tag "v2.6.18" is short for "refs/tags/v2.6.18". |
| 194 | </li><li> |
| 195 | "origin/master" is short for "refs/remotes/origin/master". |
| 196 | </li></ul></div><p>The full name is occasionally useful if, for example, there ever |
| Junio C Hamano | 9810d63 | 2007-09-24 01:05:34 | [diff] [blame] | 197 | exists a tag and a branch with the same name.</p><p>(Newly created refs are actually stored in the .git/refs directory, |
| 198 | under the path given by their name. However, for efficiency reasons |
| 199 | they may also be packed together in a single file; see |
| 200 | <a href="git-pack-refs.html" target="_top">git-pack-refs(1)</a>).</p><p>As another useful shortcut, the "HEAD" of a repository can be referred |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 201 | to just using the name of that repository. So, for example, "origin" |
| 202 | is usually a shortcut for the HEAD branch in the repository "origin".</p><p>For the complete list of paths which git checks for references, and |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 203 | the order it uses to decide which to choose when there are multiple |
| 204 | references with the same shorthand name, see the "SPECIFYING |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 205 | REVISIONS" section of <a href="git-rev-parse.html" target="_top">git-rev-parse(1)</a>.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="Updating-a-repository-with-git-fetch"></a>Updating a repository with git-fetch</h2></div></div></div><p>Eventually the developer cloned from will do additional work in her |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 206 | repository, creating new commits and advancing the branches to point |
| 207 | at the new commits.</p><p>The command "git fetch", with no arguments, will update all of the |
| 208 | remote-tracking branches to the latest version found in her |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 209 | repository. It will not touch any of your own branches—not even the |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 210 | "master" branch that was created for you on clone.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="fetching-branches"></a>Fetching branches from other repositories</h2></div></div></div><p>You can also track branches from repositories other than the one you |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 211 | cloned from, using <a href="git-remote.html" target="_top">git-remote(1)</a>:</p><div class="literallayout"><p>$ git remote add linux-nfs git://linux-nfs.org/pub/nfs-2.6.git<br> |
| 212 | $ git fetch linux-nfs<br> |
| 213 | * refs/remotes/linux-nfs/master: storing branch 'master' ...<br> |
| 214 | commit: bf81b46</p></div><p>New remote-tracking branches will be stored under the shorthand name |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 215 | that you gave "git-remote add", in this case linux-nfs:</p><div class="literallayout"><p>$ git branch -r<br> |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 216 | linux-nfs/master<br> |
| 217 | origin/master</p></div><p>If you run "git fetch <remote>" later, the tracking branches for the |
| 218 | named <remote> will be updated.</p><p>If you examine the file .git/config, you will see that git has added |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 219 | a new stanza:</p><div class="literallayout"><p>$ cat .git/config<br> |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 220 | ...<br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 221 | [remote "linux-nfs"]<br> |
| 222 | url = git://linux-nfs.org/pub/nfs-2.6.git<br> |
| 223 | fetch = +refs/heads/*:refs/remotes/linux-nfs/*<br> |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 224 | ...</p></div><p>This is what causes git to track the remote's branches; you may modify |
| 225 | or delete these configuration options by editing .git/config with a |
| 226 | text editor. (See the "CONFIGURATION FILE" section of |
| Junio C Hamano | 8b8b0f2 | 2007-08-26 22:10:26 | [diff] [blame] | 227 | <a href="git-config.html" target="_top">git-config(1)</a> for details.)</p></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="exploring-git-history"></a>Chapter 2. Exploring git history</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="section"><a href="#using-bisect">How to use bisect to find a regression</a></span></dt><dt><span class="section"><a href="#naming-commits">Naming commits</a></span></dt><dt><span class="section"><a href="#creating-tags">Creating tags</a></span></dt><dt><span class="section"><a href="#browsing-revisions">Browsing revisions</a></span></dt><dt><span class="section"><a href="#generating-diffs">Generating diffs</a></span></dt><dt><span class="section"><a href="#viewing-old-file-versions">Viewing old file versions</a></span></dt><dt><span class="section"><a href="#history-examples">Examples</a></span></dt><dd><dl><dt><span class="section"><a href="#counting-commits-on-a-branch">Counting the number of commits on a branch</a></span></dt><dt><span class="section"><a href="#checking-for-equal-branches">Check whether two branches point at the same history</a></span></dt><dt><span class="section"><a href="#finding-tagged-descendants">Find first tagged version including a given fix</a></span></dt><dt><span class="section"><a href="#showing-commits-unique-to-a-branch">Showing commits unique to a given branch</a></span></dt><dt><span class="section"><a href="#making-a-release">Creating a changelog and tarball for a software release</a></span></dt><dt><span class="section"><a href="#Finding-comments-with-given-content">Finding commits referencing a file with given content</a></span></dt></dl></dd></dl></div><p>Git is best thought of as a tool for storing the history of a |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 228 | collection of files. It does this by storing compressed snapshots of |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 229 | the contents of a file hierarchy, together with "commits" which show |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 230 | the relationships between these snapshots.</p><p>Git provides extremely flexible and fast tools for exploring the |
| Junio C Hamano | 39381a7 | 2007-02-02 07:35:15 | [diff] [blame] | 231 | history of a project.</p><p>We start with one specialized tool that is useful for finding the |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 232 | commit that introduced a bug into a project.</p><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="using-bisect"></a>How to use bisect to find a regression</h2></div></div></div><p>Suppose version 2.6.18 of your project worked, but the version at |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 233 | "master" crashes. Sometimes the best way to find the cause of such a |
| 234 | regression is to perform a brute-force search through the project's |
| 235 | history to find the particular commit that caused the problem. The |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 236 | <a href="git-bisect.html" target="_top">git-bisect(1)</a> command can help you do this:</p><div class="literallayout"><p>$ git bisect start<br> |
| 237 | $ git bisect good v2.6.18<br> |
| 238 | $ git bisect bad master<br> |
| 239 | Bisecting: 3537 revisions left to test after this<br> |
| 240 | [65934a9a028b88e83e2b0f8b36618fe503349f8e] BLOCK: Make USB storage depend on SCSI rather than selecting it [try #6]</p></div><p>If you run "git branch" at this point, you'll see that git has |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 241 | temporarily moved you to a new branch named "bisect". This branch |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 242 | points to a commit (with commit id 65934…) that is reachable from |
| Junio C Hamano | 361c133 | 2007-11-14 12:17:22 | [diff] [blame] | 243 | "master" but not from v2.6.18. Compile and test it, and see whether |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 244 | it crashes. Assume it does crash. Then:</p><div class="literallayout"><p>$ git bisect bad<br> |
| 245 | Bisecting: 1769 revisions left to test after this<br> |
| 246 | [7eff82c8b1511017ae605f0c99ac275a7e21b867] i2c-core: Drop useless bitmaskings</p></div><p>checks out an older version. Continue like this, telling git at each |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 247 | stage whether the version it gives you is good or bad, and notice |
| 248 | that the number of revisions left to test is cut approximately in |
| 249 | half each time.</p><p>After about 13 tests (in this case), it will output the commit id of |
| 250 | the guilty commit. You can then examine the commit with |
| 251 | <a href="git-show.html" target="_top">git-show(1)</a>, find out who wrote it, and mail them your bug |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 252 | report with the commit id. Finally, run</p><div class="literallayout"><p>$ git bisect reset</p></div><p>to return you to the branch you were on before and delete the |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 253 | temporary "bisect" branch.</p><p>Note that the version which git-bisect checks out for you at each |
| 254 | point is just a suggestion, and you're free to try a different |
| 255 | version if you think it would be a good idea. For example, |
| 256 | occasionally you may land on a commit that broke something unrelated; |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 257 | run</p><div class="literallayout"><p>$ git bisect visualize</p></div><p>which will run gitk and label the commit it chose with a marker that |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 258 | says "bisect". Chose a safe-looking commit nearby, note its commit |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 259 | id, and check it out with:</p><div class="literallayout"><p>$ git reset --hard fb47ddb2db...</p></div><p>then test, run "bisect good" or "bisect bad" as appropriate, and |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 260 | continue.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="naming-commits"></a>Naming commits</h2></div></div></div><p>We have seen several ways of naming commits already:</p><div class="itemizedlist"><ul type="disc"><li> |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 261 | 40-hexdigit object name |
| 262 | </li><li> |
| 263 | branch name: refers to the commit at the head of the given |
| 264 | branch |
| 265 | </li><li> |
| 266 | tag name: refers to the commit pointed to by the given tag |
| 267 | (we've seen branches and tags are special cases of |
| 268 | <a href="#how-git-stores-references" title="Naming branches, tags, and other references">references</a>). |
| 269 | </li><li> |
| 270 | HEAD: refers to the head of the current branch |
| 271 | </li></ul></div><p>There are many more; see the "SPECIFYING REVISIONS" section of the |
| 272 | <a href="git-rev-parse.html" target="_top">git-rev-parse(1)</a> man page for the complete list of ways to |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 273 | name revisions. Some examples:</p><div class="literallayout"><p>$ git show fb47ddb2 # the first few characters of the object name<br> |
| 274 | # are usually enough to specify it uniquely<br> |
| 275 | $ git show HEAD^ # the parent of the HEAD commit<br> |
| 276 | $ git show HEAD^^ # the grandparent<br> |
| 277 | $ git show HEAD~4 # the great-great-grandparent</p></div><p>Recall that merge commits may have more than one parent; by default, |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 278 | ^ and ~ follow the first parent listed in the commit, but you can |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 279 | also choose:</p><div class="literallayout"><p>$ git show HEAD^1 # show the first parent of HEAD<br> |
| 280 | $ git show HEAD^2 # show the second parent of HEAD</p></div><p>In addition to HEAD, there are several other special names for |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 281 | commits:</p><p>Merges (to be discussed later), as well as operations such as |
| 282 | git-reset, which change the currently checked-out commit, generally |
| 283 | set ORIG_HEAD to the value HEAD had before the current operation.</p><p>The git-fetch operation always stores the head of the last fetched |
| 284 | branch in FETCH_HEAD. For example, if you run git fetch without |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 285 | specifying a local branch as the target of the operation</p><div class="literallayout"><p>$ git fetch git://example.com/proj.git theirbranch</p></div><p>the fetched commits will still be available from FETCH_HEAD.</p><p>When we discuss merges we'll also see the special name MERGE_HEAD, |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 286 | which refers to the other branch that we're merging in to the current |
| 287 | branch.</p><p>The <a href="git-rev-parse.html" target="_top">git-rev-parse(1)</a> command is a low-level command that is |
| 288 | occasionally useful for translating some name for a commit to the object |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 289 | name for that commit:</p><div class="literallayout"><p>$ git rev-parse origin<br> |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 290 | e05db0fd4f31dde7005f075a84f96b360d05984b</p></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="creating-tags"></a>Creating tags</h2></div></div></div><p>We can also create a tag to refer to a particular commit; after |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 291 | running</p><div class="literallayout"><p>$ git tag stable-1 1b2e1d63ff</p></div><p>You can use stable-1 to refer to the commit 1b2e1d63ff.</p><p>This creates a "lightweight" tag. If you would also like to include a |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 292 | comment with the tag, and possibly sign it cryptographically, then you |
| 293 | should create a tag object instead; see the <a href="git-tag.html" target="_top">git-tag(1)</a> man page |
| 294 | for details.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="browsing-revisions"></a>Browsing revisions</h2></div></div></div><p>The <a href="git-log.html" target="_top">git-log(1)</a> command can show lists of commits. On its |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 295 | own, it shows all commits reachable from the parent commit; but you |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 296 | can also make more specific requests:</p><div class="literallayout"><p>$ git log v2.5.. # commits since (not reachable from) v2.5<br> |
| 297 | $ git log test..master # commits reachable from master but not test<br> |
| 298 | $ git log master..test # ...reachable from test but not master<br> |
| 299 | $ git log master...test # ...reachable from either test or master,<br> |
| 300 | # but not both<br> |
| 301 | $ git log --since="2 weeks ago" # commits from the last 2 weeks<br> |
| 302 | $ git log Makefile # commits which modify Makefile<br> |
| 303 | $ git log fs/ # ... which modify any file under fs/<br> |
| 304 | $ git log -S'foo()' # commits which add or remove any file data<br> |
| 305 | # matching the string 'foo()'</p></div><p>And of course you can combine all of these; the following finds |
| 306 | commits since v2.5 which touch the Makefile or any file under fs:</p><div class="literallayout"><p>$ git log v2.5.. Makefile fs/</p></div><p>You can also ask git log to show patches:</p><div class="literallayout"><p>$ git log -p</p></div><p>See the "—pretty" option in the <a href="git-log.html" target="_top">git-log(1)</a> man page for more |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 307 | display options.</p><p>Note that git log starts with the most recent commit and works |
| 308 | backwards through the parents; however, since git history can contain |
| Junio C Hamano | ee1e428 | 2007-02-04 08:32:04 | [diff] [blame] | 309 | multiple independent lines of development, the particular order that |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 310 | commits are listed in may be somewhat arbitrary.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="generating-diffs"></a>Generating diffs</h2></div></div></div><p>You can generate diffs between any two versions using |
| Junio C Hamano | 393e57f | 2007-11-20 04:53:25 | [diff] [blame] | 311 | <a href="git-diff.html" target="_top">git-diff(1)</a>:</p><div class="literallayout"><p>$ git diff master..test</p></div><p>That will produce the diff between the tips of the two branches. If |
| 312 | you'd prefer to find the diff from their common ancestor to test, you |
| 313 | can use three dots instead of two:</p><div class="literallayout"><p>$ git diff master...test</p></div><p>Sometimes what you want instead is a set of patches; for this you can |
| 314 | use <a href="git-format-patch.html" target="_top">git-format-patch(1)</a>:</p><div class="literallayout"><p>$ git format-patch master..test</p></div><p>will generate a file with a patch for each commit reachable from test |
| 315 | but not from master.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="viewing-old-file-versions"></a>Viewing old file versions</h2></div></div></div><p>You can always view an old version of a file by just checking out the |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 316 | correct revision first. But sometimes it is more convenient to be |
| 317 | able to view an old version of a single file without checking |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 318 | anything out; this command does that:</p><div class="literallayout"><p>$ git show v2.5:fs/locks.c</p></div><p>Before the colon may be anything that names a commit, and after it |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 319 | may be any path to a file tracked by git.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="history-examples"></a>Examples</h2></div></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="counting-commits-on-a-branch"></a>Counting the number of commits on a branch</h3></div></div></div><p>Suppose you want to know how many commits you've made on "mybranch" |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 320 | since it diverged from "origin":</p><div class="literallayout"><p>$ git log --pretty=oneline origin..mybranch | wc -l</p></div><p>Alternatively, you may often see this sort of thing done with the |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 321 | lower-level command <a href="git-rev-list.html" target="_top">git-rev-list(1)</a>, which just lists the SHA1's |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 322 | of all the given commits:</p><div class="literallayout"><p>$ git rev-list origin..mybranch | wc -l</p></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="checking-for-equal-branches"></a>Check whether two branches point at the same history</h3></div></div></div><p>Suppose you want to check whether two branches point at the same point |
| 323 | in history.</p><div class="literallayout"><p>$ git diff origin..master</p></div><p>will tell you whether the contents of the project are the same at the |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 324 | two branches; in theory, however, it's possible that the same project |
| 325 | contents could have been arrived at by two different historical |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 326 | routes. You could compare the object names:</p><div class="literallayout"><p>$ git rev-list origin<br> |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 327 | e05db0fd4f31dde7005f075a84f96b360d05984b<br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 328 | $ git rev-list master<br> |
| 329 | e05db0fd4f31dde7005f075a84f96b360d05984b</p></div><p>Or you could recall that the … operator selects all commits |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 330 | contained reachable from either one reference or the other but not |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 331 | both: so</p><div class="literallayout"><p>$ git log origin...master</p></div><p>will return no commits when the two branches are equal.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="finding-tagged-descendants"></a>Find first tagged version including a given fix</h3></div></div></div><p>Suppose you know that the commit e05db0fd fixed a certain problem. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 332 | You'd like to find the earliest tagged release that contains that |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 333 | fix.</p><p>Of course, there may be more than one answer—if the history branched |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 334 | after commit e05db0fd, then there could be multiple "earliest" tagged |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 335 | releases.</p><p>You could just visually inspect the commits since e05db0fd:</p><div class="literallayout"><p>$ gitk e05db0fd..</p></div><p>Or you can use <a href="git-name-rev.html" target="_top">git-name-rev(1)</a>, which will give the commit a |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 336 | name based on any tag it finds pointing to one of the commit's |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 337 | descendants:</p><div class="literallayout"><p>$ git name-rev --tags e05db0fd<br> |
| 338 | e05db0fd tags/v1.5.0-rc1^0~23</p></div><p>The <a href="git-describe.html" target="_top">git-describe(1)</a> command does the opposite, naming the |
| 339 | revision using a tag on which the given commit is based:</p><div class="literallayout"><p>$ git describe e05db0fd<br> |
| Junio C Hamano | 4c6aa8a | 2007-04-04 08:56:37 | [diff] [blame] | 340 | v1.5.0-rc0-260-ge05db0f</p></div><p>but that may sometimes help you guess which tags might come after the |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 341 | given commit.</p><p>If you just want to verify whether a given tagged version contains a |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 342 | given commit, you could use <a href="git-merge-base.html" target="_top">git-merge-base(1)</a>:</p><div class="literallayout"><p>$ git merge-base e05db0fd v1.5.0-rc1<br> |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 343 | e05db0fd4f31dde7005f075a84f96b360d05984b</p></div><p>The merge-base command finds a common ancestor of the given commits, |
| 344 | and always returns one or the other in the case where one is a |
| 345 | descendant of the other; so the above output shows that e05db0fd |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 346 | actually is an ancestor of v1.5.0-rc1.</p><p>Alternatively, note that</p><div class="literallayout"><p>$ git log v1.5.0-rc1..e05db0fd</p></div><p>will produce empty output if and only if v1.5.0-rc1 includes e05db0fd, |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 347 | because it outputs only commits that are not reachable from v1.5.0-rc1.</p><p>As yet another alternative, the <a href="git-show-branch.html" target="_top">git-show-branch(1)</a> command lists |
| 348 | the commits reachable from its arguments with a display on the left-hand |
| 349 | side that indicates which arguments that commit is reachable from. So, |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 350 | you can run something like</p><div class="literallayout"><p>$ git show-branch e05db0fd v1.5.0-rc0 v1.5.0-rc1 v1.5.0-rc2<br> |
| 351 | ! [e05db0fd] Fix warnings in sha1_file.c - use C99 printf format if<br> |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 352 | available<br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 353 | ! [v1.5.0-rc0] GIT v1.5.0 preview<br> |
| 354 | ! [v1.5.0-rc1] GIT v1.5.0-rc1<br> |
| 355 | ! [v1.5.0-rc2] GIT v1.5.0-rc2<br> |
| 356 | ...</p></div><p>then search for a line that looks like</p><div class="literallayout"><p>+ ++ [e05db0fd] Fix warnings in sha1_file.c - use C99 printf format if<br> |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 357 | available</p></div><p>Which shows that e05db0fd is reachable from itself, from v1.5.0-rc1, and |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 358 | from v1.5.0-rc2, but not from v1.5.0-rc0.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="showing-commits-unique-to-a-branch"></a>Showing commits unique to a given branch</h3></div></div></div><p>Suppose you would like to see all the commits reachable from the branch |
| 359 | head named "master" but not from any other head in your repository.</p><p>We can list all the heads in this repository with |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 360 | <a href="git-show-ref.html" target="_top">git-show-ref(1)</a>:</p><div class="literallayout"><p>$ git show-ref --heads<br> |
| 361 | bf62196b5e363d73353a9dcf094c59595f3153b7 refs/heads/core-tutorial<br> |
| 362 | db768d5504c1bb46f63ee9d6e1772bd047e05bf9 refs/heads/maint<br> |
| 363 | a07157ac624b2524a059a3414e99f6f44bebc1e7 refs/heads/master<br> |
| 364 | 24dbc180ea14dc1aebe09f14c8ecf32010690627 refs/heads/tutorial-2<br> |
| 365 | 1e87486ae06626c2f31eaa63d26fc0fd646c8af2 refs/heads/tutorial-fixes</p></div><p>We can get just the branch-head names, and remove "master", with |
| 366 | the help of the standard utilities cut and grep:</p><div class="literallayout"><p>$ git show-ref --heads | cut -d' ' -f2 | grep -v '^refs/heads/master'<br> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 367 | refs/heads/core-tutorial<br> |
| 368 | refs/heads/maint<br> |
| 369 | refs/heads/tutorial-2<br> |
| 370 | refs/heads/tutorial-fixes</p></div><p>And then we can ask to see all the commits reachable from master |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 371 | but not from these other heads:</p><div class="literallayout"><p>$ gitk master --not $( git show-ref --heads | cut -d' ' -f2 |<br> |
| 372 | grep -v '^refs/heads/master' )</p></div><p>Obviously, endless variations are possible; for example, to see all |
| 373 | commits reachable from some head but not from any tag in the repository:</p><div class="literallayout"><p>$ gitk $( git show-ref --heads ) --not $( git show-ref --tags )</p></div><p>(See <a href="git-rev-parse.html" target="_top">git-rev-parse(1)</a> for explanations of commit-selecting |
| 374 | syntax such as <code class="literal">—not</code>.)</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="making-a-release"></a>Creating a changelog and tarball for a software release</h3></div></div></div><p>The <a href="git-archive.html" target="_top">git-archive(1)</a> command can create a tar or zip archive from |
| 375 | any version of a project; for example:</p><div class="literallayout"><p>$ git archive --format=tar --prefix=project/ HEAD | gzip >latest.tar.gz</p></div><p>will use HEAD to produce a tar archive in which each filename is |
| Junio C Hamano | 2a8f6dc | 2007-07-09 08:48:38 | [diff] [blame] | 376 | preceded by "project/".</p><p>If you're releasing a new version of a software project, you may want |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 377 | to simultaneously make a changelog to include in the release |
| 378 | announcement.</p><p>Linus Torvalds, for example, makes new kernel releases by tagging them, |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 379 | then running:</p><div class="literallayout"><p>$ release-script 2.6.12 2.6.13-rc6 2.6.13-rc7</p></div><p>where release-script is a shell script that looks like:</p><div class="literallayout"><p>#!/bin/sh<br> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 380 | stable="$1"<br> |
| 381 | last="$2"<br> |
| 382 | new="$3"<br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 383 | echo "# git tag v$new"<br> |
| 384 | echo "git archive --prefix=linux-$new/ v$new | gzip -9 > ../linux-$new.tar.gz"<br> |
| 385 | echo "git diff v$stable v$new | gzip -9 > ../patch-$new.gz"<br> |
| 386 | echo "git log --no-merges v$new ^v$last > ../ChangeLog-$new"<br> |
| 387 | echo "git shortlog --no-merges v$new ^v$last > ../ShortLog"<br> |
| 388 | echo "git diff --stat --summary -M v$last v$new > ../diffstat-$new"</p></div><p>and then he just cut-and-pastes the output commands after verifying that |
| Junio C Hamano | 8b8b0f2 | 2007-08-26 22:10:26 | [diff] [blame] | 389 | they look OK.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="Finding-comments-with-given-content"></a>Finding commits referencing a file with given content</h3></div></div></div><p>Somebody hands you a copy of a file, and asks which commits modified a |
| Junio C Hamano | ed7f4f6 | 2007-05-20 09:09:09 | [diff] [blame] | 390 | file such that it contained the given content either before or after the |
| Junio C Hamano | 764a667 | 2007-10-23 01:23:31 | [diff] [blame] | 391 | commit. You can find out with this:</p><div class="literallayout"><p>$ git log --raw --abbrev=40 --pretty=oneline |<br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 392 | grep -B 1 `git hash-object filename`</p></div><p>Figuring out why this works is left as an exercise to the (advanced) |
| Junio C Hamano | ed7f4f6 | 2007-05-20 09:09:09 | [diff] [blame] | 393 | student. The <a href="git-log.html" target="_top">git-log(1)</a>, <a href="git-diff-tree.html" target="_top">git-diff-tree(1)</a>, and |
| Junio C Hamano | ce3650e | 2007-11-26 04:20:11 | [diff] [blame] | 394 | <a href="git-hash-object.html" target="_top">git-hash-object(1)</a> man pages may prove helpful.</p></div></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="Developing-with-git"></a>Chapter 3. Developing with git</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="section"><a href="#telling-git-your-name">Telling git your name</a></span></dt><dt><span class="section"><a href="#creating-a-new-repository">Creating a new repository</a></span></dt><dt><span class="section"><a href="#how-to-make-a-commit">How to make a commit</a></span></dt><dt><span class="section"><a href="#creating-good-commit-messages">Creating good commit messages</a></span></dt><dt><span class="section"><a href="#ignoring-files">Ignoring files</a></span></dt><dt><span class="section"><a href="#how-to-merge">How to merge</a></span></dt><dt><span class="section"><a href="#resolving-a-merge">Resolving a merge</a></span></dt><dd><dl><dt><span class="section"><a href="#conflict-resolution">Getting conflict-resolution help during a merge</a></span></dt></dl></dd><dt><span class="section"><a href="#undoing-a-merge">Undoing a merge</a></span></dt><dt><span class="section"><a href="#fast-forwards">Fast-forward merges</a></span></dt><dt><span class="section"><a href="#fixing-mistakes">Fixing mistakes</a></span></dt><dd><dl><dt><span class="section"><a href="#reverting-a-commit">Fixing a mistake with a new commit</a></span></dt><dt><span class="section"><a href="#fixing-a-mistake-by-rewriting-history">Fixing a mistake by rewriting history</a></span></dt><dt><span class="section"><a href="#checkout-of-path">Checking out an old version of a file</a></span></dt><dt><span class="section"><a href="#interrupted-work">Temporarily setting aside work in progress</a></span></dt></dl></dd><dt><span class="section"><a href="#ensuring-good-performance">Ensuring good performance</a></span></dt><dt><span class="section"><a href="#ensuring-reliability">Ensuring reliability</a></span></dt><dd><dl><dt><span class="section"><a href="#checking-for-corruption">Checking the repository for corruption</a></span></dt><dt><span class="section"><a href="#recovering-lost-changes">Recovering lost changes</a></span></dt></dl></dd></dl></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="telling-git-your-name"></a>Telling git your name</h2></div></div></div><p>Before creating any commits, you should introduce yourself to git. The |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 395 | easiest way to do so is to make sure the following lines appear in a |
| 396 | file named .gitconfig in your home directory:</p><div class="literallayout"><p>[user]<br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 397 | name = Your Name Comes Here<br> |
| 398 | email = you@yourdomain.example.com</p></div><p>(See the "CONFIGURATION FILE" section of <a href="git-config.html" target="_top">git-config(1)</a> for |
| 399 | details on the configuration file.)</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="creating-a-new-repository"></a>Creating a new repository</h2></div></div></div><p>Creating a new repository from scratch is very easy:</p><div class="literallayout"><p>$ mkdir project<br> |
| 400 | $ cd project<br> |
| 401 | $ git init</p></div><p>If you have some initial content (say, a tarball):</p><div class="literallayout"><p>$ tar -xzvf project.tar.gz<br> |
| 402 | $ cd project<br> |
| 403 | $ git init<br> |
| 404 | $ git add . # include everything below ./ in the first commit:<br> |
| 405 | $ git commit</p></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="how-to-make-a-commit"></a>How to make a commit</h2></div></div></div><p>Creating a new commit takes three steps:</p><div class="orderedlist"><ol type="1"><li> |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 406 | Making some changes to the working directory using your |
| 407 | favorite editor. |
| 408 | </li><li> |
| 409 | Telling git about your changes. |
| 410 | </li><li> |
| 411 | Creating the commit using the content you told git about |
| 412 | in step 2. |
| 413 | </li></ol></div><p>In practice, you can interleave and repeat steps 1 and 2 as many |
| 414 | times as you want: in order to keep track of what you want committed |
| 415 | at step 3, git maintains a snapshot of the tree's contents in a |
| 416 | special staging area called "the index."</p><p>At the beginning, the content of the index will be identical to |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 417 | that of the HEAD. The command "git diff —cached", which shows |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 418 | the difference between the HEAD and the index, should therefore |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 419 | produce no output at that point.</p><p>Modifying the index is easy:</p><p>To update the index with the new contents of a modified file, use</p><div class="literallayout"><p>$ git add path/to/file</p></div><p>To add the contents of a new file to the index, use</p><div class="literallayout"><p>$ git add path/to/file</p></div><p>To remove a file from the index and from the working tree,</p><div class="literallayout"><p>$ git rm path/to/file</p></div><p>After each step you can verify that</p><div class="literallayout"><p>$ git diff --cached</p></div><p>always shows the difference between the HEAD and the index file—this |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 420 | is what you'd commit if you created the commit now—and that</p><div class="literallayout"><p>$ git diff</p></div><p>shows the difference between the working tree and the index file.</p><p>Note that "git-add" always adds just the current contents of a file |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 421 | to the index; further changes to the same file will be ignored unless |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 422 | you run git-add on the file again.</p><p>When you're ready, just run</p><div class="literallayout"><p>$ git commit</p></div><p>and git will prompt you for a commit message and then create the new |
| 423 | commit. Check to make sure it looks like what you expected with</p><div class="literallayout"><p>$ git show</p></div><p>As a special shortcut,</p><div class="literallayout"><p>$ git commit -a</p></div><p>will update the index with any files that you've modified or removed |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 424 | and create a commit, all in one step.</p><p>A number of commands are useful for keeping track of what you're |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 425 | about to commit:</p><div class="literallayout"><p>$ git diff --cached # difference between HEAD and the index; what<br> |
| 426 | # would be committed if you ran "commit" now.<br> |
| 427 | $ git diff # difference between the index file and your<br> |
| 428 | # working directory; changes that would not<br> |
| 429 | # be included if you ran "commit" now.<br> |
| 430 | $ git diff HEAD # difference between HEAD and working tree; what<br> |
| 431 | # would be committed if you ran "commit -a" now.<br> |
| Junio C Hamano | 4cd1c0e | 2007-08-06 04:39:14 | [diff] [blame] | 432 | $ git status # a brief per-file summary of the above.</p></div><p>You can also use <a href="git-gui.html" target="_top">git-gui(1)</a> to create commits, view changes in |
| 433 | the index and the working tree files, and individually select diff hunks |
| 434 | for inclusion in the index (by right-clicking on the diff hunk and |
| 435 | choosing "Stage Hunk For Commit").</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="creating-good-commit-messages"></a>Creating good commit messages</h2></div></div></div><p>Though not required, it's a good idea to begin the commit message |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 436 | with a single short (less than 50 character) line summarizing the |
| 437 | change, followed by a blank line and then a more thorough |
| 438 | description. Tools that turn commits into email, for example, use |
| 439 | the first line on the Subject line and the rest of the commit in the |
| Junio C Hamano | ed7f4f6 | 2007-05-20 09:09:09 | [diff] [blame] | 440 | body.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="ignoring-files"></a>Ignoring files</h2></div></div></div><p>A project will often generate files that you do <span class="emphasis"><em>not</em></span> want to track with git. |
| 441 | This typically includes files generated by a build process or temporary |
| 442 | backup files made by your editor. Of course, <span class="emphasis"><em>not</em></span> tracking files with git |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 443 | is just a matter of <span class="emphasis"><em>not</em></span> calling "<code class="literal">git-add</code>" on them. But it quickly becomes |
| Junio C Hamano | ed7f4f6 | 2007-05-20 09:09:09 | [diff] [blame] | 444 | annoying to have these untracked files lying around; e.g. they make |
| 445 | "<code class="literal">git add .</code>" and "<code class="literal">git commit -a</code>" practically useless, and they keep |
| Junio C Hamano | 8b8b0f2 | 2007-08-26 22:10:26 | [diff] [blame] | 446 | showing up in the output of "<code class="literal">git status</code>".</p><p>You can tell git to ignore certain files by creating a file called .gitignore |
| 447 | in the top level of your working directory, with contents such as:</p><div class="literallayout"><p># Lines starting with '#' are considered comments.<br> |
| 448 | # Ignore any file named foo.txt.<br> |
| Junio C Hamano | ed7f4f6 | 2007-05-20 09:09:09 | [diff] [blame] | 449 | foo.txt<br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 450 | # Ignore (generated) html files,<br> |
| Junio C Hamano | ed7f4f6 | 2007-05-20 09:09:09 | [diff] [blame] | 451 | *.html<br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 452 | # except foo.html which is maintained by hand.<br> |
| Junio C Hamano | ed7f4f6 | 2007-05-20 09:09:09 | [diff] [blame] | 453 | !foo.html<br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 454 | # Ignore objects and archives.<br> |
| Junio C Hamano | 8b8b0f2 | 2007-08-26 22:10:26 | [diff] [blame] | 455 | *.[oa]</p></div><p>See <a href="gitignore.html" target="_top">gitignore(5)</a> for a detailed explanation of the syntax. You can |
| 456 | also place .gitignore files in other directories in your working tree, and they |
| 457 | will apply to those directories and their subdirectories. The <code class="literal">.gitignore</code> |
| 458 | files can be added to your repository like any other files (just run <code class="literal">git add |
| 459 | .gitignore</code> and <code class="literal">git commit</code>, as usual), which is convenient when the exclude |
| 460 | patterns (such as patterns matching build output files) would also make sense |
| 461 | for other users who clone your repository.</p><p>If you wish the exclude patterns to affect only certain repositories |
| 462 | (instead of every repository for a given project), you may instead put |
| 463 | them in a file in your repository named .git/info/exclude, or in any file |
| 464 | specified by the <code class="literal">core.excludesfile</code> configuration variable. Some git |
| 465 | commands can also take exclude patterns directly on the command line. |
| 466 | See <a href="gitignore.html" target="_top">gitignore(5)</a> for the details.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="how-to-merge"></a>How to merge</h2></div></div></div><p>You can rejoin two diverging branches of development using |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 467 | <a href="git-merge.html" target="_top">git-merge(1)</a>:</p><div class="literallayout"><p>$ git merge branchname</p></div><p>merges the development in the branch "branchname" into the current |
| 468 | branch. If there are conflicts—for example, if the same file is |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 469 | modified in two different ways in the remote branch and the local |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 470 | branch—then you are warned; the output may look something like this:</p><div class="literallayout"><p>$ git merge next<br> |
| 471 | 100% (4/4) done<br> |
| 472 | Auto-merged file.txt<br> |
| 473 | CONFLICT (content): Merge conflict in file.txt<br> |
| 474 | Automatic merge failed; fix conflicts and then commit the result.</p></div><p>Conflict markers are left in the problematic files, and after |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 475 | you resolve the conflicts manually, you can update the index |
| 476 | with the contents and run git commit, as you normally would when |
| 477 | creating a new file.</p><p>If you examine the resulting commit using gitk, you will see that it |
| 478 | has two parents, one pointing to the top of the current branch, and |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 479 | one to the top of the other branch.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="resolving-a-merge"></a>Resolving a merge</h2></div></div></div><p>When a merge isn't resolved automatically, git leaves the index and |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 480 | the working tree in a special state that gives you all the |
| 481 | information you need to help resolve the merge.</p><p>Files with conflicts are marked specially in the index, so until you |
| Junio C Hamano | aa83a7d | 2007-03-05 02:37:29 | [diff] [blame] | 482 | resolve the problem and update the index, <a href="git-commit.html" target="_top">git-commit(1)</a> will |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 483 | fail:</p><div class="literallayout"><p>$ git commit<br> |
| 484 | file.txt: needs merge</p></div><p>Also, <a href="git-status.html" target="_top">git-status(1)</a> will list those files as "unmerged", and the |
| 485 | files with conflicts will have conflict markers added, like this:</p><div class="literallayout"><p><<<<<<< HEAD:file.txt<br> |
| 486 | Hello world<br> |
| Junio C Hamano | aa83a7d | 2007-03-05 02:37:29 | [diff] [blame] | 487 | =======<br> |
| 488 | Goodbye<br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 489 | >>>>>>> 77976da35a11db4580b80ae27e8d65caf5208086:file.txt</p></div><p>All you need to do is edit the files to resolve the conflicts, and then</p><div class="literallayout"><p>$ git add file.txt<br> |
| 490 | $ git commit</p></div><p>Note that the commit message will already be filled in for you with |
| Junio C Hamano | aa83a7d | 2007-03-05 02:37:29 | [diff] [blame] | 491 | some information about the merge. Normally you can just use this |
| 492 | default message unchanged, but you may add additional commentary of |
| 493 | your own if desired.</p><p>The above is all you need to know to resolve a simple merge. But git |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 494 | also provides more information to help resolve conflicts:</p><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="conflict-resolution"></a>Getting conflict-resolution help during a merge</h3></div></div></div><p>All of the changes that git was able to merge automatically are |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 495 | already added to the index file, so <a href="git-diff.html" target="_top">git-diff(1)</a> shows only |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 496 | the conflicts. It uses an unusual syntax:</p><div class="literallayout"><p>$ git diff<br> |
| 497 | diff --cc file.txt<br> |
| 498 | index 802992c,2b60207..0000000<br> |
| 499 | --- a/file.txt<br> |
| 500 | +++ b/file.txt<br> |
| 501 | @@@ -1,1 -1,1 +1,5 @@@<br> |
| 502 | ++<<<<<<< HEAD:file.txt<br> |
| 503 | +Hello world<br> |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 504 | ++=======<br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 505 | + Goodbye<br> |
| 506 | ++>>>>>>> 77976da35a11db4580b80ae27e8d65caf5208086:file.txt</p></div><p>Recall that the commit which will be committed after we resolve this |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 507 | conflict will have two parents instead of the usual one: one parent |
| 508 | will be HEAD, the tip of the current branch; the other will be the |
| Junio C Hamano | aa83a7d | 2007-03-05 02:37:29 | [diff] [blame] | 509 | tip of the other branch, which is stored temporarily in MERGE_HEAD.</p><p>During the merge, the index holds three versions of each file. Each of |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 510 | these three "file stages" represents a different version of the file:</p><div class="literallayout"><p>$ git show :1:file.txt # the file in a common ancestor of both branches<br> |
| Junio C Hamano | 6fb124c | 2008-06-13 10:04:01 | [diff] [blame] | 511 | $ git show :2:file.txt # the version from HEAD.<br> |
| 512 | $ git show :3:file.txt # the version from MERGE_HEAD.</p></div><p>When you ask <a href="git-diff.html" target="_top">git-diff(1)</a> to show the conflicts, it runs a |
| 513 | three-way diff between the conflicted merge results in the work tree with |
| 514 | stages 2 and 3 to show only hunks whose contents come from both sides, |
| 515 | mixed (in other words, when a hunk's merge results come only from stage 2, |
| 516 | that part is not conflicting and is not shown. Same for stage 3).</p><p>The diff above shows the differences between the working-tree version of |
| Junio C Hamano | aa83a7d | 2007-03-05 02:37:29 | [diff] [blame] | 517 | file.txt and the stage 2 and stage 3 versions. So instead of preceding |
| 518 | each line by a single "+" or "-", it now uses two columns: the first |
| 519 | column is used for differences between the first parent and the working |
| 520 | directory copy, and the second for differences between the second parent |
| 521 | and the working directory copy. (See the "COMBINED DIFF FORMAT" section |
| 522 | of <a href="git-diff-files.html" target="_top">git-diff-files(1)</a> for a details of the format.)</p><p>After resolving the conflict in the obvious way (but before updating the |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 523 | index), the diff will look like:</p><div class="literallayout"><p>$ git diff<br> |
| 524 | diff --cc file.txt<br> |
| 525 | index 802992c,2b60207..0000000<br> |
| 526 | --- a/file.txt<br> |
| 527 | +++ b/file.txt<br> |
| 528 | @@@ -1,1 -1,1 +1,1 @@@<br> |
| 529 | - Hello world<br> |
| 530 | -Goodbye<br> |
| 531 | ++Goodbye world</p></div><p>This shows that our resolved version deleted "Hello world" from the |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 532 | first parent, deleted "Goodbye" from the second parent, and added |
| Junio C Hamano | aa83a7d | 2007-03-05 02:37:29 | [diff] [blame] | 533 | "Goodbye world", which was previously absent from both.</p><p>Some special diff options allow diffing the working directory against |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 534 | any of these stages:</p><div class="literallayout"><p>$ git diff -1 file.txt # diff against stage 1<br> |
| 535 | $ git diff --base file.txt # same as the above<br> |
| 536 | $ git diff -2 file.txt # diff against stage 2<br> |
| 537 | $ git diff --ours file.txt # same as the above<br> |
| 538 | $ git diff -3 file.txt # diff against stage 3<br> |
| 539 | $ git diff --theirs file.txt # same as the above.</p></div><p>The <a href="git-log.html" target="_top">git-log(1)</a> and gitk[1] commands also provide special help |
| 540 | for merges:</p><div class="literallayout"><p>$ git log --merge<br> |
| 541 | $ gitk --merge</p></div><p>These will display all commits which exist only on HEAD or on |
| Junio C Hamano | ec47dcf | 2007-05-16 22:46:31 | [diff] [blame] | 542 | MERGE_HEAD, and which touch an unmerged file.</p><p>You may also use <a href="git-mergetool.html" target="_top">git-mergetool(1)</a>, which lets you merge the |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 543 | unmerged files using external tools such as emacs or kdiff3.</p><p>Each time you resolve the conflicts in a file and update the index:</p><div class="literallayout"><p>$ git add file.txt</p></div><p>the different stages of that file will be "collapsed", after which |
| Junio C Hamano | 12a3a23 | 2007-04-07 10:18:10 | [diff] [blame] | 544 | git-diff will (by default) no longer show diffs for that file.</p></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="undoing-a-merge"></a>Undoing a merge</h2></div></div></div><p>If you get stuck and decide to just give up and throw the whole mess |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 545 | away, you can always return to the pre-merge state with</p><div class="literallayout"><p>$ git reset --hard HEAD</p></div><p>Or, if you've already committed the merge that you want to throw away,</p><div class="literallayout"><p>$ git reset --hard ORIG_HEAD</p></div><p>However, this last command can be dangerous in some cases—never |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 546 | throw away a commit you have already committed if that commit may |
| 547 | itself have been merged into another branch, as doing so may confuse |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 548 | further merges.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="fast-forwards"></a>Fast-forward merges</h2></div></div></div><p>There is one special case not mentioned above, which is treated |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 549 | differently. Normally, a merge results in a merge commit, with two |
| 550 | parents, one pointing at each of the two lines of development that |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 551 | were merged.</p><p>However, if the current branch is a descendant of the other—so every |
| 552 | commit present in the one is already contained in the other—then git |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 553 | just performs a "fast forward"; the head of the current branch is moved |
| 554 | forward to point at the head of the merged-in branch, without any new |
| 555 | commits being created.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="fixing-mistakes"></a>Fixing mistakes</h2></div></div></div><p>If you've messed up the working tree, but haven't yet committed your |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 556 | mistake, you can return the entire working tree to the last committed |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 557 | state with</p><div class="literallayout"><p>$ git reset --hard HEAD</p></div><p>If you make a commit that you later wish you hadn't, there are two |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 558 | fundamentally different ways to fix the problem:</p><div class="orderedlist"><ol type="1"><li> |
| 559 | You can create a new commit that undoes whatever was done |
| Junio C Hamano | 8c5802d | 2007-11-15 00:13:36 | [diff] [blame] | 560 | by the old commit. This is the correct thing if your |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 561 | mistake has already been made public. |
| 562 | </li><li> |
| 563 | You can go back and modify the old commit. You should |
| 564 | never do this if you have already made the history public; |
| 565 | git does not normally expect the "history" of a project to |
| 566 | change, and cannot correctly perform repeated merges from |
| 567 | a branch that has had its history changed. |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 568 | </li></ol></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="reverting-a-commit"></a>Fixing a mistake with a new commit</h3></div></div></div><p>Creating a new commit that reverts an earlier change is very easy; |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 569 | just pass the <a href="git-revert.html" target="_top">git-revert(1)</a> command a reference to the bad |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 570 | commit; for example, to revert the most recent commit:</p><div class="literallayout"><p>$ git revert HEAD</p></div><p>This will create a new commit which undoes the change in HEAD. You |
| 571 | will be given a chance to edit the commit message for the new commit.</p><p>You can also revert an earlier change, for example, the next-to-last:</p><div class="literallayout"><p>$ git revert HEAD^</p></div><p>In this case git will attempt to undo the old change while leaving |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 572 | intact any changes made since then. If more recent changes overlap |
| 573 | with the changes to be reverted, then you will be asked to fix |
| Junio C Hamano | ce3650e | 2007-11-26 04:20:11 | [diff] [blame] | 574 | conflicts manually, just as in the case of <a href="#resolving-a-merge" title="Resolving a merge">resolving a merge</a>.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="fixing-a-mistake-by-rewriting-history"></a>Fixing a mistake by rewriting history</h3></div></div></div><p>If the problematic commit is the most recent commit, and you have not |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 575 | yet made that commit public, then you may just |
| Junio C Hamano | 12a3a23 | 2007-04-07 10:18:10 | [diff] [blame] | 576 | <a href="#undoing-a-merge" title="Undoing a merge">destroy it using git-reset</a>.</p><p>Alternatively, you |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 577 | can edit the working directory and update the index to fix your |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 578 | mistake, just as if you were going to <a href="#how-to-make-a-commit" title="How to make a commit">create a new commit</a>, then run</p><div class="literallayout"><p>$ git commit --amend</p></div><p>which will replace the old commit by a new commit incorporating your |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 579 | changes, giving you a chance to edit the old commit message first.</p><p>Again, you should never do this to a commit that may already have |
| 580 | been merged into another branch; use <a href="git-revert.html" target="_top">git-revert(1)</a> instead in |
| Junio C Hamano | ce3650e | 2007-11-26 04:20:11 | [diff] [blame] | 581 | that case.</p><p>It is also possible to replace commits further back in the history, but |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 582 | this is an advanced topic to be left for |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 583 | <a href="#cleaning-up-history" title="Chapter 5. Rewriting history and maintaining patch series">another chapter</a>.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="checkout-of-path"></a>Checking out an old version of a file</h3></div></div></div><p>In the process of undoing a previous bad change, you may find it |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 584 | useful to check out an older version of a particular file using |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 585 | <a href="git-checkout.html" target="_top">git-checkout(1)</a>. We've used git-checkout before to switch |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 586 | branches, but it has quite different behavior if it is given a path |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 587 | name: the command</p><div class="literallayout"><p>$ git checkout HEAD^ path/to/file</p></div><p>replaces path/to/file by the contents it had in the commit HEAD^, and |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 588 | also updates the index to match. It does not change branches.</p><p>If you just want to look at an old version of the file, without |
| 589 | modifying the working directory, you can do that with |
| Junio C Hamano | 4cd1c0e | 2007-08-06 04:39:14 | [diff] [blame] | 590 | <a href="git-show.html" target="_top">git-show(1)</a>:</p><div class="literallayout"><p>$ git show HEAD^:path/to/file</p></div><p>which will display the given version of the file.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="interrupted-work"></a>Temporarily setting aside work in progress</h3></div></div></div><p>While you are in the middle of working on something complicated, you |
| 591 | find an unrelated but obvious and trivial bug. You would like to fix it |
| 592 | before continuing. You can use <a href="git-stash.html" target="_top">git-stash(1)</a> to save the current |
| 593 | state of your work, and after fixing the bug (or, optionally after doing |
| 594 | so on a different branch and then coming back), unstash the |
| 595 | work-in-progress changes.</p><div class="literallayout"><p>$ git stash "work in progress for foo feature"</p></div><p>This command will save your changes away to the <code class="literal">stash</code>, and |
| 596 | reset your working tree and the index to match the tip of your |
| 597 | current branch. Then you can make your fix as usual.</p><div class="literallayout"><p>... edit and test ...<br> |
| 598 | $ git commit -a -m "blorpl: typofix"</p></div><p>After that, you can go back to what you were working on with |
| 599 | <code class="literal">git stash apply</code>:</p><div class="literallayout"><p>$ git stash apply</p></div></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="ensuring-good-performance"></a>Ensuring good performance</h2></div></div></div><p>On large repositories, git depends on compression to keep the history |
| Junio C Hamano | 764a667 | 2007-10-23 01:23:31 | [diff] [blame] | 600 | information from taking up too much space on disk or in memory.</p><p>This compression is not performed automatically. Therefore you |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 601 | should occasionally run <a href="git-gc.html" target="_top">git-gc(1)</a>:</p><div class="literallayout"><p>$ git gc</p></div><p>to recompress the archive. This can be very time-consuming, so |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 602 | you may prefer to run git-gc when you are not doing other work.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="ensuring-reliability"></a>Ensuring reliability</h2></div></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="checking-for-corruption"></a>Checking the repository for corruption</h3></div></div></div><p>The <a href="git-fsck.html" target="_top">git-fsck(1)</a> command runs a number of self-consistency checks |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 603 | on the repository, and reports on any problems. This may take some |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 604 | time. The most common warning by far is about "dangling" objects:</p><div class="literallayout"><p>$ git fsck<br> |
| 605 | dangling commit 7281251ddd2a61e38657c827739c57015671a6b3<br> |
| 606 | dangling commit 2706a059f258c6b245f298dc4ff2ccd30ec21a63<br> |
| 607 | dangling commit 13472b7c4b80851a1bc551779171dcb03655e9b5<br> |
| 608 | dangling blob 218761f9d90712d37a9c5e36f406f92202db07eb<br> |
| 609 | dangling commit bf093535a34a4d35731aa2bd90fe6b176302f14f<br> |
| 610 | dangling commit 8e4bec7f2ddaa268bef999853c25755452100f8e<br> |
| 611 | dangling tree d50bb86186bf27b681d25af89d3b5b68382e4085<br> |
| 612 | dangling tree b24c2473f1fd3d91352a624795be026d64c8841f<br> |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 613 | ...</p></div><p>Dangling objects are not a problem. At worst they may take up a little |
| Junio C Hamano | 2a8f6dc | 2007-07-09 08:48:38 | [diff] [blame] | 614 | extra disk space. They can sometimes provide a last-resort method for |
| Junio C Hamano | a9aee78 | 2008-04-23 16:09:20 | [diff] [blame] | 615 | recovering lost work—see <a href="#dangling-objects" title="Dangling objects">the section called “Dangling objects”</a> for details.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="recovering-lost-changes"></a>Recovering lost changes</h3></div></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="reflogs"></a>Reflogs</h4></div></div></div><p>Say you modify a branch with <code class="literal"><a href="git-reset.html" target="_top">git-reset(1)</a> —hard</code>, and then |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 616 | realize that the branch was the only reference you had to that point in |
| 617 | history.</p><p>Fortunately, git also keeps a log, called a "reflog", of all the |
| 618 | previous values of each branch. So in this case you can still find the |
| Junio C Hamano | 63777e2 | 2007-11-17 20:52:16 | [diff] [blame] | 619 | old history using, for example,</p><div class="literallayout"><p>$ git log master@{1}</p></div><p>This lists the commits reachable from the previous version of the |
| 620 | "master" branch head. This syntax can be used with any git command |
| 621 | that accepts a commit, not just with git log. Some other examples:</p><div class="literallayout"><p>$ git show master@{2} # See where the branch pointed 2,<br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 622 | $ git show master@{3} # 3, ... changes ago.<br> |
| 623 | $ gitk master@{yesterday} # See where it pointed yesterday,<br> |
| 624 | $ gitk master@{"1 week ago"} # ... or last week<br> |
| 625 | $ git log --walk-reflogs master # show reflog entries for master</p></div><p>A separate reflog is kept for the HEAD, so</p><div class="literallayout"><p>$ git show HEAD@{"1 week ago"}</p></div><p>will show what HEAD pointed to one week ago, not what the current branch |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 626 | pointed to one week ago. This allows you to see the history of what |
| 627 | you've checked out.</p><p>The reflogs are kept by default for 30 days, after which they may be |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 628 | pruned. See <a href="git-reflog.html" target="_top">git-reflog(1)</a> and <a href="git-gc.html" target="_top">git-gc(1)</a> to learn |
| 629 | how to control this pruning, and see the "SPECIFYING REVISIONS" |
| 630 | section of <a href="git-rev-parse.html" target="_top">git-rev-parse(1)</a> for details.</p><p>Note that the reflog history is very different from normal git history. |
| 631 | While normal history is shared by every repository that works on the |
| 632 | same project, the reflog history is not shared: it tells you only about |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 633 | how the branches in your local repository have changed over time.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="dangling-object-recovery"></a>Examining dangling objects</h4></div></div></div><p>In some situations the reflog may not be able to save you. For example, |
| 634 | suppose you delete a branch, then realize you need the history it |
| 635 | contained. The reflog is also deleted; however, if you have not yet |
| 636 | pruned the repository, then you may still be able to find the lost |
| 637 | commits in the dangling objects that git-fsck reports. See |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 638 | <a href="#dangling-objects" title="Dangling objects">the section called “Dangling objects”</a> for the details.</p><div class="literallayout"><p>$ git fsck<br> |
| 639 | dangling commit 7281251ddd2a61e38657c827739c57015671a6b3<br> |
| 640 | dangling commit 2706a059f258c6b245f298dc4ff2ccd30ec21a63<br> |
| 641 | dangling commit 13472b7c4b80851a1bc551779171dcb03655e9b5<br> |
| Junio C Hamano | 39381a7 | 2007-02-02 07:35:15 | [diff] [blame] | 642 | ...</p></div><p>You can examine |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 643 | one of those dangling commits with, for example,</p><div class="literallayout"><p>$ gitk 7281251ddd --not --all</p></div><p>which does what it sounds like: it says that you want to see the commit |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 644 | history that is described by the dangling commit(s), but not the |
| 645 | history that is described by all your existing branches and tags. Thus |
| 646 | you get exactly the history reachable from that commit that is lost. |
| 647 | (And notice that it might not be just one commit: we only report the |
| 648 | "tip of the line" as being dangling, but there might be a whole deep |
| Junio C Hamano | db911ee | 2007-02-28 08:13:52 | [diff] [blame] | 649 | and complex commit history that was dropped.)</p><p>If you decide you want the history back, you can always create a new |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 650 | reference pointing to it, for example, a new branch:</p><div class="literallayout"><p>$ git branch recovered-branch 7281251ddd</p></div><p>Other types of dangling objects (blobs and trees) are also possible, and |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 651 | dangling objects can arise in other situations.</p></div></div></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="sharing-development"></a>Chapter 4. Sharing development with others</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="section"><a href="#getting-updates-with-git-pull">Getting updates with git-pull</a></span></dt><dt><span class="section"><a href="#submitting-patches">Submitting patches to a project</a></span></dt><dt><span class="section"><a href="#importing-patches">Importing patches to a project</a></span></dt><dt><span class="section"><a href="#public-repositories">Public git repositories</a></span></dt><dd><dl><dt><span class="section"><a href="#setting-up-a-public-repository">Setting up a public repository</a></span></dt><dt><span class="section"><a href="#exporting-via-git">Exporting a git repository via the git protocol</a></span></dt><dt><span class="section"><a href="#exporting-via-http">Exporting a git repository via http</a></span></dt><dt><span class="section"><a href="#pushing-changes-to-a-public-repository">Pushing changes to a public repository</a></span></dt><dt><span class="section"><a href="#forcing-push">What to do when a push fails</a></span></dt><dt><span class="section"><a href="#setting-up-a-shared-repository">Setting up a shared repository</a></span></dt><dt><span class="section"><a href="#setting-up-gitweb">Allowing web browsing of a repository</a></span></dt></dl></dd><dt><span class="section"><a href="#sharing-development-examples">Examples</a></span></dt><dd><dl><dt><span class="section"><a href="#maintaining-topic-branches">Maintaining topic branches for a Linux subsystem maintainer</a></span></dt></dl></dd></dl></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="getting-updates-with-git-pull"></a>Getting updates with git-pull</h2></div></div></div><p>After you clone a repository and make a few changes of your own, you |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 652 | may wish to check the original repository for updates and merge them |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 653 | into your own work.</p><p>We have already seen <a href="#Updating-a-repository-with-git-fetch" title="Updating a repository with git-fetch">how to keep remote tracking branches up to date</a> with <a href="git-fetch.html" target="_top">git-fetch(1)</a>, |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 654 | and how to merge two branches. So you can merge in changes from the |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 655 | original repository's master branch with:</p><div class="literallayout"><p>$ git fetch<br> |
| 656 | $ git merge origin/master</p></div><p>However, the <a href="git-pull.html" target="_top">git-pull(1)</a> command provides a way to do this in |
| Junio C Hamano | 4cd1c0e | 2007-08-06 04:39:14 | [diff] [blame] | 657 | one step:</p><div class="literallayout"><p>$ git pull origin master</p></div><p>In fact, if you have "master" checked out, then by default "git pull" |
| 658 | merges from the HEAD branch of the origin repository. So often you can |
| 659 | accomplish the above with just a simple</p><div class="literallayout"><p>$ git pull</p></div><p>More generally, a branch that is created from a remote branch will pull |
| 660 | by default from that branch. See the descriptions of the |
| 661 | branch.<name>.remote and branch.<name>.merge options in |
| Junio C Hamano | 764a667 | 2007-10-23 01:23:31 | [diff] [blame] | 662 | <a href="git-config.html" target="_top">git-config(1)</a>, and the discussion of the <code class="literal">—track</code> option in |
| Junio C Hamano | 4cd1c0e | 2007-08-06 04:39:14 | [diff] [blame] | 663 | <a href="git-checkout.html" target="_top">git-checkout(1)</a>, to learn how to control these defaults.</p><p>In addition to saving you keystrokes, "git pull" also helps you by |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 664 | producing a default commit message documenting the branch and |
| 665 | repository that you pulled from.</p><p>(But note that no such commit will be created in the case of a |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 666 | <a href="#fast-forwards" title="Fast-forward merges">fast forward</a>; instead, your branch will just be |
| Junio C Hamano | db911ee | 2007-02-28 08:13:52 | [diff] [blame] | 667 | updated to point to the latest commit from the upstream branch.)</p><p>The git-pull command can also be given "." as the "remote" repository, |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 668 | in which case it just merges in a branch from the current repository; so |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 669 | the commands</p><div class="literallayout"><p>$ git pull . branch<br> |
| 670 | $ git merge branch</p></div><p>are roughly equivalent. The former is actually very commonly used.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="submitting-patches"></a>Submitting patches to a project</h2></div></div></div><p>If you just have a few changes, the simplest way to submit them may |
| 671 | just be to send them as patches in email:</p><p>First, use <a href="git-format-patch.html" target="_top">git-format-patch(1)</a>; for example:</p><div class="literallayout"><p>$ git format-patch origin</p></div><p>will produce a numbered series of files in the current directory, one |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 672 | for each patch in the current branch but not in origin/HEAD.</p><p>You can then import these into your mail client and send them by |
| 673 | hand. However, if you have a lot to send at once, you may prefer to |
| 674 | use the <a href="git-send-email.html" target="_top">git-send-email(1)</a> script to automate the process. |
| 675 | Consult the mailing list for your project first to determine how they |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 676 | prefer such patches be handled.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="importing-patches"></a>Importing patches to a project</h2></div></div></div><p>Git also provides a tool called <a href="git-am.html" target="_top">git-am(1)</a> (am stands for |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 677 | "apply mailbox"), for importing such an emailed series of patches. |
| 678 | Just save all of the patch-containing messages, in order, into a |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 679 | single mailbox file, say "patches.mbox", then run</p><div class="literallayout"><p>$ git am -3 patches.mbox</p></div><p>Git will apply each patch in order; if any conflicts are found, it |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 680 | will stop, and you can fix the conflicts as described in |
| 681 | "<a href="#resolving-a-merge" title="Resolving a merge">Resolving a merge</a>". (The "-3" option tells |
| 682 | git to perform a merge; if you would prefer it just to abort and |
| 683 | leave your tree and index untouched, you may omit that option.)</p><p>Once the index is updated with the results of the conflict |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 684 | resolution, instead of creating a new commit, just run</p><div class="literallayout"><p>$ git am --resolved</p></div><p>and git will create the commit for you and continue applying the |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 685 | remaining patches from the mailbox.</p><p>The final result will be a series of commits, one for each patch in |
| 686 | the original mailbox, with authorship and commit log message each |
| Junio C Hamano | 8b8b0f2 | 2007-08-26 22:10:26 | [diff] [blame] | 687 | taken from the message containing each patch.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="public-repositories"></a>Public git repositories</h2></div></div></div><p>Another way to submit changes to a project is to tell the maintainer |
| 688 | of that project to pull the changes from your repository using |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 689 | <a href="git-pull.html" target="_top">git-pull(1)</a>. In the section "<a href="#getting-updates-with-git-pull" title="Getting updates with git-pull">Getting updates with git-pull</a>" we described this as a way to get |
| Junio C Hamano | 8b8b0f2 | 2007-08-26 22:10:26 | [diff] [blame] | 690 | updates from the "main" repository, but it works just as well in the |
| 691 | other direction.</p><p>If you and the maintainer both have accounts on the same machine, then |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 692 | you can just pull changes from each other's repositories directly; |
| Junio C Hamano | 2a8f6dc | 2007-07-09 08:48:38 | [diff] [blame] | 693 | commands that accept repository URLs as arguments will also accept a |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 694 | local directory name:</p><div class="literallayout"><p>$ git clone /path/to/repository<br> |
| Junio C Hamano | 764a667 | 2007-10-23 01:23:31 | [diff] [blame] | 695 | $ git pull /path/to/other/repository</p></div><p>or an ssh URL:</p><div class="literallayout"><p>$ git clone ssh://yourhost/~you/repository</p></div><p>For projects with few developers, or for synchronizing a few private |
| Junio C Hamano | 2a8f6dc | 2007-07-09 08:48:38 | [diff] [blame] | 696 | repositories, this may be all you need.</p><p>However, the more common way to do this is to maintain a separate public |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 697 | repository (usually on a different host) for others to pull changes |
| 698 | from. This is usually more convenient, and allows you to cleanly |
| 699 | separate private work in progress from publicly visible work.</p><p>You will continue to do your day-to-day work in your personal |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 700 | repository, but periodically "push" changes from your personal |
| 701 | repository into your public repository, allowing other developers to |
| 702 | pull from that repository. So the flow of changes, in a situation |
| 703 | where there is one other developer with a public repository, looks |
| 704 | like this:</p><pre class="literallayout"> you push |
| 705 | your personal repo ------------------> your public repo |
| 706 | ^ | |
| 707 | | | |
| 708 | | you pull | they pull |
| 709 | | | |
| 710 | | | |
| 711 | | they push V |
| Junio C Hamano | 2a8f6dc | 2007-07-09 08:48:38 | [diff] [blame] | 712 | their public repo <------------------- their repo</pre><p>We explain how to do this in the following sections.</p><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="setting-up-a-public-repository"></a>Setting up a public repository</h3></div></div></div><p>Assume your personal repository is in the directory ~/proj. We |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 713 | first create a new clone of the repository and tell git-daemon that it |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 714 | is meant to be public:</p><div class="literallayout"><p>$ git clone --bare ~/proj proj.git<br> |
| 715 | $ touch proj.git/git-daemon-export-ok</p></div><p>The resulting directory proj.git contains a "bare" git repository—it is |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 716 | just the contents of the ".git" directory, without any files checked out |
| 717 | around it.</p><p>Next, copy proj.git to the server where you plan to host the |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 718 | public repository. You can use scp, rsync, or whatever is most |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 719 | convenient.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="exporting-via-git"></a>Exporting a git repository via the git protocol</h3></div></div></div><p>This is the preferred method.</p><p>If someone else administers the server, they should tell you what |
| Junio C Hamano | 764a667 | 2007-10-23 01:23:31 | [diff] [blame] | 720 | directory to put the repository in, and what git:// URL it will appear |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 721 | at. You can then skip to the section |
| 722 | "<a href="#pushing-changes-to-a-public-repository" title="Pushing changes to a public repository">Pushing changes to a public repository</a>", below.</p><p>Otherwise, all you need to do is start <a href="git-daemon.html" target="_top">git-daemon(1)</a>; it will |
| 723 | listen on port 9418. By default, it will allow access to any directory |
| 724 | that looks like a git directory and contains the magic file |
| 725 | git-daemon-export-ok. Passing some directory paths as git-daemon |
| 726 | arguments will further restrict the exports to those paths.</p><p>You can also run git-daemon as an inetd service; see the |
| 727 | <a href="git-daemon.html" target="_top">git-daemon(1)</a> man page for details. (See especially the |
| 728 | examples section.)</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="exporting-via-http"></a>Exporting a git repository via http</h3></div></div></div><p>The git protocol gives better performance and reliability, but on a |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 729 | host with a web server set up, http exports may be simpler to set up.</p><p>All you need to do is place the newly created bare git repository in |
| 730 | a directory that is exported by the web server, and make some |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 731 | adjustments to give web clients some extra information they need:</p><div class="literallayout"><p>$ mv proj.git /home/you/public_html/proj.git<br> |
| 732 | $ cd proj.git<br> |
| 733 | $ git --bare update-server-info<br> |
| 734 | $ chmod a+x hooks/post-update</p></div><p>(For an explanation of the last two lines, see |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 735 | <a href="git-update-server-info.html" target="_top">git-update-server-info(1)</a> and <a href="githooks.html" target="_top">githooks(5)</a>.)</p><p>Advertise the URL of proj.git. Anybody else should then be able to |
| Junio C Hamano | 764a667 | 2007-10-23 01:23:31 | [diff] [blame] | 736 | clone or pull from that URL, for example with a command line like:</p><div class="literallayout"><p>$ git clone http://yourserver.com/~you/proj.git</p></div><p>(See also |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 737 | <a href="howto/setup-git-server-over-http.txt" target="_top">setup-git-server-over-http</a> |
| 738 | for a slightly more sophisticated setup using WebDAV which also |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 739 | allows pushing over http.)</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="pushing-changes-to-a-public-repository"></a>Pushing changes to a public repository</h3></div></div></div><p>Note that the two techniques outlined above (exporting via |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 740 | <a href="#exporting-via-http" title="Exporting a git repository via http">http</a> or <a href="#exporting-via-git" title="Exporting a git repository via the git protocol">git</a>) allow other |
| 741 | maintainers to fetch your latest changes, but they do not allow write |
| 742 | access, which you will need to update the public repository with the |
| 743 | latest changes created in your private repository.</p><p>The simplest way to do this is using <a href="git-push.html" target="_top">git-push(1)</a> and ssh; to |
| 744 | update the remote branch named "master" with the latest state of your |
| Junio C Hamano | ce3650e | 2007-11-26 04:20:11 | [diff] [blame] | 745 | branch named "master", run</p><div class="literallayout"><p>$ git push ssh://yourserver.com/~you/proj.git master:master</p></div><p>or just</p><div class="literallayout"><p>$ git push ssh://yourserver.com/~you/proj.git master</p></div><p>As with git-fetch, git-push will complain if this does not result in a |
| 746 | <a href="#fast-forwards" title="Fast-forward merges">fast forward</a>; see the following section for details on |
| 747 | handling this case.</p><p>Note that the target of a "push" is normally a |
| Junio C Hamano | 2a8f6dc | 2007-07-09 08:48:38 | [diff] [blame] | 748 | <a href="#def_bare_repository">bare</a> repository. You can also push to a |
| 749 | repository that has a checked-out working tree, but the working tree |
| 750 | will not be updated by the push. This may lead to unexpected results if |
| 751 | the branch you push to is the currently checked-out branch!</p><p>As with git-fetch, you may also set up configuration options to |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 752 | save typing; so, for example, after</p><div class="literallayout"><p>$ cat >>.git/config <<EOF<br> |
| 753 | [remote "public-repo"]<br> |
| 754 | url = ssh://yourserver.com/~you/proj.git<br> |
| 755 | EOF</p></div><p>you should be able to perform the above push with just</p><div class="literallayout"><p>$ git push public-repo master</p></div><p>See the explanations of the remote.<name>.url, branch.<name>.remote, |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 756 | and remote.<name>.push options in <a href="git-config.html" target="_top">git-config(1)</a> for |
| Junio C Hamano | ce3650e | 2007-11-26 04:20:11 | [diff] [blame] | 757 | details.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="forcing-push"></a>What to do when a push fails</h3></div></div></div><p>If a push would not result in a <a href="#fast-forwards" title="Fast-forward merges">fast forward</a> of the |
| 758 | remote branch, then it will fail with an error like:</p><div class="literallayout"><p>error: remote 'refs/heads/master' is not an ancestor of<br> |
| 759 | local 'refs/heads/master'.<br> |
| 760 | Maybe you are not up-to-date and need to pull first?<br> |
| 761 | error: failed to push to 'ssh://yourserver.com/~you/proj.git'</p></div><p>This can happen, for example, if you:</p><div class="itemizedlist"><ul type="disc"><li> |
| 762 | use <code class="literal">git reset —hard</code> to remove already-published commits, or |
| 763 | </li><li> |
| 764 | use <code class="literal">git commit —amend</code> to replace already-published commits |
| 765 | (as in <a href="#fixing-a-mistake-by-rewriting-history" title="Fixing a mistake by rewriting history">the section called “Fixing a mistake by rewriting history”</a>), or |
| 766 | </li><li> |
| 767 | use <code class="literal">git rebase</code> to rebase any already-published commits (as |
| 768 | in <a href="#using-git-rebase" title="Keeping a patch series up to date using git-rebase">the section called “Keeping a patch series up to date using git-rebase”</a>). |
| 769 | </li></ul></div><p>You may force git-push to perform the update anyway by preceding the |
| 770 | branch name with a plus sign:</p><div class="literallayout"><p>$ git push ssh://yourserver.com/~you/proj.git +master</p></div><p>Normally whenever a branch head in a public repository is modified, it |
| Junio C Hamano | 878cc1e | 2007-12-14 08:35:13 | [diff] [blame] | 771 | is modified to point to a descendant of the commit that it pointed to |
| Junio C Hamano | ce3650e | 2007-11-26 04:20:11 | [diff] [blame] | 772 | before. By forcing a push in this situation, you break that convention. |
| 773 | (See <a href="#problems-with-rewriting-history" title="Problems with rewriting history">the section called “Problems with rewriting history”</a>.)</p><p>Nevertheless, this is a common practice for people that need a simple |
| 774 | way to publish a work-in-progress patch series, and it is an acceptable |
| 775 | compromise as long as you warn other developers that this is how you |
| 776 | intend to manage the branch.</p><p>It's also possible for a push to fail in this way when other people have |
| 777 | the right to push to the same repository. In that case, the correct |
| 778 | solution is to retry the push after first updating your work by either a |
| 779 | pull or a fetch followed by a rebase; see the |
| 780 | <a href="#setting-up-a-shared-repository" title="Setting up a shared repository">next section</a> and |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 781 | <a href="gitcvs-migration.html" target="_top">gitcvs-migration(7)</a> for more.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="setting-up-a-shared-repository"></a>Setting up a shared repository</h3></div></div></div><p>Another way to collaborate is by using a model similar to that |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 782 | commonly used in CVS, where several developers with special rights |
| 783 | all push to and pull from a single shared repository. See |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 784 | <a href="gitcvs-migration.html" target="_top">gitcvs-migration(7)</a> for instructions on how to |
| Junio C Hamano | ed7f4f6 | 2007-05-20 09:09:09 | [diff] [blame] | 785 | set this up.</p><p>However, while there is nothing wrong with git's support for shared |
| 786 | repositories, this mode of operation is not generally recommended, |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 787 | simply because the mode of collaboration that git supports—by |
| 788 | exchanging patches and pulling from public repositories—has so many |
| Junio C Hamano | ed7f4f6 | 2007-05-20 09:09:09 | [diff] [blame] | 789 | advantages over the central shared repository:</p><div class="itemizedlist"><ul type="disc"><li> |
| 790 | Git's ability to quickly import and merge patches allows a |
| 791 | single maintainer to process incoming changes even at very |
| 792 | high rates. And when that becomes too much, git-pull provides |
| 793 | an easy way for that maintainer to delegate this job to other |
| 794 | maintainers while still allowing optional review of incoming |
| 795 | changes. |
| 796 | </li><li> |
| 797 | Since every developer's repository has the same complete copy |
| 798 | of the project history, no repository is special, and it is |
| 799 | trivial for another developer to take over maintenance of a |
| 800 | project, either by mutual agreement, or because a maintainer |
| 801 | becomes unresponsive or difficult to work with. |
| 802 | </li><li> |
| 803 | The lack of a central group of "committers" means there is |
| 804 | less need for formal decisions about who is "in" and who is |
| 805 | "out". |
| 806 | </li></ul></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="setting-up-gitweb"></a>Allowing web browsing of a repository</h3></div></div></div><p>The gitweb cgi script provides users an easy way to browse your |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 807 | project's files and history without having to install git; see the file |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 808 | gitweb/INSTALL in the git source tree for instructions on setting it up.</p></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="sharing-development-examples"></a>Examples</h2></div></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="maintaining-topic-branches"></a>Maintaining topic branches for a Linux subsystem maintainer</h3></div></div></div><p>This describes how Tony Luck uses git in his role as maintainer of the |
| 809 | IA64 architecture for the Linux kernel.</p><p>He uses two public branches:</p><div class="itemizedlist"><ul type="disc"><li> |
| 810 | A "test" tree into which patches are initially placed so that they |
| 811 | can get some exposure when integrated with other ongoing development. |
| 812 | This tree is available to Andrew for pulling into -mm whenever he |
| 813 | wants. |
| 814 | </li><li> |
| 815 | A "release" tree into which tested patches are moved for final sanity |
| 816 | checking, and as a vehicle to send them upstream to Linus (by sending |
| 817 | him a "please pull" request.) |
| 818 | </li></ul></div><p>He also uses a set of temporary branches ("topic branches"), each |
| 819 | containing a logical grouping of patches.</p><p>To set this up, first create your work tree by cloning Linus's public |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 820 | tree:</p><div class="literallayout"><p>$ git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git work<br> |
| 821 | $ cd work</p></div><p>Linus's tree will be stored in the remote branch named origin/master, |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 822 | and can be updated using <a href="git-fetch.html" target="_top">git-fetch(1)</a>; you can track other |
| 823 | public trees using <a href="git-remote.html" target="_top">git-remote(1)</a> to set up a "remote" and |
| Junio C Hamano | 8b8b0f2 | 2007-08-26 22:10:26 | [diff] [blame] | 824 | <a href="git-fetch.html" target="_top">git-fetch(1)</a> to keep them up-to-date; see |
| 825 | <a href="#repositories-and-branches" title="Chapter 1. Repositories and Branches">Chapter 1, <i>Repositories and Branches</i></a>.</p><p>Now create the branches in which you are going to work; these start out |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 826 | at the current tip of origin/master branch, and should be set up (using |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 827 | the —track option to <a href="git-branch.html" target="_top">git-branch(1)</a>) to merge changes in from |
| 828 | Linus by default.</p><div class="literallayout"><p>$ git branch --track test origin/master<br> |
| Junio C Hamano | 764a667 | 2007-10-23 01:23:31 | [diff] [blame] | 829 | $ git branch --track release origin/master</p></div><p>These can be easily kept up to date using <a href="git-pull.html" target="_top">git-pull(1)</a>.</p><div class="literallayout"><p>$ git checkout test && git pull<br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 830 | $ git checkout release && git pull</p></div><p>Important note! If you have any local changes in these branches, then |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 831 | this merge will create a commit object in the history (with no local |
| 832 | changes git will simply do a "Fast forward" merge). Many people dislike |
| 833 | the "noise" that this creates in the Linux history, so you should avoid |
| 834 | doing this capriciously in the "release" branch, as these noisy commits |
| 835 | will become part of the permanent history when you ask Linus to pull |
| 836 | from the release branch.</p><p>A few configuration variables (see <a href="git-config.html" target="_top">git-config(1)</a>) can |
| 837 | make it easy to push both branches to your public tree. (See |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 838 | <a href="#setting-up-a-public-repository" title="Setting up a public repository">the section called “Setting up a public repository”</a>.)</p><div class="literallayout"><p>$ cat >> .git/config <<EOF<br> |
| 839 | [remote "mytree"]<br> |
| 840 | url = master.kernel.org:/pub/scm/linux/kernel/git/aegl/linux-2.6.git<br> |
| 841 | push = release<br> |
| 842 | push = test<br> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 843 | EOF</p></div><p>Then you can push both the test and release trees using |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 844 | <a href="git-push.html" target="_top">git-push(1)</a>:</p><div class="literallayout"><p>$ git push mytree</p></div><p>or push just one of the test and release branches using:</p><div class="literallayout"><p>$ git push mytree test</p></div><p>or</p><div class="literallayout"><p>$ git push mytree release</p></div><p>Now to apply some patches from the community. Think of a short |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 845 | snappy name for a branch to hold this patch (or related group of |
| 846 | patches), and create a new branch from the current tip of Linus's |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 847 | branch:</p><div class="literallayout"><p>$ git checkout -b speed-up-spinlocks origin</p></div><p>Now you apply the patch(es), run some tests, and commit the change(s). If |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 848 | the patch is a multi-part series, then you should apply each as a separate |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 849 | commit to this branch.</p><div class="literallayout"><p>$ ... patch ... test ... commit [ ... patch ... test ... commit ]*</p></div><p>When you are happy with the state of this change, you can pull it into the |
| 850 | "test" branch in preparation to make it public:</p><div class="literallayout"><p>$ git checkout test && git pull . speed-up-spinlocks</p></div><p>It is unlikely that you would have any conflicts here … but you might if you |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 851 | spent a while on this step and had also pulled new versions from upstream.</p><p>Some time later when enough time has passed and testing done, you can pull the |
| 852 | same branch into the "release" tree ready to go upstream. This is where you |
| 853 | see the value of keeping each patch (or patch series) in its own branch. It |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 854 | means that the patches can be moved into the "release" tree in any order.</p><div class="literallayout"><p>$ git checkout release && git pull . speed-up-spinlocks</p></div><p>After a while, you will have a number of branches, and despite the |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 855 | well chosen names you picked for each of them, you may forget what |
| 856 | they are for, or what status they are in. To get a reminder of what |
| Junio C Hamano | 764a667 | 2007-10-23 01:23:31 | [diff] [blame] | 857 | changes are in a specific branch, use:</p><div class="literallayout"><p>$ git log linux..branchname | git-shortlog</p></div><p>To see whether it has already been merged into the test or release branches, |
| 858 | use:</p><div class="literallayout"><p>$ git log test..branchname</p></div><p>or</p><div class="literallayout"><p>$ git log release..branchname</p></div><p>(If this branch has not yet been merged, you will see some log entries. |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 859 | If it has been merged, then there will be no output.)</p><p>Once a patch completes the great cycle (moving from test to release, |
| 860 | then pulled by Linus, and finally coming back into your local |
| Junio C Hamano | 764a667 | 2007-10-23 01:23:31 | [diff] [blame] | 861 | "origin/master" branch), the branch for this change is no longer needed. |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 862 | You detect this when the output from:</p><div class="literallayout"><p>$ git log origin..branchname</p></div><p>is empty. At this point the branch can be deleted:</p><div class="literallayout"><p>$ git branch -d branchname</p></div><p>Some changes are so trivial that it is not necessary to create a separate |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 863 | branch and then merge into each of the test and release branches. For |
| 864 | these changes, just apply directly to the "release" branch, and then |
| 865 | merge that into the "test" branch.</p><p>To create diffstat and shortlog summaries of changes to include in a "please |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 866 | pull" request to Linus you can use:</p><div class="literallayout"><p>$ git diff --stat origin..release</p></div><p>and</p><div class="literallayout"><p>$ git log -p origin..release | git shortlog</p></div><p>Here are some of the scripts that simplify all this even further.</p><div class="literallayout"><p>==== update script ====<br> |
| 867 | # Update a branch in my GIT tree. If the branch to be updated<br> |
| 868 | # is origin, then pull from kernel.org. Otherwise merge<br> |
| 869 | # origin/master branch into test|release branch<br> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 870 | <br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 871 | case "$1" in<br> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 872 | test|release)<br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 873 | git checkout $1 && git pull . origin<br> |
| 874 | ;;<br> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 875 | origin)<br> |
| Junio C Hamano | 9810d63 | 2007-09-24 01:05:34 | [diff] [blame] | 876 | before=$(git rev-parse refs/remotes/origin/master)<br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 877 | git fetch origin<br> |
| Junio C Hamano | 9810d63 | 2007-09-24 01:05:34 | [diff] [blame] | 878 | after=$(git rev-parse refs/remotes/origin/master)<br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 879 | if [ $before != $after ]<br> |
| 880 | then<br> |
| 881 | git log $before..$after | git shortlog<br> |
| 882 | fi<br> |
| 883 | ;;<br> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 884 | *)<br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 885 | echo "Usage: $0 origin|test|release" 1>&2<br> |
| 886 | exit 1<br> |
| 887 | ;;<br> |
| 888 | esac</p></div><div class="literallayout"><p>==== merge script ====<br> |
| 889 | # Merge a branch into either the test or release branch<br> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 890 | <br> |
| 891 | pname=$0<br> |
| 892 | <br> |
| 893 | usage()<br> |
| 894 | {<br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 895 | echo "Usage: $pname branch test|release" 1>&2<br> |
| 896 | exit 1<br> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 897 | }<br> |
| 898 | <br> |
| Junio C Hamano | 9810d63 | 2007-09-24 01:05:34 | [diff] [blame] | 899 | git show-ref -q --verify -- refs/heads/"$1" || {<br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 900 | echo "Can't see branch <$1>" 1>&2<br> |
| 901 | usage<br> |
| Junio C Hamano | 9810d63 | 2007-09-24 01:05:34 | [diff] [blame] | 902 | }<br> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 903 | <br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 904 | case "$2" in<br> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 905 | test|release)<br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 906 | if [ $(git log $2..$1 | wc -c) -eq 0 ]<br> |
| 907 | then<br> |
| 908 | echo $1 already merged into $2 1>&2<br> |
| 909 | exit 1<br> |
| 910 | fi<br> |
| 911 | git checkout $2 && git pull . $1<br> |
| 912 | ;;<br> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 913 | *)<br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 914 | usage<br> |
| 915 | ;;<br> |
| 916 | esac</p></div><div class="literallayout"><p>==== status script ====<br> |
| 917 | # report on status of my ia64 GIT tree<br> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 918 | <br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 919 | gb=$(tput setab 2)<br> |
| 920 | rb=$(tput setab 1)<br> |
| 921 | restore=$(tput setab 9)<br> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 922 | <br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 923 | if [ `git rev-list test..release | wc -c` -gt 0 ]<br> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 924 | then<br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 925 | echo $rb Warning: commits in release that are not in test $restore<br> |
| 926 | git log test..release<br> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 927 | fi<br> |
| 928 | <br> |
| Junio C Hamano | 9810d63 | 2007-09-24 01:05:34 | [diff] [blame] | 929 | for branch in `git show-ref --heads | sed 's|^.*/||'`<br> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 930 | do<br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 931 | if [ $branch = test -o $branch = release ]<br> |
| 932 | then<br> |
| 933 | continue<br> |
| 934 | fi<br> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 935 | <br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 936 | echo -n $gb ======= $branch ====== $restore " "<br> |
| 937 | status=<br> |
| 938 | for ref in test release origin/master<br> |
| 939 | do<br> |
| 940 | if [ `git rev-list $ref..$branch | wc -c` -gt 0 ]<br> |
| 941 | then<br> |
| 942 | status=$status${ref:0:1}<br> |
| 943 | fi<br> |
| 944 | done<br> |
| 945 | case $status in<br> |
| 946 | trl)<br> |
| 947 | echo $rb Need to pull into test $restore<br> |
| 948 | ;;<br> |
| 949 | rl)<br> |
| 950 | echo "In test"<br> |
| 951 | ;;<br> |
| 952 | l)<br> |
| 953 | echo "Waiting for linus"<br> |
| 954 | ;;<br> |
| 955 | "")<br> |
| 956 | echo $rb All done $restore<br> |
| 957 | ;;<br> |
| 958 | *)<br> |
| 959 | echo $rb "<$status>" $restore<br> |
| 960 | ;;<br> |
| 961 | esac<br> |
| 962 | git log origin/master..$branch | git shortlog<br> |
| Junio C Hamano | ce3650e | 2007-11-26 04:20:11 | [diff] [blame] | 963 | done</p></div></div></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="cleaning-up-history"></a>Chapter 5. Rewriting history and maintaining patch series</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="section"><a href="#patch-series">Creating the perfect patch series</a></span></dt><dt><span class="section"><a href="#using-git-rebase">Keeping a patch series up to date using git-rebase</a></span></dt><dt><span class="section"><a href="#rewriting-one-commit">Rewriting a single commit</a></span></dt><dt><span class="section"><a href="#reordering-patch-series">Reordering or selecting from a patch series</a></span></dt><dt><span class="section"><a href="#patch-series-tools">Other tools</a></span></dt><dt><span class="section"><a href="#problems-with-rewriting-history">Problems with rewriting history</a></span></dt><dt><span class="section"><a href="#bisect-merges">Why bisecting merge commits can be harder than bisecting linear history</a></span></dt></dl></div><p>Normally commits are only added to a project, never taken away or |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 964 | replaced. Git is designed with this assumption, and violating it will |
| 965 | cause git's merge machinery (for example) to do the wrong thing.</p><p>However, there is a situation in which it can be useful to violate this |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 966 | assumption.</p><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="patch-series"></a>Creating the perfect patch series</h2></div></div></div><p>Suppose you are a contributor to a large project, and you want to add a |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 967 | complicated feature, and to present it to the other developers in a way |
| 968 | that makes it easy for them to read your changes, verify that they are |
| 969 | correct, and understand why you made each change.</p><p>If you present all of your changes as a single patch (or commit), they |
| Junio C Hamano | db911ee | 2007-02-28 08:13:52 | [diff] [blame] | 970 | may find that it is too much to digest all at once.</p><p>If you present them with the entire history of your work, complete with |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 971 | mistakes, corrections, and dead ends, they may be overwhelmed.</p><p>So the ideal is usually to produce a series of patches such that:</p><div class="orderedlist"><ol type="1"><li> |
| 972 | Each patch can be applied in order. |
| 973 | </li><li> |
| 974 | Each patch includes a single logical change, together with a |
| 975 | message explaining the change. |
| 976 | </li><li> |
| 977 | No patch introduces a regression: after applying any initial |
| 978 | part of the series, the resulting project still compiles and |
| 979 | works, and has no bugs that it didn't have before. |
| 980 | </li><li> |
| 981 | The complete series produces the same end result as your own |
| 982 | (probably much messier!) development process did. |
| 983 | </li></ol></div><p>We will introduce some tools that can help you do this, explain how to |
| 984 | use them, and then explain some of the problems that can arise because |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 985 | you are rewriting history.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="using-git-rebase"></a>Keeping a patch series up to date using git-rebase</h2></div></div></div><p>Suppose that you create a branch "mywork" on a remote-tracking branch |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 986 | "origin", and create some commits on top of it:</p><div class="literallayout"><p>$ git checkout -b mywork origin<br> |
| 987 | $ vi file.txt<br> |
| 988 | $ git commit<br> |
| 989 | $ vi otherfile.txt<br> |
| 990 | $ git commit<br> |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 991 | ...</p></div><p>You have performed no merges into mywork, so it is just a simple linear |
| Junio C Hamano | c51fede | 2007-03-12 07:29:20 | [diff] [blame] | 992 | sequence of patches on top of "origin":</p><pre class="literallayout"> o--o--o <-- origin |
| 993 | \ |
| 994 | o--o--o <-- mywork</pre><p>Some more interesting work has been done in the upstream project, and |
| 995 | "origin" has advanced:</p><pre class="literallayout"> o--o--O--o--o--o <-- origin |
| 996 | \ |
| 997 | a--b--c <-- mywork</pre><p>At this point, you could use "pull" to merge your changes back in; |
| 998 | the result would create a new merge commit, like this:</p><pre class="literallayout"> o--o--O--o--o--o <-- origin |
| 999 | \ \ |
| 1000 | a--b--c--m <-- mywork</pre><p>However, if you prefer to keep the history in mywork a simple series of |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1001 | commits without any merges, you may instead choose to use |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 1002 | <a href="git-rebase.html" target="_top">git-rebase(1)</a>:</p><div class="literallayout"><p>$ git checkout mywork<br> |
| 1003 | $ git rebase origin</p></div><p>This will remove each of your commits from mywork, temporarily saving |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1004 | them as patches (in a directory named ".dotest"), update mywork to |
| 1005 | point at the latest version of origin, then apply each of the saved |
| Junio C Hamano | c51fede | 2007-03-12 07:29:20 | [diff] [blame] | 1006 | patches to the new mywork. The result will look like:</p><pre class="literallayout"> o--o--O--o--o--o <-- origin |
| 1007 | \ |
| 1008 | a'--b'--c' <-- mywork</pre><p>In the process, it may discover conflicts. In that case it will stop |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1009 | and allow you to fix the conflicts; after fixing conflicts, use "git |
| 1010 | add" to update the index with those contents, and then, instead of |
| Junio C Hamano | 764a667 | 2007-10-23 01:23:31 | [diff] [blame] | 1011 | running git-commit, just run</p><div class="literallayout"><p>$ git rebase --continue</p></div><p>and git will continue applying the rest of the patches.</p><p>At any point you may use the <code class="literal">—abort</code> option to abort this process and |
| Junio C Hamano | ce3650e | 2007-11-26 04:20:11 | [diff] [blame] | 1012 | return mywork to the state it had before you started the rebase:</p><div class="literallayout"><p>$ git rebase --abort</p></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="rewriting-one-commit"></a>Rewriting a single commit</h2></div></div></div><p>We saw in <a href="#fixing-a-mistake-by-rewriting-history" title="Fixing a mistake by rewriting history">the section called “Fixing a mistake by rewriting history”</a> that you can replace the |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 1013 | most recent commit using</p><div class="literallayout"><p>$ git commit --amend</p></div><p>which will replace the old commit by a new commit incorporating your |
| Junio C Hamano | ce3650e | 2007-11-26 04:20:11 | [diff] [blame] | 1014 | changes, giving you a chance to edit the old commit message first.</p><p>You can also use a combination of this and <a href="git-rebase.html" target="_top">git-rebase(1)</a> to |
| 1015 | replace a commit further back in your history and recreate the |
| 1016 | intervening changes on top of it. First, tag the problematic commit |
| 1017 | with</p><div class="literallayout"><p>$ git tag bad mywork~5</p></div><p>(Either gitk or git-log may be useful for finding the commit.)</p><p>Then check out that commit, edit it, and rebase the rest of the series |
| Junio C Hamano | 0e3cb53 | 2007-04-17 08:28:11 | [diff] [blame] | 1018 | on top of it (note that we could check out the commit on a temporary |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 1019 | branch, but instead we're using a <a href="#detached-head" title="Examining an old version without creating a new branch">detached head</a>):</p><div class="literallayout"><p>$ git checkout bad<br> |
| 1020 | $ # make changes here and update the index<br> |
| 1021 | $ git commit --amend<br> |
| 1022 | $ git rebase --onto HEAD bad mywork</p></div><p>When you're done, you'll be left with mywork checked out, with the top |
| Junio C Hamano | 0e3cb53 | 2007-04-17 08:28:11 | [diff] [blame] | 1023 | patches on mywork reapplied on top of your modified commit. You can |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 1024 | then clean up with</p><div class="literallayout"><p>$ git tag -d bad</p></div><p>Note that the immutable nature of git history means that you haven't really |
| Junio C Hamano | aa83a7d | 2007-03-05 02:37:29 | [diff] [blame] | 1025 | "modified" existing commits; instead, you have replaced the old commits with |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 1026 | new commits having new object names.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="reordering-patch-series"></a>Reordering or selecting from a patch series</h2></div></div></div><p>Given one existing commit, the <a href="git-cherry-pick.html" target="_top">git-cherry-pick(1)</a> command |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1027 | allows you to apply the change introduced by that commit and create a |
| 1028 | new commit that records it. So, for example, if "mywork" points to a |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 1029 | series of patches on top of "origin", you might do something like:</p><div class="literallayout"><p>$ git checkout -b mywork-new origin<br> |
| Junio C Hamano | 764a667 | 2007-10-23 01:23:31 | [diff] [blame] | 1030 | $ gitk origin..mywork &</p></div><p>and browse through the list of patches in the mywork branch using gitk, |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1031 | applying them (possibly in a different order) to mywork-new using |
| Junio C Hamano | 764a667 | 2007-10-23 01:23:31 | [diff] [blame] | 1032 | cherry-pick, and possibly modifying them as you go using <code class="literal">commit —amend</code>. |
| Junio C Hamano | 8b8b0f2 | 2007-08-26 22:10:26 | [diff] [blame] | 1033 | The <a href="git-gui.html" target="_top">git-gui(1)</a> command may also help as it allows you to |
| 1034 | individually select diff hunks for inclusion in the index (by |
| 1035 | right-clicking on the diff hunk and choosing "Stage Hunk for Commit").</p><p>Another technique is to use git-format-patch to create a series of |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 1036 | patches, then reset the state to before the patches:</p><div class="literallayout"><p>$ git format-patch origin<br> |
| 1037 | $ git reset --hard origin</p></div><p>Then modify, reorder, or eliminate patches as preferred before applying |
| Junio C Hamano | a638742 | 2007-08-25 03:54:27 | [diff] [blame] | 1038 | them again with <a href="git-am.html" target="_top">git-am(1)</a>.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="patch-series-tools"></a>Other tools</h2></div></div></div><p>There are numerous other tools, such as StGIT, which exist for the |
| Junio C Hamano | db911ee | 2007-02-28 08:13:52 | [diff] [blame] | 1039 | purpose of maintaining a patch series. These are outside of the scope of |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 1040 | this manual.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="problems-with-rewriting-history"></a>Problems with rewriting history</h2></div></div></div><p>The primary problem with rewriting the history of a branch has to do |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1041 | with merging. Suppose somebody fetches your branch and merges it into |
| Junio C Hamano | c51fede | 2007-03-12 07:29:20 | [diff] [blame] | 1042 | their branch, with a result something like this:</p><pre class="literallayout"> o--o--O--o--o--o <-- origin |
| 1043 | \ \ |
| 1044 | t--t--t--m <-- their branch:</pre><p>Then suppose you modify the last three commits:</p><pre class="literallayout"> o--o--o <-- new head of origin |
| 1045 | / |
| 1046 | o--o--O--o--o--o <-- old head of origin</pre><p>If we examined all this history together in one repository, it will |
| 1047 | look like:</p><pre class="literallayout"> o--o--o <-- new head of origin |
| 1048 | / |
| 1049 | o--o--O--o--o--o <-- old head of origin |
| 1050 | \ \ |
| 1051 | t--t--t--m <-- their branch:</pre><p>Git has no way of knowing that the new head is an updated version of |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1052 | the old head; it treats this situation exactly the same as it would if |
| 1053 | two developers had independently done the work on the old and new heads |
| 1054 | in parallel. At this point, if someone attempts to merge the new head |
| 1055 | in to their branch, git will attempt to merge together the two (old and |
| 1056 | new) lines of development, instead of trying to replace the old by the |
| 1057 | new. The results are likely to be unexpected.</p><p>You may still choose to publish branches whose history is rewritten, |
| 1058 | and it may be useful for others to be able to fetch those branches in |
| 1059 | order to examine or test them, but they should not attempt to pull such |
| 1060 | branches into their own work.</p><p>For true distributed development that supports proper merging, |
| Junio C Hamano | 393e57f | 2007-11-20 04:53:25 | [diff] [blame] | 1061 | published branches should never be rewritten.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="bisect-merges"></a>Why bisecting merge commits can be harder than bisecting linear history</h2></div></div></div><p>The <a href="git-bisect.html" target="_top">git-bisect(1)</a> command correctly handles history that |
| 1062 | includes merge commits. However, when the commit that it finds is a |
| 1063 | merge commit, the user may need to work harder than usual to figure out |
| 1064 | why that commit introduced a problem.</p><p>Imagine this history:</p><pre class="literallayout"> ---Z---o---X---...---o---A---C---D |
| 1065 | \ / |
| 1066 | o---o---Y---...---o---B</pre><p>Suppose that on the upper line of development, the meaning of one |
| 1067 | of the functions that exists at Z is changed at commit X. The |
| 1068 | commits from Z leading to A change both the function's |
| 1069 | implementation and all calling sites that exist at Z, as well |
| 1070 | as new calling sites they add, to be consistent. There is no |
| 1071 | bug at A.</p><p>Suppose that in the meantime on the lower line of development somebody |
| 1072 | adds a new calling site for that function at commit Y. The |
| 1073 | commits from Z leading to B all assume the old semantics of that |
| 1074 | function and the callers and the callee are consistent with each |
| 1075 | other. There is no bug at B, either.</p><p>Suppose further that the two development lines merge cleanly at C, |
| 1076 | so no conflict resolution is required.</p><p>Nevertheless, the code at C is broken, because the callers added |
| 1077 | on the lower line of development have not been converted to the new |
| 1078 | semantics introduced on the upper line of development. So if all |
| 1079 | you know is that D is bad, that Z is good, and that |
| 1080 | <a href="git-bisect.html" target="_top">git-bisect(1)</a> identifies C as the culprit, how will you |
| 1081 | figure out that the problem is due to this change in semantics?</p><p>When the result of a git-bisect is a non-merge commit, you should |
| 1082 | normally be able to discover the problem by examining just that commit. |
| 1083 | Developers can make this easy by breaking their changes into small |
| 1084 | self-contained commits. That won't help in the case above, however, |
| 1085 | because the problem isn't obvious from examination of any single |
| 1086 | commit; instead, a global view of the development is required. To |
| 1087 | make matters worse, the change in semantics in the problematic |
| 1088 | function may be just one small part of the changes in the upper |
| 1089 | line of development.</p><p>On the other hand, if instead of merging at C you had rebased the |
| 1090 | history between Z to B on top of A, you would have gotten this |
| 1091 | linear history:</p><pre class="literallayout"> ---Z---o---X--...---o---A---o---o---Y*--...---o---B*--D*</pre><p>Bisecting between Z and D* would hit a single culprit commit Y*, |
| 1092 | and understanding why Y* was broken would probably be easier.</p><p>Partly for this reason, many experienced git users, even when |
| 1093 | working on an otherwise merge-heavy project, keep the history |
| 1094 | linear by rebasing against the latest upstream version before |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 1095 | publishing.</p></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="advanced-branch-management"></a>Chapter 6. Advanced branch management</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="section"><a href="#fetching-individual-branches">Fetching individual branches</a></span></dt><dt><span class="section"><a href="#fetch-fast-forwards">git fetch and fast-forwards</a></span></dt><dt><span class="section"><a href="#forcing-fetch">Forcing git-fetch to do non-fast-forward updates</a></span></dt><dt><span class="section"><a href="#remote-branch-configuration">Configuring remote branches</a></span></dt></dl></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="fetching-individual-branches"></a>Fetching individual branches</h2></div></div></div><p>Instead of using <a href="git-remote.html" target="_top">git-remote(1)</a>, you can also choose just |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1096 | to update one branch at a time, and to store it locally under an |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 1097 | arbitrary name:</p><div class="literallayout"><p>$ git fetch origin todo:my-todo-work</p></div><p>The first argument, "origin", just tells git to fetch from the |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1098 | repository you originally cloned from. The second argument tells git |
| 1099 | to fetch the branch named "todo" from the remote repository, and to |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 1100 | store it locally under the name refs/heads/my-todo-work.</p><p>You can also fetch branches from other repositories; so</p><div class="literallayout"><p>$ git fetch git://example.com/proj.git master:example-master</p></div><p>will create a new branch named "example-master" and store in it the |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1101 | branch named "master" from the repository at the given URL. If you |
| 1102 | already have a branch named example-master, it will attempt to |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 1103 | <a href="#fast-forwards" title="Fast-forward merges">fast-forward</a> to the commit given by example.com's |
| 1104 | master branch. In more detail:</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="fetch-fast-forwards"></a>git fetch and fast-forwards</h2></div></div></div><p>In the previous example, when updating an existing branch, "git |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1105 | fetch" checks to make sure that the most recent commit on the remote |
| 1106 | branch is a descendant of the most recent commit on your copy of the |
| 1107 | branch before updating your copy of the branch to point at the new |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 1108 | commit. Git calls this process a <a href="#fast-forwards" title="Fast-forward merges">fast forward</a>.</p><p>A fast forward looks something like this:</p><pre class="literallayout"> o--o--o--o <-- old head of the branch |
| Junio C Hamano | c51fede | 2007-03-12 07:29:20 | [diff] [blame] | 1109 | \ |
| 1110 | o--o--o <-- new head of the branch</pre><p>In some cases it is possible that the new head will <span class="strong"><strong>not</strong></span> actually be |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1111 | a descendant of the old head. For example, the developer may have |
| 1112 | realized she made a serious mistake, and decided to backtrack, |
| Junio C Hamano | c51fede | 2007-03-12 07:29:20 | [diff] [blame] | 1113 | resulting in a situation like:</p><pre class="literallayout"> o--o--o--o--a--b <-- old head of the branch |
| 1114 | \ |
| 1115 | o--o--o <-- new head of the branch</pre><p>In this case, "git fetch" will fail, and print out a warning.</p><p>In that case, you can still force git to update to the new head, as |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1116 | described in the following section. However, note that in the |
| 1117 | situation above this may mean losing the commits labeled "a" and "b", |
| 1118 | unless you've already created a reference of your own pointing to |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 1119 | them.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="forcing-fetch"></a>Forcing git-fetch to do non-fast-forward updates</h2></div></div></div><p>If git fetch fails because the new head of a branch is not a |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 1120 | descendant of the old head, you may force the update with:</p><div class="literallayout"><p>$ git fetch git://example.com/proj.git +master:refs/remotes/example/master</p></div><p>Note the addition of the "+" sign. Alternatively, you can use the "-f" |
| 1121 | flag to force updates of all the fetched branches, as in:</p><div class="literallayout"><p>$ git fetch -f origin</p></div><p>Be aware that commits that the old version of example/master pointed at |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 1122 | may be lost, as we saw in the previous section.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="remote-branch-configuration"></a>Configuring remote branches</h2></div></div></div><p>We saw above that "origin" is just a shortcut to refer to the |
| Junio C Hamano | db911ee | 2007-02-28 08:13:52 | [diff] [blame] | 1123 | repository that you originally cloned from. This information is |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1124 | stored in git configuration variables, which you can see using |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 1125 | <a href="git-config.html" target="_top">git-config(1)</a>:</p><div class="literallayout"><p>$ git config -l<br> |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1126 | core.repositoryformatversion=0<br> |
| 1127 | core.filemode=true<br> |
| 1128 | core.logallrefupdates=true<br> |
| 1129 | remote.origin.url=git://git.kernel.org/pub/scm/git/git.git<br> |
| 1130 | remote.origin.fetch=+refs/heads/*:refs/remotes/origin/*<br> |
| 1131 | branch.master.remote=origin<br> |
| 1132 | branch.master.merge=refs/heads/master</p></div><p>If there are other repositories that you also use frequently, you can |
| 1133 | create similar configuration options to save typing; for example, |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 1134 | after</p><div class="literallayout"><p>$ git config remote.example.url git://example.com/proj.git</p></div><p>then the following two commands will do the same thing:</p><div class="literallayout"><p>$ git fetch git://example.com/proj.git master:refs/remotes/example/master<br> |
| 1135 | $ git fetch example master:refs/remotes/example/master</p></div><p>Even better, if you add one more option:</p><div class="literallayout"><p>$ git config remote.example.fetch master:refs/remotes/example/master</p></div><p>then the following commands will all do the same thing:</p><div class="literallayout"><p>$ git fetch git://example.com/proj.git master:refs/remotes/example/master<br> |
| 1136 | $ git fetch example master:refs/remotes/example/master<br> |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 1137 | $ git fetch example</p></div><p>You can also add a "+" to force the update each time:</p><div class="literallayout"><p>$ git config remote.example.fetch +master:ref/remotes/example/master</p></div><p>Don't do this unless you're sure you won't mind "git-fetch" possibly |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1138 | throwing away commits on mybranch.</p><p>Also note that all of the above configuration can be performed by |
| 1139 | directly editing the file .git/config instead of using |
| 1140 | <a href="git-config.html" target="_top">git-config(1)</a>.</p><p>See <a href="git-config.html" target="_top">git-config(1)</a> for more details on the configuration |
| Junio C Hamano | ce3650e | 2007-11-26 04:20:11 | [diff] [blame] | 1141 | options mentioned above.</p></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="git-concepts"></a>Chapter 7. Git concepts</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="section"><a href="#the-object-database">The Object Database</a></span></dt><dd><dl><dt><span class="section"><a href="#commit-object">Commit Object</a></span></dt><dt><span class="section"><a href="#tree-object">Tree Object</a></span></dt><dt><span class="section"><a href="#blob-object">Blob Object</a></span></dt><dt><span class="section"><a href="#trust">Trust</a></span></dt><dt><span class="section"><a href="#tag-object">Tag Object</a></span></dt><dt><span class="section"><a href="#pack-files">How git stores objects efficiently: pack files</a></span></dt><dt><span class="section"><a href="#dangling-objects">Dangling objects</a></span></dt><dt><span class="section"><a href="#recovering-from-repository-corruption">Recovering from repository corruption</a></span></dt></dl></dd><dt><span class="section"><a href="#the-index">The index</a></span></dt></dl></div><p>Git is built on a small number of simple but powerful ideas. While it |
| Junio C Hamano | 597ffcf | 2007-09-17 17:33:15 | [diff] [blame] | 1142 | is possible to get things done without understanding them, you will find |
| 1143 | git much more intuitive if you do.</p><p>We start with the most important, the <a href="#def_object_database">object database</a> and the <a href="#def_index">index</a>.</p><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="the-object-database"></a>The Object Database</h2></div></div></div><p>We already saw in <a href="#understanding-commits" title="Understanding History: Commits">the section called “Understanding History: Commits”</a> that all commits are stored |
| 1144 | under a 40-digit "object name". In fact, all the information needed to |
| 1145 | represent the history of a project is stored in objects with such names. |
| 1146 | In each case the name is calculated by taking the SHA1 hash of the |
| 1147 | contents of the object. The SHA1 hash is a cryptographic hash function. |
| 1148 | What that means to us is that it is impossible to find two different |
| 1149 | objects with the same name. This has a number of advantages; among |
| 1150 | others:</p><div class="itemizedlist"><ul type="disc"><li> |
| 1151 | Git can quickly determine whether two objects are identical or not, |
| 1152 | just by comparing names. |
| 1153 | </li><li> |
| Junio C Hamano | 764a667 | 2007-10-23 01:23:31 | [diff] [blame] | 1154 | Since object names are computed the same way in every repository, the |
| Junio C Hamano | 597ffcf | 2007-09-17 17:33:15 | [diff] [blame] | 1155 | same content stored in two repositories will always be stored under |
| 1156 | the same name. |
| 1157 | </li><li> |
| 1158 | Git can detect errors when it reads an object, by checking that the |
| 1159 | object's name is still the SHA1 hash of its contents. |
| 1160 | </li></ul></div><p>(See <a href="#object-details" title="Object storage format">the section called “Object storage format”</a> for the details of the object formatting and |
| 1161 | SHA1 calculation.)</p><p>There are four different types of objects: "blob", "tree", "commit", and |
| 1162 | "tag".</p><div class="itemizedlist"><ul type="disc"><li> |
| 1163 | A <a href="#def_blob_object">"blob" object</a> is used to store file data. |
| 1164 | </li><li> |
| 1165 | A <a href="#def_tree_object">"tree" object</a> is an object that ties one or more |
| 1166 | "blob" objects into a directory structure. In addition, a tree object |
| 1167 | can refer to other tree objects, thus creating a directory hierarchy. |
| 1168 | </li><li> |
| 1169 | A <a href="#def_commit_object">"commit" object</a> ties such directory hierarchies |
| Junio C Hamano | 764a667 | 2007-10-23 01:23:31 | [diff] [blame] | 1170 | together into a <a href="#def_DAG">directed acyclic graph</a> of revisions—each |
| Junio C Hamano | 597ffcf | 2007-09-17 17:33:15 | [diff] [blame] | 1171 | commit contains the object name of exactly one tree designating the |
| 1172 | directory hierarchy at the time of the commit. In addition, a commit |
| 1173 | refers to "parent" commit objects that describe the history of how we |
| 1174 | arrived at that directory hierarchy. |
| 1175 | </li><li> |
| 1176 | A <a href="#def_tag_object">"tag" object</a> symbolically identifies and can be |
| 1177 | used to sign other objects. It contains the object name and type of |
| 1178 | another object, a symbolic name (of course!) and, optionally, a |
| 1179 | signature. |
| 1180 | </li></ul></div><p>The object types in some more detail:</p><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="commit-object"></a>Commit Object</h3></div></div></div><p>The "commit" object links a physical state of a tree with a description |
| 1181 | of how we got there and why. Use the —pretty=raw option to |
| 1182 | <a href="git-show.html" target="_top">git-show(1)</a> or <a href="git-log.html" target="_top">git-log(1)</a> to examine your favorite |
| 1183 | commit:</p><div class="literallayout"><p>$ git show -s --pretty=raw 2be7fcb476<br> |
| 1184 | commit 2be7fcb4764f2dbcee52635b91fedb1b3dcf7ab4<br> |
| 1185 | tree fb3a8bdd0ceddd019615af4d57a53f43d8cee2bf<br> |
| 1186 | parent 257a84d9d02e90447b149af58b271c19405edb6a<br> |
| 1187 | author Dave Watson <dwatson@mimvista.com> 1187576872 -0400<br> |
| 1188 | committer Junio C Hamano <gitster@pobox.com> 1187591163 -0700<br> |
| 1189 | <br> |
| 1190 | Fix misspelling of 'suppress' in docs<br> |
| 1191 | <br> |
| 1192 | Signed-off-by: Junio C Hamano <gitster@pobox.com></p></div><p>As you can see, a commit is defined by:</p><div class="itemizedlist"><ul type="disc"><li> |
| 1193 | a tree: The SHA1 name of a tree object (as defined below), representing |
| 1194 | the contents of a directory at a certain point in time. |
| 1195 | </li><li> |
| 1196 | parent(s): The SHA1 name of some number of commits which represent the |
| Junio C Hamano | 878cc1e | 2007-12-14 08:35:13 | [diff] [blame] | 1197 | immediately previous step(s) in the history of the project. The |
| Junio C Hamano | 597ffcf | 2007-09-17 17:33:15 | [diff] [blame] | 1198 | example above has one parent; merge commits may have more than |
| 1199 | one. A commit with no parents is called a "root" commit, and |
| 1200 | represents the initial revision of a project. Each project must have |
| 1201 | at least one root. A project can also have multiple roots, though |
| 1202 | that isn't common (or necessarily a good idea). |
| 1203 | </li><li> |
| 1204 | an author: The name of the person responsible for this change, together |
| 1205 | with its date. |
| 1206 | </li><li> |
| 1207 | a committer: The name of the person who actually created the commit, |
| 1208 | with the date it was done. This may be different from the author, for |
| 1209 | example, if the author was someone who wrote a patch and emailed it |
| 1210 | to the person who used it to create the commit. |
| 1211 | </li><li> |
| 1212 | a comment describing this commit. |
| 1213 | </li></ul></div><p>Note that a commit does not itself contain any information about what |
| 1214 | actually changed; all changes are calculated by comparing the contents |
| 1215 | of the tree referred to by this commit with the trees associated with |
| 1216 | its parents. In particular, git does not attempt to record file renames |
| 1217 | explicitly, though it can identify cases where the existence of the same |
| 1218 | file data at changing paths suggests a rename. (See, for example, the |
| 1219 | -M option to <a href="git-diff.html" target="_top">git-diff(1)</a>).</p><p>A commit is usually created by <a href="git-commit.html" target="_top">git-commit(1)</a>, which creates a |
| 1220 | commit whose parent is normally the current HEAD, and whose tree is |
| 1221 | taken from the content currently stored in the index.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="tree-object"></a>Tree Object</h3></div></div></div><p>The ever-versatile <a href="git-show.html" target="_top">git-show(1)</a> command can also be used to |
| 1222 | examine tree objects, but <a href="git-ls-tree.html" target="_top">git-ls-tree(1)</a> will give you more |
| 1223 | details:</p><div class="literallayout"><p>$ git ls-tree fb3a8bdd0ce<br> |
| 1224 | 100644 blob 63c918c667fa005ff12ad89437f2fdc80926e21c .gitignore<br> |
| 1225 | 100644 blob 5529b198e8d14decbe4ad99db3f7fb632de0439d .mailmap<br> |
| 1226 | 100644 blob 6ff87c4664981e4397625791c8ea3bbb5f2279a3 COPYING<br> |
| 1227 | 040000 tree 2fb783e477100ce076f6bf57e4a6f026013dc745 Documentation<br> |
| 1228 | 100755 blob 3c0032cec592a765692234f1cba47dfdcc3a9200 GIT-VERSION-GEN<br> |
| 1229 | 100644 blob 289b046a443c0647624607d471289b2c7dcd470b INSTALL<br> |
| 1230 | 100644 blob 4eb463797adc693dc168b926b6932ff53f17d0b1 Makefile<br> |
| 1231 | 100644 blob 548142c327a6790ff8821d67c2ee1eff7a656b52 README<br> |
| 1232 | ...</p></div><p>As you can see, a tree object contains a list of entries, each with a |
| 1233 | mode, object type, SHA1 name, and name, sorted by name. It represents |
| 1234 | the contents of a single directory tree.</p><p>The object type may be a blob, representing the contents of a file, or |
| 1235 | another tree, representing the contents of a subdirectory. Since trees |
| 1236 | and blobs, like all other objects, are named by the SHA1 hash of their |
| 1237 | contents, two trees have the same SHA1 name if and only if their |
| 1238 | contents (including, recursively, the contents of all subdirectories) |
| 1239 | are identical. This allows git to quickly determine the differences |
| 1240 | between two related tree objects, since it can ignore any entries with |
| 1241 | identical object names.</p><p>(Note: in the presence of submodules, trees may also have commits as |
| Junio C Hamano | 4fd58d4 | 2007-09-30 00:51:14 | [diff] [blame] | 1242 | entries. See <a href="#submodules" title="Chapter 8. Submodules">Chapter 8, <i>Submodules</i></a> for documentation.)</p><p>Note that the files all have mode 644 or 755: git actually only pays |
| Junio C Hamano | 597ffcf | 2007-09-17 17:33:15 | [diff] [blame] | 1243 | attention to the executable bit.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="blob-object"></a>Blob Object</h3></div></div></div><p>You can use <a href="git-show.html" target="_top">git-show(1)</a> to examine the contents of a blob; take, |
| 1244 | for example, the blob in the entry for "COPYING" from the tree above:</p><div class="literallayout"><p>$ git show 6ff87c4664<br> |
| 1245 | <br> |
| 1246 | Note that the only valid version of the GPL as far as this project<br> |
| 1247 | is concerned is _this_ particular version of the license (ie v2, not<br> |
| 1248 | v2.2 or v3.x or whatever), unless explicitly otherwise stated.<br> |
| 1249 | ...</p></div><p>A "blob" object is nothing but a binary blob of data. It doesn't refer |
| 1250 | to anything else or have attributes of any kind.</p><p>Since the blob is entirely defined by its data, if two files in a |
| 1251 | directory tree (or in multiple different versions of the repository) |
| 1252 | have the same contents, they will share the same blob object. The object |
| 1253 | is totally independent of its location in the directory tree, and |
| 1254 | renaming a file does not change the object that file is associated with.</p><p>Note that any tree or blob object can be examined using |
| 1255 | <a href="git-show.html" target="_top">git-show(1)</a> with the <revision>:<path> syntax. This can |
| 1256 | sometimes be useful for browsing the contents of a tree that is not |
| 1257 | currently checked out.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="trust"></a>Trust</h3></div></div></div><p>If you receive the SHA1 name of a blob from one source, and its contents |
| 1258 | from another (possibly untrusted) source, you can still trust that those |
| 1259 | contents are correct as long as the SHA1 name agrees. This is because |
| 1260 | the SHA1 is designed so that it is infeasible to find different contents |
| 1261 | that produce the same hash.</p><p>Similarly, you need only trust the SHA1 name of a top-level tree object |
| 1262 | to trust the contents of the entire directory that it refers to, and if |
| 1263 | you receive the SHA1 name of a commit from a trusted source, then you |
| 1264 | can easily verify the entire history of commits reachable through |
| 1265 | parents of that commit, and all of those contents of the trees referred |
| 1266 | to by those commits.</p><p>So to introduce some real trust in the system, the only thing you need |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1267 | to do is to digitally sign just <span class="emphasis"><em>one</em></span> special note, which includes the |
| 1268 | name of a top-level commit. Your digital signature shows others |
| 1269 | that you trust that commit, and the immutability of the history of |
| 1270 | commits tells others that they can trust the whole history.</p><p>In other words, you can easily validate a whole archive by just |
| 1271 | sending out a single email that tells the people the name (SHA1 hash) |
| 1272 | of the top commit, and digitally sign that email using something |
| Junio C Hamano | 597ffcf | 2007-09-17 17:33:15 | [diff] [blame] | 1273 | like GPG/PGP.</p><p>To assist in this, git also provides the tag object…</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="tag-object"></a>Tag Object</h3></div></div></div><p>A tag object contains an object, object type, tag name, the name of the |
| 1274 | person ("tagger") who created the tag, and a message, which may contain |
| 1275 | a signature, as can be seen using the <a href="git-cat-file.html" target="_top">git-cat-file(1)</a>:</p><div class="literallayout"><p>$ git cat-file tag v1.5.0<br> |
| 1276 | object 437b1b20df4b356c9342dac8d38849f24ef44f27<br> |
| 1277 | type commit<br> |
| 1278 | tag v1.5.0<br> |
| 1279 | tagger Junio C Hamano <junkio@cox.net> 1171411200 +0000<br> |
| 1280 | <br> |
| 1281 | GIT 1.5.0<br> |
| 1282 | -----BEGIN PGP SIGNATURE-----<br> |
| 1283 | Version: GnuPG v1.4.6 (GNU/Linux)<br> |
| 1284 | <br> |
| 1285 | iD8DBQBF0lGqwMbZpPMRm5oRAuRiAJ9ohBLd7s2kqjkKlq1qqC57SbnmzQCdG4ui<br> |
| 1286 | nLE/L9aUXdWeTFPron96DLA=<br> |
| 1287 | =2E+0<br> |
| 1288 | -----END PGP SIGNATURE-----</p></div><p>See the <a href="git-tag.html" target="_top">git-tag(1)</a> command to learn how to create and verify tag |
| 1289 | objects. (Note that <a href="git-tag.html" target="_top">git-tag(1)</a> can also be used to create |
| 1290 | "lightweight tags", which are not tag objects at all, but just simple |
| Junio C Hamano | 9810d63 | 2007-09-24 01:05:34 | [diff] [blame] | 1291 | references whose names begin with "refs/tags/").</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="pack-files"></a>How git stores objects efficiently: pack files</h3></div></div></div><p>Newly created objects are initially created in a file named after the |
| Junio C Hamano | 597ffcf | 2007-09-17 17:33:15 | [diff] [blame] | 1292 | object's SHA1 hash (stored in .git/objects).</p><p>Unfortunately this system becomes inefficient once a project has a |
| 1293 | lot of objects. Try this on an old project:</p><div class="literallayout"><p>$ git count-objects<br> |
| 1294 | 6930 objects, 47620 kilobytes</p></div><p>The first number is the number of objects which are kept in |
| 1295 | individual files. The second is the amount of space taken up by |
| 1296 | those "loose" objects.</p><p>You can save space and make git faster by moving these loose objects in |
| 1297 | to a "pack file", which stores a group of objects in an efficient |
| 1298 | compressed format; the details of how pack files are formatted can be |
| 1299 | found in <a href="technical/pack-format.txt" target="_top">technical/pack-format.txt</a>.</p><p>To put the loose objects into a pack, just run git repack:</p><div class="literallayout"><p>$ git repack<br> |
| 1300 | Generating pack...<br> |
| 1301 | Done counting 6020 objects.<br> |
| 1302 | Deltifying 6020 objects.<br> |
| 1303 | 100% (6020/6020) done<br> |
| 1304 | Writing 6020 objects.<br> |
| 1305 | 100% (6020/6020) done<br> |
| 1306 | Total 6020, written 6020 (delta 4070), reused 0 (delta 0)<br> |
| 1307 | Pack pack-3e54ad29d5b2e05838c75df582c65257b8d08e1c created.</p></div><p>You can then run</p><div class="literallayout"><p>$ git prune</p></div><p>to remove any of the "loose" objects that are now contained in the |
| 1308 | pack. This will also remove any unreferenced objects (which may be |
| 1309 | created when, for example, you use "git reset" to remove a commit). |
| 1310 | You can verify that the loose objects are gone by looking at the |
| 1311 | .git/objects directory or by running</p><div class="literallayout"><p>$ git count-objects<br> |
| 1312 | 0 objects, 0 kilobytes</p></div><p>Although the object files are gone, any commands that refer to those |
| 1313 | objects will work exactly as they did before.</p><p>The <a href="git-gc.html" target="_top">git-gc(1)</a> command performs packing, pruning, and more for |
| 1314 | you, so is normally the only high-level command you need.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="dangling-objects"></a>Dangling objects</h3></div></div></div><p>The <a href="git-fsck.html" target="_top">git-fsck(1)</a> command will sometimes complain about dangling |
| 1315 | objects. They are not a problem.</p><p>The most common cause of dangling objects is that you've rebased a |
| 1316 | branch, or you have pulled from somebody else who rebased a branch—see |
| 1317 | <a href="#cleaning-up-history" title="Chapter 5. Rewriting history and maintaining patch series">Chapter 5, <i>Rewriting history and maintaining patch series</i></a>. In that case, the old head of the original |
| 1318 | branch still exists, as does everything it pointed to. The branch |
| 1319 | pointer itself just doesn't, since you replaced it with another one.</p><p>There are also other situations that cause dangling objects. For |
| 1320 | example, a "dangling blob" may arise because you did a "git add" of a |
| 1321 | file, but then, before you actually committed it and made it part of the |
| 1322 | bigger picture, you changed something else in that file and committed |
| Junio C Hamano | 764a667 | 2007-10-23 01:23:31 | [diff] [blame] | 1323 | that <span class="strong"><strong>updated</strong></span> thing—the old state that you added originally ends up |
| Junio C Hamano | 597ffcf | 2007-09-17 17:33:15 | [diff] [blame] | 1324 | not being pointed to by any commit or tree, so it's now a dangling blob |
| 1325 | object.</p><p>Similarly, when the "recursive" merge strategy runs, and finds that |
| 1326 | there are criss-cross merges and thus more than one merge base (which is |
| 1327 | fairly unusual, but it does happen), it will generate one temporary |
| 1328 | midway tree (or possibly even more, if you had lots of criss-crossing |
| 1329 | merges and more than two merge bases) as a temporary internal merge |
| 1330 | base, and again, those are real objects, but the end result will not end |
| 1331 | up pointing to them, so they end up "dangling" in your repository.</p><p>Generally, dangling objects aren't anything to worry about. They can |
| 1332 | even be very useful: if you screw something up, the dangling objects can |
| 1333 | be how you recover your old tree (say, you did a rebase, and realized |
| Junio C Hamano | 764a667 | 2007-10-23 01:23:31 | [diff] [blame] | 1334 | that you really didn't want to—you can look at what dangling objects |
| Junio C Hamano | 597ffcf | 2007-09-17 17:33:15 | [diff] [blame] | 1335 | you have, and decide to reset your head to some old dangling state).</p><p>For commits, you can just use:</p><div class="literallayout"><p>$ gitk <dangling-commit-sha-goes-here> --not --all</p></div><p>This asks for all the history reachable from the given commit but not |
| 1336 | from any branch, tag, or other reference. If you decide it's something |
| 1337 | you want, you can always create a new reference to it, e.g.,</p><div class="literallayout"><p>$ git branch recovered-branch <dangling-commit-sha-goes-here></p></div><p>For blobs and trees, you can't do the same, but you can still examine |
| 1338 | them. You can just do</p><div class="literallayout"><p>$ git show <dangling-blob/tree-sha-goes-here></p></div><p>to show what the contents of the blob were (or, for a tree, basically |
| 1339 | what the "ls" for that directory was), and that may give you some idea |
| 1340 | of what the operation was that left that dangling object.</p><p>Usually, dangling blobs and trees aren't very interesting. They're |
| 1341 | almost always the result of either being a half-way mergebase (the blob |
| 1342 | will often even have the conflict markers from a merge in it, if you |
| 1343 | have had conflicting merges that you fixed up by hand), or simply |
| 1344 | because you interrupted a "git fetch" with ^C or something like that, |
| 1345 | leaving _some_ of the new objects in the object database, but just |
| 1346 | dangling and useless.</p><p>Anyway, once you are sure that you're not interested in any dangling |
| 1347 | state, you can just prune all unreachable objects:</p><div class="literallayout"><p>$ git prune</p></div><p>and they'll be gone. But you should only run "git prune" on a quiescent |
| Junio C Hamano | 764a667 | 2007-10-23 01:23:31 | [diff] [blame] | 1348 | repository—it's kind of like doing a filesystem fsck recovery: you |
| 1349 | don't want to do that while the filesystem is mounted.</p><p>(The same is true of "git-fsck" itself, btw, but since |
| Junio C Hamano | 597ffcf | 2007-09-17 17:33:15 | [diff] [blame] | 1350 | git-fsck never actually <span class="strong"><strong>changes</strong></span> the repository, it just reports |
| 1351 | on what it found, git-fsck itself is never "dangerous" to run. |
| 1352 | Running it while somebody is actually changing the repository can cause |
| 1353 | confusing and scary messages, but it won't actually do anything bad. In |
| 1354 | contrast, running "git prune" while somebody is actively changing the |
| Junio C Hamano | ce3650e | 2007-11-26 04:20:11 | [diff] [blame] | 1355 | repository is a <span class="strong"><strong>BAD</strong></span> idea).</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="recovering-from-repository-corruption"></a>Recovering from repository corruption</h3></div></div></div><p>By design, git treats data trusted to it with caution. However, even in |
| 1356 | the absence of bugs in git itself, it is still possible that hardware or |
| 1357 | operating system errors could corrupt data.</p><p>The first defense against such problems is backups. You can back up a |
| 1358 | git directory using clone, or just using cp, tar, or any other backup |
| 1359 | mechanism.</p><p>As a last resort, you can search for the corrupted objects and attempt |
| 1360 | to replace them by hand. Back up your repository before attempting this |
| 1361 | in case you corrupt things even more in the process.</p><p>We'll assume that the problem is a single missing or corrupted blob, |
| Junio C Hamano | 878cc1e | 2007-12-14 08:35:13 | [diff] [blame] | 1362 | which is sometimes a solvable problem. (Recovering missing trees and |
| Junio C Hamano | ce3650e | 2007-11-26 04:20:11 | [diff] [blame] | 1363 | especially commits is <span class="strong"><strong>much</strong></span> harder).</p><p>Before starting, verify that there is corruption, and figure out where |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 1364 | it is with <a href="git-fsck.html" target="_top">git-fsck(1)</a>; this may be time-consuming.</p><p>Assume the output looks like this:</p><div class="literallayout"><p>$ git fsck --full<br> |
| Junio C Hamano | ce3650e | 2007-11-26 04:20:11 | [diff] [blame] | 1365 | broken link from tree 2d9263c6d23595e7cb2a21e5ebbb53655278dff8<br> |
| 1366 | to blob 4b9458b3786228369c63936db65827de3cc06200<br> |
| 1367 | missing blob 4b9458b3786228369c63936db65827de3cc06200</p></div><p>(Typically there will be some "dangling object" messages too, but they |
| 1368 | aren't interesting.)</p><p>Now you know that blob 4b9458b3 is missing, and that the tree 2d9263c6 |
| 1369 | points to it. If you could find just one copy of that missing blob |
| 1370 | object, possibly in some other repository, you could move it into |
| 1371 | .git/objects/4b/9458b3… and be done. Suppose you can't. You can |
| 1372 | still examine the tree that pointed to it with <a href="git-ls-tree.html" target="_top">git-ls-tree(1)</a>, |
| 1373 | which might output something like:</p><div class="literallayout"><p>$ git ls-tree 2d9263c6d23595e7cb2a21e5ebbb53655278dff8<br> |
| 1374 | 100644 blob 8d14531846b95bfa3564b58ccfb7913a034323b8 .gitignore<br> |
| 1375 | 100644 blob ebf9bf84da0aab5ed944264a5db2a65fe3a3e883 .mailmap<br> |
| 1376 | 100644 blob ca442d313d86dc67e0a2e5d584b465bd382cbf5c COPYING<br> |
| 1377 | ...<br> |
| 1378 | 100644 blob 4b9458b3786228369c63936db65827de3cc06200 myfile<br> |
| 1379 | ...</p></div><p>So now you know that the missing blob was the data for a file named |
| 1380 | "myfile". And chances are you can also identify the directory—let's |
| 1381 | say it's in "somedirectory". If you're lucky the missing copy might be |
| 1382 | the same as the copy you have checked out in your working tree at |
| 1383 | "somedirectory/myfile"; you can test whether that's right with |
| 1384 | <a href="git-hash-object.html" target="_top">git-hash-object(1)</a>:</p><div class="literallayout"><p>$ git hash-object -w somedirectory/myfile</p></div><p>which will create and store a blob object with the contents of |
| 1385 | somedirectory/myfile, and output the sha1 of that object. if you're |
| 1386 | extremely lucky it might be 4b9458b3786228369c63936db65827de3cc06200, in |
| 1387 | which case you've guessed right, and the corruption is fixed!</p><p>Otherwise, you need more information. How do you tell which version of |
| 1388 | the file has been lost?</p><p>The easiest way to do this is with:</p><div class="literallayout"><p>$ git log --raw --all --full-history -- somedirectory/myfile</p></div><p>Because you're asking for raw output, you'll now get something like</p><div class="literallayout"><p>commit abc<br> |
| 1389 | Author:<br> |
| 1390 | Date:<br> |
| 1391 | ...<br> |
| 1392 | :100644 100644 4b9458b... newsha... M somedirectory/myfile<br> |
| 1393 | <br> |
| 1394 | <br> |
| 1395 | commit xyz<br> |
| 1396 | Author:<br> |
| 1397 | Date:<br> |
| 1398 | <br> |
| 1399 | ...<br> |
| 1400 | :100644 100644 oldsha... 4b9458b... M somedirectory/myfile</p></div><p>This tells you that the immediately preceding version of the file was |
| 1401 | "newsha", and that the immediately following version was "oldsha". |
| 1402 | You also know the commit messages that went with the change from oldsha |
| 1403 | to 4b9458b and with the change from 4b9458b to newsha.</p><p>If you've been committing small enough changes, you may now have a good |
| 1404 | shot at reconstructing the contents of the in-between state 4b9458b.</p><p>If you can do that, you can now recreate the missing object with</p><div class="literallayout"><p>$ git hash-object -w <recreated-file></p></div><p>and your repository is good again!</p><p>(Btw, you could have ignored the fsck, and started with doing a</p><div class="literallayout"><p>$ git log --raw --all</p></div><p>and just looked for the sha of the missing object (4b9458b..) in that |
| 1405 | whole thing. It's up to you - git does <span class="strong"><strong>have</strong></span> a lot of information, it is |
| 1406 | just missing one particular blob version.</p></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="the-index"></a>The index</h2></div></div></div><p>The index is a binary file (generally kept in .git/index) containing a |
| Junio C Hamano | 597ffcf | 2007-09-17 17:33:15 | [diff] [blame] | 1407 | sorted list of path names, each with permissions and the SHA1 of a blob |
| 1408 | object; <a href="git-ls-files.html" target="_top">git-ls-files(1)</a> can show you the contents of the index:</p><div class="literallayout"><p>$ git ls-files --stage<br> |
| 1409 | 100644 63c918c667fa005ff12ad89437f2fdc80926e21c 0 .gitignore<br> |
| 1410 | 100644 5529b198e8d14decbe4ad99db3f7fb632de0439d 0 .mailmap<br> |
| 1411 | 100644 6ff87c4664981e4397625791c8ea3bbb5f2279a3 0 COPYING<br> |
| 1412 | 100644 a37b2152bd26be2c2289e1f57a292534a51a93c7 0 Documentation/.gitignore<br> |
| 1413 | 100644 fbefe9a45b00a54b58d94d06eca48b03d40a50e0 0 Documentation/Makefile<br> |
| 1414 | ...<br> |
| 1415 | 100644 2511aef8d89ab52be5ec6a5e46236b4b6bcd07ea 0 xdiff/xtypes.h<br> |
| 1416 | 100644 2ade97b2574a9f77e7ae4002a4e07a6a38e46d07 0 xdiff/xutils.c<br> |
| 1417 | 100644 d5de8292e05e7c36c4b68857c1cf9855e3d2f70a 0 xdiff/xutils.h</p></div><p>Note that in older documentation you may see the index called the |
| 1418 | "current directory cache" or just the "cache". It has three important |
| 1419 | properties:</p><div class="orderedlist"><ol type="1"><li><p> |
| 1420 | The index contains all the information necessary to generate a single |
| 1421 | (uniquely determined) tree object. |
| 1422 | </p><p>For example, running <a href="git-commit.html" target="_top">git-commit(1)</a> generates this tree object |
| 1423 | from the index, stores it in the object database, and uses it as the |
| 1424 | tree object associated with the new commit.</p></li><li><p> |
| 1425 | The index enables fast comparisons between the tree object it defines |
| 1426 | and the working tree. |
| 1427 | </p><p>It does this by storing some additional data for each entry (such as |
| 1428 | the last modified time). This data is not displayed above, and is not |
| 1429 | stored in the created tree object, but it can be used to determine |
| 1430 | quickly which files in the working directory differ from what was |
| 1431 | stored in the index, and thus save git from having to read all of the |
| 1432 | data from such files to look for changes.</p></li><li><p> |
| 1433 | It can efficiently represent information about merge conflicts |
| 1434 | between different tree objects, allowing each pathname to be |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1435 | associated with sufficient information about the trees involved that |
| Junio C Hamano | 597ffcf | 2007-09-17 17:33:15 | [diff] [blame] | 1436 | you can create a three-way merge between them. |
| 1437 | </p><p>We saw in <a href="#conflict-resolution" title="Getting conflict-resolution help during a merge">the section called “Getting conflict-resolution help during a merge”</a> that during a merge the index can |
| 1438 | store multiple versions of a single file (called "stages"). The third |
| 1439 | column in the <a href="git-ls-files.html" target="_top">git-ls-files(1)</a> output above is the stage |
| 1440 | number, and will take on values other than 0 for files with merge |
| 1441 | conflicts.</p></li></ol></div><p>The index is thus a sort of temporary staging area, which is filled with |
| 1442 | a tree which you are in the process of working on.</p><p>If you blow the index away entirely, you generally haven't lost any |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 1443 | information as long as you have the name of the tree that it described.</p></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="submodules"></a>Chapter 8. Submodules</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="section"><a href="#id280263">Pitfalls with submodules</a></span></dt></dl></div><p>Large projects are often composed of smaller, self-contained modules. For |
| Junio C Hamano | 4fd58d4 | 2007-09-30 00:51:14 | [diff] [blame] | 1444 | example, an embedded Linux distribution's source tree would include every |
| 1445 | piece of software in the distribution with some local modifications; a movie |
| 1446 | player might need to build against a specific, known-working version of a |
| 1447 | decompression library; several independent programs might all share the same |
| 1448 | build scripts.</p><p>With centralized revision control systems this is often accomplished by |
| 1449 | including every module in one single repository. Developers can check out |
| 1450 | all modules or only the modules they need to work with. They can even modify |
| 1451 | files across several modules in a single commit while moving things around |
| 1452 | or updating APIs and translations.</p><p>Git does not allow partial checkouts, so duplicating this approach in Git |
| 1453 | would force developers to keep a local copy of modules they are not |
| 1454 | interested in touching. Commits in an enormous checkout would be slower |
| 1455 | than you'd expect as Git would have to scan every directory for changes. |
| 1456 | If modules have a lot of local history, clones would take forever.</p><p>On the plus side, distributed revision control systems can much better |
| 1457 | integrate with external sources. In a centralized model, a single arbitrary |
| 1458 | snapshot of the external project is exported from its own revision control |
| 1459 | and then imported into the local revision control on a vendor branch. All |
| 1460 | the history is hidden. With distributed revision control you can clone the |
| 1461 | entire external history and much more easily follow development and re-merge |
| 1462 | local changes.</p><p>Git's submodule support allows a repository to contain, as a subdirectory, a |
| 1463 | checkout of an external project. Submodules maintain their own identity; |
| 1464 | the submodule support just stores the submodule repository location and |
| 1465 | commit ID, so other developers who clone the containing project |
| 1466 | ("superproject") can easily clone all the submodules at the same revision. |
| 1467 | Partial checkouts of the superproject are possible: you can tell Git to |
| 1468 | clone none, some or all of the submodules.</p><p>The <a href="git-submodule.html" target="_top">git-submodule(1)</a> command is available since Git 1.5.3. Users |
| 1469 | with Git 1.5.2 can look up the submodule commits in the repository and |
| 1470 | manually check them out; earlier versions won't recognize the submodules at |
| 1471 | all.</p><p>To see how submodule support works, create (for example) four example |
| Junio C Hamano | 9810d63 | 2007-09-24 01:05:34 | [diff] [blame] | 1472 | repositories that can be used later as a submodule:</p><div class="literallayout"><p>$ mkdir ~/git<br> |
| 1473 | $ cd ~/git<br> |
| 1474 | $ for i in a b c d<br> |
| 1475 | do<br> |
| 1476 | mkdir $i<br> |
| 1477 | cd $i<br> |
| 1478 | git init<br> |
| 1479 | echo "module $i" > $i.txt<br> |
| 1480 | git add $i.txt<br> |
| 1481 | git commit -m "Initial commit, submodule $i"<br> |
| 1482 | cd ..<br> |
| 1483 | done</p></div><p>Now create the superproject and add all the submodules:</p><div class="literallayout"><p>$ mkdir super<br> |
| 1484 | $ cd super<br> |
| 1485 | $ git init<br> |
| 1486 | $ for i in a b c d<br> |
| 1487 | do<br> |
| 1488 | git submodule add ~/git/$i<br> |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 1489 | done</p></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>Do not use local URLs here if you plan to publish your superproject!</p></div><p>See what files <code class="literal">git-submodule</code> created:</p><div class="literallayout"><p>$ ls -a<br> |
| 1490 | . .. .git .gitmodules a b c d</p></div><p>The <code class="literal">git-submodule add</code> command does a couple of things:</p><div class="itemizedlist"><ul type="disc"><li> |
| Junio C Hamano | 9810d63 | 2007-09-24 01:05:34 | [diff] [blame] | 1491 | It clones the submodule under the current directory and by default checks out |
| 1492 | the master branch. |
| 1493 | </li><li> |
| Junio C Hamano | 4fd58d4 | 2007-09-30 00:51:14 | [diff] [blame] | 1494 | It adds the submodule's clone path to the <a href="gitmodules.html" target="_top">gitmodules(5)</a> file and |
| 1495 | adds this file to the index, ready to be committed. |
| Junio C Hamano | 9810d63 | 2007-09-24 01:05:34 | [diff] [blame] | 1496 | </li><li> |
| 1497 | It adds the submodule's current commit ID to the index, ready to be |
| 1498 | committed. |
| 1499 | </li></ul></div><p>Commit the superproject:</p><div class="literallayout"><p>$ git commit -m "Add submodules a, b, c and d."</p></div><p>Now clone the superproject:</p><div class="literallayout"><p>$ cd ..<br> |
| 1500 | $ git clone super cloned<br> |
| 1501 | $ cd cloned</p></div><p>The submodule directories are there, but they're empty:</p><div class="literallayout"><p>$ ls -a a<br> |
| 1502 | . ..<br> |
| 1503 | $ git submodule status<br> |
| 1504 | -d266b9873ad50488163457f025db7cdd9683d88b a<br> |
| 1505 | -e81d457da15309b4fef4249aba9b50187999670d b<br> |
| 1506 | -c1536a972b9affea0f16e0680ba87332dc059146 c<br> |
| 1507 | -d96249ff5d57de5de093e6baff9e0aafa5276a74 d</p></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>The commit object names shown above would be different for you, but they |
| 1508 | should match the HEAD commit object names of your repositories. You can check |
| 1509 | it by running <code class="literal">git ls-remote ../a</code>.</p></div><p>Pulling down the submodules is a two-step process. First run <code class="literal">git submodule |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 1510 | init</code> to add the submodule repository URLs to <code class="literal">.git/config</code>:</p><div class="literallayout"><p>$ git submodule init</p></div><p>Now use <code class="literal">git-submodule update</code> to clone the repositories and check out the |
| Junio C Hamano | 9810d63 | 2007-09-24 01:05:34 | [diff] [blame] | 1511 | commits specified in the superproject:</p><div class="literallayout"><p>$ git submodule update<br> |
| 1512 | $ cd a<br> |
| 1513 | $ ls -a<br> |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 1514 | . .. .git a.txt</p></div><p>One major difference between <code class="literal">git-submodule update</code> and <code class="literal">git-submodule add</code> is |
| 1515 | that <code class="literal">git-submodule update</code> checks out a specific commit, rather than the tip |
| Junio C Hamano | 9810d63 | 2007-09-24 01:05:34 | [diff] [blame] | 1516 | of a branch. It's like checking out a tag: the head is detached, so you're not |
| 1517 | working on a branch.</p><div class="literallayout"><p>$ git branch<br> |
| 1518 | * (no branch)<br> |
| 1519 | master</p></div><p>If you want to make a change within a submodule and you have a detached head, |
| 1520 | then you should create or checkout a branch, make your changes, publish the |
| 1521 | change within the submodule, and then update the superproject to reference the |
| 1522 | new commit:</p><div class="literallayout"><p>$ git checkout master</p></div><p>or</p><div class="literallayout"><p>$ git checkout -b fix-up</p></div><p>then</p><div class="literallayout"><p>$ echo "adding a line again" >> a.txt<br> |
| 1523 | $ git commit -a -m "Updated the submodule from within the superproject."<br> |
| 1524 | $ git push<br> |
| 1525 | $ cd ..<br> |
| 1526 | $ git diff<br> |
| 1527 | diff --git a/a b/a<br> |
| 1528 | index d266b98..261dfac 160000<br> |
| 1529 | --- a/a<br> |
| 1530 | +++ b/a<br> |
| 1531 | @@ -1 +1 @@<br> |
| 1532 | -Subproject commit d266b9873ad50488163457f025db7cdd9683d88b<br> |
| 1533 | +Subproject commit 261dfac35cb99d380eb966e102c1197139f7fa24<br> |
| 1534 | $ git add a<br> |
| 1535 | $ git commit -m "Updated submodule a."<br> |
| 1536 | $ git push</p></div><p>You have to run <code class="literal">git submodule update</code> after <code class="literal">git pull</code> if you want to update |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 1537 | submodules, too.</p><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id280263"></a>Pitfalls with submodules</h2></div></div></div><p>Always publish the submodule change before publishing the change to the |
| Junio C Hamano | 9810d63 | 2007-09-24 01:05:34 | [diff] [blame] | 1538 | superproject that references it. If you forget to publish the submodule change, |
| 1539 | others won't be able to clone the repository:</p><div class="literallayout"><p>$ cd ~/git/super/a<br> |
| 1540 | $ echo i added another line to this file >> a.txt<br> |
| 1541 | $ git commit -a -m "doing it wrong this time"<br> |
| 1542 | $ cd ..<br> |
| 1543 | $ git add a<br> |
| 1544 | $ git commit -m "Updated submodule a again."<br> |
| 1545 | $ git push<br> |
| 1546 | $ cd ~/git/cloned<br> |
| 1547 | $ git pull<br> |
| 1548 | $ git submodule update<br> |
| 1549 | error: pathspec '261dfac35cb99d380eb966e102c1197139f7fa24' did not match any file(s) known to git.<br> |
| 1550 | Did you forget to 'git add'?<br> |
| 1551 | Unable to checkout '261dfac35cb99d380eb966e102c1197139f7fa24' in submodule path 'a'</p></div><p>You also should not rewind branches in a submodule beyond commits that were |
| 1552 | ever recorded in any superproject.</p><p>It's not safe to run <code class="literal">git submodule update</code> if you've made and committed |
| 1553 | changes within a submodule without checking out a branch first. They will be |
| 1554 | silently overwritten:</p><div class="literallayout"><p>$ cat a.txt<br> |
| 1555 | module a<br> |
| 1556 | $ echo line added from private2 >> a.txt<br> |
| 1557 | $ git commit -a -m "line added inside private2"<br> |
| 1558 | $ cd ..<br> |
| 1559 | $ git submodule update<br> |
| 1560 | Submodule path 'a': checked out 'd266b9873ad50488163457f025db7cdd9683d88b'<br> |
| 1561 | $ cd a<br> |
| 1562 | $ cat a.txt<br> |
| 1563 | module a</p></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>The changes are still visible in the submodule's reflog.</p></div><p>This is not the case if you did not commit your changes.</p></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="low-level-operations"></a>Chapter 9. Low-level git operations</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="section"><a href="#object-manipulation">Object access and manipulation</a></span></dt><dt><span class="section"><a href="#the-workflow">The Workflow</a></span></dt><dd><dl><dt><span class="section"><a href="#working-directory-to-index">working directory -> index</a></span></dt><dt><span class="section"><a href="#index-to-object-database">index -> object database</a></span></dt><dt><span class="section"><a href="#object-database-to-index">object database -> index</a></span></dt><dt><span class="section"><a href="#index-to-working-directory">index -> working directory</a></span></dt><dt><span class="section"><a href="#tying-it-all-together">Tying it all together</a></span></dt></dl></dd><dt><span class="section"><a href="#examining-the-data">Examining the data</a></span></dt><dt><span class="section"><a href="#merging-multiple-trees">Merging multiple trees</a></span></dt><dt><span class="section"><a href="#merging-multiple-trees-2">Merging multiple trees, continued</a></span></dt></dl></div><p>Many of the higher-level commands were originally implemented as shell |
| Junio C Hamano | 597ffcf | 2007-09-17 17:33:15 | [diff] [blame] | 1564 | scripts using a smaller core of low-level git commands. These can still |
| 1565 | be useful when doing unusual things with git, or just as a way to |
| 1566 | understand its inner workings.</p><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="object-manipulation"></a>Object access and manipulation</h2></div></div></div><p>The <a href="git-cat-file.html" target="_top">git-cat-file(1)</a> command can show the contents of any object, |
| 1567 | though the higher-level <a href="git-show.html" target="_top">git-show(1)</a> is usually more useful.</p><p>The <a href="git-commit-tree.html" target="_top">git-commit-tree(1)</a> command allows constructing commits with |
| 1568 | arbitrary parents and trees.</p><p>A tree can be created with <a href="git-write-tree.html" target="_top">git-write-tree(1)</a> and its data can be |
| 1569 | accessed by <a href="git-ls-tree.html" target="_top">git-ls-tree(1)</a>. Two trees can be compared with |
| 1570 | <a href="git-diff-tree.html" target="_top">git-diff-tree(1)</a>.</p><p>A tag is created with <a href="git-mktag.html" target="_top">git-mktag(1)</a>, and the signature can be |
| 1571 | verified by <a href="git-verify-tag.html" target="_top">git-verify-tag(1)</a>, though it is normally simpler to |
| 1572 | use <a href="git-tag.html" target="_top">git-tag(1)</a> for both.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="the-workflow"></a>The Workflow</h2></div></div></div><p>High-level operations such as <a href="git-commit.html" target="_top">git-commit(1)</a>, |
| Junio C Hamano | 764a667 | 2007-10-23 01:23:31 | [diff] [blame] | 1573 | <a href="git-checkout.html" target="_top">git-checkout(1)</a> and <a href="git-reset.html" target="_top">git-reset(1)</a> work by moving data |
| 1574 | between the working tree, the index, and the object database. Git |
| 1575 | provides low-level operations which perform each of these steps |
| 1576 | individually.</p><p>Generally, all "git" operations work on the index file. Some operations |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1577 | work <span class="strong"><strong>purely</strong></span> on the index file (showing the current state of the |
| Junio C Hamano | 597ffcf | 2007-09-17 17:33:15 | [diff] [blame] | 1578 | index), but most operations move data between the index file and either |
| 1579 | the database or the working directory. Thus there are four main |
| 1580 | combinations:</p><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="working-directory-to-index"></a>working directory -> index</h3></div></div></div><p>The <a href="git-update-index.html" target="_top">git-update-index(1)</a> command updates the index with |
| 1581 | information from the working directory. You generally update the |
| 1582 | index information by just specifying the filename you want to update, |
| 1583 | like so:</p><div class="literallayout"><p>$ git update-index filename</p></div><p>but to avoid common mistakes with filename globbing etc, the command |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1584 | will not normally add totally new entries or remove old entries, |
| 1585 | i.e. it will normally just update existing cache entries.</p><p>To tell git that yes, you really do realize that certain files no |
| 1586 | longer exist, or that new files should be added, you |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 1587 | should use the <code class="literal">—remove</code> and <code class="literal">—add</code> flags respectively.</p><p>NOTE! A <code class="literal">—remove</code> flag does <span class="emphasis"><em>not</em></span> mean that subsequent filenames will |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1588 | necessarily be removed: if the files still exist in your directory |
| 1589 | structure, the index will be updated with their new status, not |
| Junio C Hamano | 774239c | 2007-12-01 01:57:43 | [diff] [blame] | 1590 | removed. The only thing <code class="literal">—remove</code> means is that update-index will be |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1591 | considering a removed file to be a valid thing, and if the file really |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 1592 | does not exist any more, it will update the index accordingly.</p><p>As a special case, you can also do <code class="literal">git-update-index —refresh</code>, which |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1593 | will refresh the "stat" information of each index to match the current |
| 1594 | stat information. It will <span class="emphasis"><em>not</em></span> update the object status itself, and |
| 1595 | it will only update the fields that are used to quickly test whether |
| Junio C Hamano | 597ffcf | 2007-09-17 17:33:15 | [diff] [blame] | 1596 | an object still matches its old backing store object.</p><p>The previously introduced <a href="git-add.html" target="_top">git-add(1)</a> is just a wrapper for |
| Junio C Hamano | 764a667 | 2007-10-23 01:23:31 | [diff] [blame] | 1597 | <a href="git-update-index.html" target="_top">git-update-index(1)</a>.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="index-to-object-database"></a>index -> object database</h3></div></div></div><p>You write your current index file to a "tree" object with the program</p><div class="literallayout"><p>$ git write-tree</p></div><p>that doesn't come with any options—it will just write out the |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1598 | current index into the set of tree objects that describe that state, |
| 1599 | and it will return the name of the resulting top-level tree. You can |
| 1600 | use that tree to re-generate the index at any time by going in the |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 1601 | other direction:</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="object-database-to-index"></a>object database -> index</h3></div></div></div><p>You read a "tree" file from the object database, and use that to |
| Junio C Hamano | 764a667 | 2007-10-23 01:23:31 | [diff] [blame] | 1602 | populate (and overwrite—don't do this if your index contains any |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1603 | unsaved state that you might want to restore later!) your current |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 1604 | index. Normal operation is just</p><div class="literallayout"><p>$ git read-tree <sha1 of tree></p></div><p>and your index file will now be equivalent to the tree that you saved |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1605 | earlier. However, that is only your <span class="emphasis"><em>index</em></span> file: your working |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 1606 | directory contents have not been modified.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="index-to-working-directory"></a>index -> working directory</h3></div></div></div><p>You update your working directory from the index by "checking out" |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1607 | files. This is not a very common operation, since normally you'd just |
| 1608 | keep your files updated, and rather than write to your working |
| 1609 | directory, you'd tell the index files about the changes in your |
| 1610 | working directory (i.e. <code class="literal">git-update-index</code>).</p><p>However, if you decide to jump to a new version, or check out somebody |
| 1611 | else's version, or just restore a previous tree, you'd populate your |
| 1612 | index file with read-tree, and then you need to check out the result |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 1613 | with</p><div class="literallayout"><p>$ git checkout-index filename</p></div><p>or, if you want to check out all of the index, use <code class="literal">-a</code>.</p><p>NOTE! git-checkout-index normally refuses to overwrite old files, so |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1614 | if you have an old version of the tree already checked out, you will |
| 1615 | need to use the "-f" flag (<span class="emphasis"><em>before</em></span> the "-a" flag or the filename) to |
| 1616 | <span class="emphasis"><em>force</em></span> the checkout.</p><p>Finally, there are a few odds and ends which are not purely moving |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 1617 | from one representation to the other:</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="tying-it-all-together"></a>Tying it all together</h3></div></div></div><p>To commit a tree you have instantiated with "git-write-tree", you'd |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1618 | create a "commit" object that refers to that tree and the history |
| Junio C Hamano | 764a667 | 2007-10-23 01:23:31 | [diff] [blame] | 1619 | behind it—most notably the "parent" commits that preceded it in |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1620 | history.</p><p>Normally a "commit" has one parent: the previous state of the tree |
| 1621 | before a certain change was made. However, sometimes it can have two |
| 1622 | or more parent commits, in which case we call it a "merge", due to the |
| 1623 | fact that such a commit brings together ("merges") two or more |
| 1624 | previous states represented by other commits.</p><p>In other words, while a "tree" represents a particular directory state |
| 1625 | of a working directory, a "commit" represents that state in "time", |
| 1626 | and explains how we got there.</p><p>You create a commit object by giving it the tree that describes the |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 1627 | state at the time of the commit, and a list of parents:</p><div class="literallayout"><p>$ git commit-tree <tree> -p <parent> [-p <parent2> ..]</p></div><p>and then giving the reason for the commit on stdin (either through |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1628 | redirection from a pipe or file, or by just typing it at the tty).</p><p>git-commit-tree will return the name of the object that represents |
| 1629 | that commit, and you should save it away for later use. Normally, |
| 1630 | you'd commit a new <code class="literal">HEAD</code> state, and while git doesn't care where you |
| 1631 | save the note about that state, in practice we tend to just write the |
| 1632 | result to the file pointed at by <code class="literal">.git/HEAD</code>, so that we can always see |
| 1633 | what the last committed state was.</p><p>Here is an ASCII art by Jon Loeliger that illustrates how |
| 1634 | various pieces fit together.</p><div class="literallayout"><p><br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 1635 | commit-tree<br> |
| 1636 | commit obj<br> |
| 1637 | +----+<br> |
| 1638 | | |<br> |
| 1639 | | |<br> |
| 1640 | V V<br> |
| 1641 | +-----------+<br> |
| 1642 | | Object DB |<br> |
| 1643 | | Backing |<br> |
| 1644 | | Store |<br> |
| 1645 | +-----------+<br> |
| 1646 | ^<br> |
| 1647 | write-tree | |<br> |
| 1648 | tree obj | |<br> |
| 1649 | | | read-tree<br> |
| 1650 | | | tree obj<br> |
| 1651 | V<br> |
| 1652 | +-----------+<br> |
| 1653 | | Index |<br> |
| 1654 | | "cache" |<br> |
| 1655 | +-----------+<br> |
| 1656 | update-index ^<br> |
| 1657 | blob obj | |<br> |
| 1658 | | |<br> |
| 1659 | checkout-index -u | | checkout-index<br> |
| 1660 | stat | | blob obj<br> |
| 1661 | V<br> |
| 1662 | +-----------+<br> |
| 1663 | | Working |<br> |
| 1664 | | Directory |<br> |
| 1665 | +-----------+<br> |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 1666 | </p></div></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="examining-the-data"></a>Examining the data</h2></div></div></div><p>You can examine the data represented in the object database and the |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1667 | index with various helper tools. For every object, you can use |
| 1668 | <a href="git-cat-file.html" target="_top">git-cat-file(1)</a> to examine details about the |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 1669 | object:</p><div class="literallayout"><p>$ git cat-file -t <objectname></p></div><p>shows the type of the object, and once you have the type (which is |
| 1670 | usually implicit in where you find the object), you can use</p><div class="literallayout"><p>$ git cat-file blob|tree|commit|tag <objectname></p></div><p>to show its contents. NOTE! Trees have binary content, and as a result |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1671 | there is a special helper for showing that content, called |
| 1672 | <code class="literal">git-ls-tree</code>, which turns the binary content into a more easily |
| 1673 | readable form.</p><p>It's especially instructive to look at "commit" objects, since those |
| 1674 | tend to be small and fairly self-explanatory. In particular, if you |
| 1675 | follow the convention of having the top commit name in <code class="literal">.git/HEAD</code>, |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 1676 | you can do</p><div class="literallayout"><p>$ git cat-file commit HEAD</p></div><p>to see what the top commit was.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="merging-multiple-trees"></a>Merging multiple trees</h2></div></div></div><p>Git helps you do a three-way merge, which you can expand to n-way by |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1677 | repeating the merge procedure arbitrary times until you finally |
| 1678 | "commit" the state. The normal situation is that you'd only do one |
| 1679 | three-way merge (two parents), and commit it, but if you like to, you |
| 1680 | can do multiple parents in one go.</p><p>To do a three-way merge, you need the two sets of "commit" objects |
| 1681 | that you want to merge, use those to find the closest common parent (a |
| 1682 | third "commit" object), and then use those commit objects to find the |
| 1683 | state of the directory ("tree" object) at these points.</p><p>To get the "base" for the merge, you first look up the common parent |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 1684 | of two commits with</p><div class="literallayout"><p>$ git merge-base <commit1> <commit2></p></div><p>which will return you the commit they are both based on. You should |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1685 | now look up the "tree" objects of those commits, which you can easily |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 1686 | do with (for example)</p><div class="literallayout"><p>$ git cat-file commit <commitname> | head -1</p></div><p>since the tree object information is always the first line in a commit |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1687 | object.</p><p>Once you know the three trees you are going to merge (the one "original" |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 1688 | tree, aka the common tree, and the two "result" trees, aka the branches |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1689 | you want to merge), you do a "merge" read into the index. This will |
| 1690 | complain if it has to throw away your old index contents, so you should |
| Junio C Hamano | 764a667 | 2007-10-23 01:23:31 | [diff] [blame] | 1691 | make sure that you've committed those—in fact you would normally |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1692 | always do a merge against your last commit (which should thus match what |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 1693 | you have in your current index anyway).</p><p>To do the merge, do</p><div class="literallayout"><p>$ git read-tree -m -u <origtree> <yourtree> <targettree></p></div><p>which will do all trivial merge operations for you directly in the |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1694 | index file, and you can just write the result out with |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 1695 | <code class="literal">git-write-tree</code>.</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="merging-multiple-trees-2"></a>Merging multiple trees, continued</h2></div></div></div><p>Sadly, many merges aren't trivial. If there are files that have |
| Junio C Hamano | 764a667 | 2007-10-23 01:23:31 | [diff] [blame] | 1696 | been added, moved or removed, or if both branches have modified the |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1697 | same file, you will be left with an index tree that contains "merge |
| 1698 | entries" in it. Such an index tree can <span class="emphasis"><em>NOT</em></span> be written out to a tree |
| 1699 | object, and you will have to resolve any such merge clashes using |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 1700 | other tools before you can write out the result.</p><p>You can examine such index state with <code class="literal">git ls-files —unmerged</code> |
| 1701 | command. An example:</p><div class="literallayout"><p>$ git read-tree -m $orig HEAD $target<br> |
| 1702 | $ git ls-files --unmerged<br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 1703 | 100644 263414f423d0e4d70dae8fe53fa34614ff3e2860 1 hello.c<br> |
| 1704 | 100644 06fa6a24256dc7e560efa5687fa84b51f0263c3a 2 hello.c<br> |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 1705 | 100644 cc44c73eb783565da5831b4d820c962954019b69 3 hello.c</p></div><p>Each line of the <code class="literal">git ls-files —unmerged</code> output begins with |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1706 | the blob mode bits, blob SHA1, <span class="emphasis"><em>stage number</em></span>, and the |
| 1707 | filename. The <span class="emphasis"><em>stage number</em></span> is git's way to say which tree it |
| 1708 | came from: stage 1 corresponds to <code class="literal">$orig</code> tree, stage 2 <code class="literal">HEAD</code> |
| 1709 | tree, and stage3 <code class="literal">$target</code> tree.</p><p>Earlier we said that trivial merges are done inside |
| 1710 | <code class="literal">git-read-tree -m</code>. For example, if the file did not change |
| 1711 | from <code class="literal">$orig</code> to <code class="literal">HEAD</code> nor <code class="literal">$target</code>, or if the file changed |
| 1712 | from <code class="literal">$orig</code> to <code class="literal">HEAD</code> and <code class="literal">$orig</code> to <code class="literal">$target</code> the same way, |
| 1713 | obviously the final outcome is what is in <code class="literal">HEAD</code>. What the |
| 1714 | above example shows is that file <code class="literal">hello.c</code> was changed from |
| 1715 | <code class="literal">$orig</code> to <code class="literal">HEAD</code> and <code class="literal">$orig</code> to <code class="literal">$target</code> in a different way. |
| 1716 | You could resolve this by running your favorite 3-way merge |
| Junio C Hamano | 3d30fd5 | 2007-05-08 00:32:53 | [diff] [blame] | 1717 | program, e.g. <code class="literal">diff3</code>, <code class="literal">merge</code>, or git's own merge-file, on |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 1718 | the blob objects from these three stages yourself, like this:</p><div class="literallayout"><p>$ git cat-file blob 263414f... >hello.c~1<br> |
| 1719 | $ git cat-file blob 06fa6a2... >hello.c~2<br> |
| 1720 | $ git cat-file blob cc44c73... >hello.c~3<br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 1721 | $ git merge-file hello.c~2 hello.c~1 hello.c~3</p></div><p>This would leave the merge result in <code class="literal">hello.c~2</code> file, along |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1722 | with conflict markers if there are conflicts. After verifying |
| 1723 | the merge result makes sense, you can tell git what the final |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 1724 | merge result for this file is by:</p><div class="literallayout"><p>$ mv -f hello.c~2 hello.c<br> |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 1725 | $ git update-index hello.c</p></div><p>When a path is in unmerged state, running <code class="literal">git-update-index</code> for |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1726 | that path tells git to mark the path resolved.</p><p>The above is the description of a git merge at the lowest level, |
| 1727 | to help you understand what conceptually happens under the hood. |
| 1728 | In practice, nobody, not even git itself, uses three <code class="literal">git-cat-file</code> |
| 1729 | for this. There is <code class="literal">git-merge-index</code> program that extracts the |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 1730 | stages to temporary files and calls a "merge" script on it:</p><div class="literallayout"><p>$ git merge-index git-merge-one-file hello.c</p></div><p>and that is what higher level <code class="literal">git-merge -s resolve</code> is implemented with.</p></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="hacking-git"></a>Chapter 10. Hacking git</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="section"><a href="#object-details">Object storage format</a></span></dt><dt><span class="section"><a href="#birdview-on-the-source-code">A birds-eye view of Git's source code</a></span></dt></dl></div><p>This chapter covers internal details of the git implementation which |
| Junio C Hamano | 597ffcf | 2007-09-17 17:33:15 | [diff] [blame] | 1731 | probably only git developers need to understand.</p><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="object-details"></a>Object storage format</h2></div></div></div><p>All objects have a statically determined "type" which identifies the |
| 1732 | format of the object (i.e. how it is used, and how it can refer to other |
| 1733 | objects). There are currently four different object types: "blob", |
| 1734 | "tree", "commit", and "tag".</p><p>Regardless of object type, all objects share the following |
| 1735 | characteristics: they are all deflated with zlib, and have a header |
| 1736 | that not only specifies their type, but also provides size information |
| 1737 | about the data in the object. It's worth noting that the SHA1 hash |
| 1738 | that is used to name the object is the hash of the original data |
| 1739 | plus this header, so <code class="literal">sha1sum</code> <span class="emphasis"><em>file</em></span> does not match the object name |
| 1740 | for <span class="emphasis"><em>file</em></span>. |
| 1741 | (Historical note: in the dawn of the age of git the hash |
| 1742 | was the sha1 of the <span class="emphasis"><em>compressed</em></span> object.)</p><p>As a result, the general consistency of an object can always be tested |
| 1743 | independently of the contents or the type of the object: all objects can |
| 1744 | be validated by verifying that (a) their hashes match the content of the |
| 1745 | file and (b) the object successfully inflates to a stream of bytes that |
| 1746 | forms a sequence of <ascii type without space> + <space> + <ascii decimal |
| 1747 | size> + <byte\0> + <binary object data>.</p><p>The structured objects can further have their structure and |
| 1748 | connectivity to other objects verified. This is generally done with |
| 1749 | the <code class="literal">git-fsck</code> program, which generates a full dependency graph |
| 1750 | of all objects, and verifies their internal consistency (in addition |
| 1751 | to just verifying their superficial consistency through the hash).</p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="birdview-on-the-source-code"></a>A birds-eye view of Git's source code</h2></div></div></div><p>It is not always easy for new developers to find their way through Git's |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 1752 | source code. This section gives you a little guidance to show where to |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 1753 | start.</p><p>A good place to start is with the contents of the initial commit, with:</p><div class="literallayout"><p>$ git checkout e83c5163</p></div><p>The initial revision lays the foundation for almost everything git has |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 1754 | today, but is small enough to read in one sitting.</p><p>Note that terminology has changed since that revision. For example, the |
| 1755 | README in that revision uses the word "changeset" to describe what we |
| 1756 | now call a <a href="#def_commit_object">commit</a>.</p><p>Also, we do not call it "cache" any more, but "index", however, the |
| 1757 | file is still called <code class="literal">cache.h</code>. Remark: Not much reason to change it now, |
| 1758 | especially since there is no good single name for it anyway, because it is |
| 1759 | basically _the_ header file which is included by _all_ of Git's C sources.</p><p>If you grasp the ideas in that initial commit, you should check out a |
| 1760 | more recent version and skim <code class="literal">cache.h</code>, <code class="literal">object.h</code> and <code class="literal">commit.h</code>.</p><p>In the early days, Git (in the tradition of UNIX) was a bunch of programs |
| 1761 | which were extremely simple, and which you used in scripts, piping the |
| 1762 | output of one into another. This turned out to be good for initial |
| 1763 | development, since it was easier to test new things. However, recently |
| 1764 | many of these parts have become builtins, and some of the core has been |
| 1765 | "libified", i.e. put into libgit.a for performance, portability reasons, |
| 1766 | and to avoid code duplication.</p><p>By now, you know what the index is (and find the corresponding data |
| 1767 | structures in <code class="literal">cache.h</code>), and that there are just a couple of object types |
| 1768 | (blobs, trees, commits and tags) which inherit their common structure from |
| 1769 | <code class="literal">struct object</code>, which is their first member (and thus, you can cast e.g. |
| 1770 | <code class="literal">(struct object *)commit</code> to achieve the _same_ as <code class="literal">&commit->object</code>, i.e. |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 1771 | get at the object name and flags).</p><p>Now is a good point to take a break to let this information sink in.</p><p>Next step: get familiar with the object naming. Read <a href="#naming-commits" title="Naming commits">the section called “Naming commits”</a>. |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 1772 | There are quite a few ways to name an object (and not only revisions!). |
| 1773 | All of these are handled in <code class="literal">sha1_name.c</code>. Just have a quick look at |
| 1774 | the function <code class="literal">get_sha1()</code>. A lot of the special handling is done by |
| 1775 | functions like <code class="literal">get_sha1_basic()</code> or the likes.</p><p>This is just to get you into the groove for the most libified part of Git: |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 1776 | the revision walker.</p><p>Basically, the initial version of <code class="literal">git log</code> was a shell script:</p><div class="literallayout"><p>$ git-rev-list --pretty $(git-rev-parse --default HEAD "$@") | \<br> |
| 1777 | LESS=-S ${PAGER:-less}</p></div><p>What does this mean?</p><p><code class="literal">git-rev-list</code> is the original version of the revision walker, which |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 1778 | _always_ printed a list of revisions to stdout. It is still functional, |
| 1779 | and needs to, since most new Git programs start out as scripts using |
| 1780 | <code class="literal">git-rev-list</code>.</p><p><code class="literal">git-rev-parse</code> is not as important any more; it was only used to filter out |
| 1781 | options that were relevant for the different plumbing commands that were |
| 1782 | called by the script.</p><p>Most of what <code class="literal">git-rev-list</code> did is contained in <code class="literal">revision.c</code> and |
| 1783 | <code class="literal">revision.h</code>. It wraps the options in a struct named <code class="literal">rev_info</code>, which |
| 1784 | controls how and what revisions are walked, and more.</p><p>The original job of <code class="literal">git-rev-parse</code> is now taken by the function |
| 1785 | <code class="literal">setup_revisions()</code>, which parses the revisions and the common command line |
| 1786 | options for the revision walker. This information is stored in the struct |
| 1787 | <code class="literal">rev_info</code> for later consumption. You can do your own command line option |
| 1788 | parsing after calling <code class="literal">setup_revisions()</code>. After that, you have to call |
| 1789 | <code class="literal">prepare_revision_walk()</code> for initialization, and then you can get the |
| 1790 | commits one by one with the function <code class="literal">get_revision()</code>.</p><p>If you are interested in more details of the revision walking process, |
| 1791 | just have a look at the first implementation of <code class="literal">cmd_log()</code>; call |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 1792 | <code class="literal">git show v1.3.0~155^2~4</code> and scroll down to that function (note that you |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 1793 | no longer need to call <code class="literal">setup_pager()</code> directly).</p><p>Nowadays, <code class="literal">git log</code> is a builtin, which means that it is _contained_ in the |
| 1794 | command <code class="literal">git</code>. The source side of a builtin is</p><div class="itemizedlist"><ul type="disc"><li> |
| 1795 | a function called <code class="literal">cmd_<bla></code>, typically defined in <code class="literal">builtin-<bla>.c</code>, |
| 1796 | and declared in <code class="literal">builtin.h</code>, |
| 1797 | </li><li> |
| 1798 | an entry in the <code class="literal">commands[]</code> array in <code class="literal">git.c</code>, and |
| 1799 | </li><li> |
| 1800 | an entry in <code class="literal">BUILTIN_OBJECTS</code> in the <code class="literal">Makefile</code>. |
| 1801 | </li></ul></div><p>Sometimes, more than one builtin is contained in one source file. For |
| 1802 | example, <code class="literal">cmd_whatchanged()</code> and <code class="literal">cmd_log()</code> both reside in <code class="literal">builtin-log.c</code>, |
| 1803 | since they share quite a bit of code. In that case, the commands which are |
| 1804 | _not_ named like the <code class="literal">.c</code> file in which they live have to be listed in |
| 1805 | <code class="literal">BUILT_INS</code> in the <code class="literal">Makefile</code>.</p><p><code class="literal">git log</code> looks more complicated in C than it does in the original script, |
| 1806 | but that allows for a much greater flexibility and performance.</p><p>Here again it is a good point to take a pause.</p><p>Lesson three is: study the code. Really, it is the best way to learn about |
| 1807 | the organization of Git (after you know the basic concepts).</p><p>So, think about something which you are interested in, say, "how can I |
| 1808 | access a blob just knowing the object name of it?". The first step is to |
| 1809 | find a Git command with which you can do it. In this example, it is either |
| 1810 | <code class="literal">git show</code> or <code class="literal">git cat-file</code>.</p><p>For the sake of clarity, let's stay with <code class="literal">git cat-file</code>, because it</p><div class="itemizedlist"><ul type="disc"><li> |
| 1811 | is plumbing, and |
| 1812 | </li><li> |
| 1813 | was around even in the initial commit (it literally went only through |
| 1814 | some 20 revisions as <code class="literal">cat-file.c</code>, was renamed to <code class="literal">builtin-cat-file.c</code> |
| 1815 | when made a builtin, and then saw less than 10 versions). |
| 1816 | </li></ul></div><p>So, look into <code class="literal">builtin-cat-file.c</code>, search for <code class="literal">cmd_cat_file()</code> and look what |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 1817 | it does.</p><div class="literallayout"><p> git_config(git_default_config);<br> |
| 1818 | if (argc != 3)<br> |
| 1819 | usage("git-cat-file [-t|-s|-e|-p|<type>] <sha1>");<br> |
| 1820 | if (get_sha1(argv[2], sha1))<br> |
| 1821 | die("Not a valid object name %s", argv[2]);</p></div><p>Let's skip over the obvious details; the only really interesting part |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 1822 | here is the call to <code class="literal">get_sha1()</code>. It tries to interpret <code class="literal">argv[2]</code> as an |
| 1823 | object name, and if it refers to an object which is present in the current |
| 1824 | repository, it writes the resulting SHA-1 into the variable <code class="literal">sha1</code>.</p><p>Two things are interesting here:</p><div class="itemizedlist"><ul type="disc"><li> |
| 1825 | <code class="literal">get_sha1()</code> returns 0 on _success_. This might surprise some new |
| 1826 | Git hackers, but there is a long tradition in UNIX to return different |
| Junio C Hamano | 764a667 | 2007-10-23 01:23:31 | [diff] [blame] | 1827 | negative numbers in case of different errors—and 0 on success. |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 1828 | </li><li> |
| 1829 | the variable <code class="literal">sha1</code> in the function signature of <code class="literal">get_sha1()</code> is <code class="literal">unsigned |
| 1830 | char *</code>, but is actually expected to be a pointer to <code class="literal">unsigned |
| 1831 | char[20]</code>. This variable will contain the 160-bit SHA-1 of the given |
| 1832 | commit. Note that whenever a SHA-1 is passed as <code class="literal">unsigned char *</code>, it |
| 1833 | is the binary representation, as opposed to the ASCII representation in |
| 1834 | hex characters, which is passed as <code class="literal">char *</code>. |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 1835 | </li></ul></div><p>You will see both of these things throughout the code.</p><p>Now, for the meat:</p><div class="literallayout"><p> case 0:<br> |
| 1836 | buf = read_object_with_reference(sha1, argv[1], &size, NULL);</p></div><p>This is how you read a blob (actually, not only a blob, but any type of |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 1837 | object). To know how the function <code class="literal">read_object_with_reference()</code> actually |
| 1838 | works, find the source code for it (something like <code class="literal">git grep |
| 1839 | read_object_with | grep ":[a-z]"</code> in the git repository), and read |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 1840 | the source.</p><p>To find out how the result can be used, just read on in <code class="literal">cmd_cat_file()</code>:</p><div class="literallayout"><p> write_or_die(1, buf, size);</p></div><p>Sometimes, you do not know where to look for a feature. In many such cases, |
| Junio C Hamano | fce7c7e | 2008-07-02 03:06:38 | [diff] [blame^] | 1841 | it helps to search through the output of <code class="literal">git log</code>, and then <code class="literal">git-show</code> the |
| 1842 | corresponding commit.</p><p>Example: If you know that there was some test case for <code class="literal">git-bundle</code>, but |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 1843 | do not remember where it was (yes, you _could_ <code class="literal">git grep bundle t/</code>, but that |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 1844 | does not illustrate the point!):</p><div class="literallayout"><p>$ git log --no-merges t/</p></div><p>In the pager (<code class="literal">less</code>), just search for "bundle", go a few lines back, |
| 1845 | and see that it is in commit 18449ab0… Now just copy this object name, |
| 1846 | and paste it into the command line</p><div class="literallayout"><p>$ git show 18449ab0</p></div><p>Voila.</p><p>Another example: Find out what to do in order to make some script a |
| 1847 | builtin:</p><div class="literallayout"><p>$ git log --no-merges --diff-filter=A builtin-*.c</p></div><p>You see, Git is actually the best tool to find out about the source of Git |
| Junio C Hamano | 9810d63 | 2007-09-24 01:05:34 | [diff] [blame] | 1848 | itself!</p></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="glossary"></a>Chapter 11. GIT Glossary</h2></div></div></div><div class="variablelist"><dl><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1849 | <a name="def_alternate_object_database"></a>alternate object database |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1850 | </span></dt><dd> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 1851 | Via the alternates mechanism, a <a href="#def_repository">repository</a> |
| 1852 | can inherit part of its <a href="#def_object_database">object database</a> |
| 1853 | from another object database, which is called "alternate". |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1854 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1855 | <a name="def_bare_repository"></a>bare repository |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1856 | </span></dt><dd> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 1857 | A bare repository is normally an appropriately |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1858 | named <a href="#def_directory">directory</a> with a <code class="literal">.git</code> suffix that does not |
| 1859 | have a locally checked-out copy of any of the files under |
| Junio C Hamano | 3646098 | 2007-05-27 04:29:12 | [diff] [blame] | 1860 | revision control. That is, all of the <code class="literal">git</code> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1861 | administrative and control files that would normally be present in the |
| 1862 | hidden <code class="literal">.git</code> sub-directory are directly present in the |
| 1863 | <code class="literal">repository.git</code> directory instead, |
| 1864 | and no other files are present and checked out. Usually publishers of |
| 1865 | public repositories make bare repositories available. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1866 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1867 | <a name="def_blob_object"></a>blob object |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1868 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1869 | Untyped <a href="#def_object">object</a>, e.g. the contents of a file. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1870 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1871 | <a name="def_branch"></a>branch |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1872 | </span></dt><dd> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 1873 | A "branch" is an active line of development. The most recent |
| 1874 | <a href="#def_commit">commit</a> on a branch is referred to as the tip of |
| 1875 | that branch. The tip of the branch is referenced by a branch |
| 1876 | <a href="#def_head">head</a>, which moves forward as additional development |
| 1877 | is done on the branch. A single git |
| 1878 | <a href="#def_repository">repository</a> can track an arbitrary number of |
| 1879 | branches, but your <a href="#def_working_tree">working tree</a> is |
| 1880 | associated with just one of them (the "current" or "checked out" |
| 1881 | branch), and <a href="#def_HEAD">HEAD</a> points to that branch. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1882 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1883 | <a name="def_cache"></a>cache |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1884 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1885 | Obsolete for: <a href="#def_index">index</a>. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1886 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1887 | <a name="def_chain"></a>chain |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1888 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1889 | A list of objects, where each <a href="#def_object">object</a> in the list contains |
| 1890 | a reference to its successor (for example, the successor of a |
| Junio C Hamano | 3646098 | 2007-05-27 04:29:12 | [diff] [blame] | 1891 | <a href="#def_commit">commit</a> could be one of its <a href="#def_parent">parents</a>). |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1892 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1893 | <a name="def_changeset"></a>changeset |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1894 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1895 | BitKeeper/cvsps speak for "<a href="#def_commit">commit</a>". Since git does not |
| 1896 | store changes, but states, it really does not make sense to use the term |
| 1897 | "changesets" with git. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1898 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1899 | <a name="def_checkout"></a>checkout |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1900 | </span></dt><dd> |
| Junio C Hamano | a14a403 | 2008-03-25 09:11:02 | [diff] [blame] | 1901 | The action of updating all or part of the |
| 1902 | <a href="#def_working_tree">working tree</a> with a <a href="#def_tree_object">tree object</a> |
| 1903 | or <a href="#def_blob_object">blob</a> from the |
| 1904 | <a href="#def_object_database">object database</a>, and updating the |
| 1905 | <a href="#def_index">index</a> and <a href="#def_HEAD">HEAD</a> if the whole working tree has |
| 1906 | been pointed at a new <a href="#def_branch">branch</a>. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1907 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1908 | <a name="def_cherry-picking"></a>cherry-picking |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1909 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1910 | In <a href="#def_SCM">SCM</a> jargon, "cherry pick" means to choose a subset of |
| 1911 | changes out of a series of changes (typically commits) and record them |
| Junio C Hamano | 764a667 | 2007-10-23 01:23:31 | [diff] [blame] | 1912 | as a new series of changes on top of a different codebase. In GIT, this is |
| 1913 | performed by the "git cherry-pick" command to extract the change introduced |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1914 | by an existing <a href="#def_commit">commit</a> and to record it based on the tip |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 1915 | of the current <a href="#def_branch">branch</a> as a new commit. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1916 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1917 | <a name="def_clean"></a>clean |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1918 | </span></dt><dd> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 1919 | A <a href="#def_working_tree">working tree</a> is clean, if it |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1920 | corresponds to the <a href="#def_revision">revision</a> referenced by the current |
| 1921 | <a href="#def_head">head</a>. Also see "<a href="#def_dirty">dirty</a>". |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1922 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1923 | <a name="def_commit"></a>commit |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 1924 | </span></dt><dd><p> |
| 1925 | As a noun: A single point in the |
| 1926 | git history; the entire history of a project is represented as a |
| 1927 | set of interrelated commits. The word "commit" is often |
| 1928 | used by git in the same places other revision control systems |
| 1929 | use the words "revision" or "version". Also used as a short |
| 1930 | hand for <a href="#def_commit_object">commit object</a>. |
| 1931 | </p><p>As a verb: The action of storing a new snapshot of the project's |
| 1932 | state in the git history, by creating a new commit representing the current |
| 1933 | state of the <a href="#def_index">index</a> and advancing <a href="#def_HEAD">HEAD</a> |
| 1934 | to point at the new commit.</p></dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1935 | <a name="def_commit_object"></a>commit object |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1936 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1937 | An <a href="#def_object">object</a> which contains the information about a |
| Junio C Hamano | 3646098 | 2007-05-27 04:29:12 | [diff] [blame] | 1938 | particular <a href="#def_revision">revision</a>, such as <a href="#def_parent">parents</a>, committer, |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1939 | author, date and the <a href="#def_tree_object">tree object</a> which corresponds |
| 1940 | to the top <a href="#def_directory">directory</a> of the stored |
| Junio C Hamano | 3646098 | 2007-05-27 04:29:12 | [diff] [blame] | 1941 | revision. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1942 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1943 | <a name="def_core_git"></a>core git |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1944 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1945 | Fundamental data structures and utilities of git. Exposes only limited |
| 1946 | source code management tools. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1947 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1948 | <a name="def_DAG"></a>DAG |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1949 | </span></dt><dd> |
| Junio C Hamano | 9e1793f | 2008-06-02 07:31:16 | [diff] [blame] | 1950 | Directed acyclic graph. The <a href="#def_commit_object">commit objects</a> form a |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1951 | directed acyclic graph, because they have parents (directed), and the |
| Junio C Hamano | 9e1793f | 2008-06-02 07:31:16 | [diff] [blame] | 1952 | graph of commit objects is acyclic (there is no <a href="#def_chain">chain</a> |
| 1953 | which begins and ends with the same <a href="#def_object">object</a>). |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1954 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1955 | <a name="def_dangling_object"></a>dangling object |
| Junio C Hamano | aa83a7d | 2007-03-05 02:37:29 | [diff] [blame] | 1956 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1957 | An <a href="#def_unreachable_object">unreachable object</a> which is not |
| 1958 | <a href="#def_reachable">reachable</a> even from other unreachable objects; a |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 1959 | dangling object has no references to it from any |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1960 | reference or <a href="#def_object">object</a> in the <a href="#def_repository">repository</a>. |
| Junio C Hamano | aa83a7d | 2007-03-05 02:37:29 | [diff] [blame] | 1961 | </dd><dt><span class="term"> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 1962 | <a name="def_detached_HEAD"></a>detached HEAD |
| 1963 | </span></dt><dd> |
| 1964 | Normally the <a href="#def_HEAD">HEAD</a> stores the name of a |
| Junio C Hamano | 3646098 | 2007-05-27 04:29:12 | [diff] [blame] | 1965 | <a href="#def_branch">branch</a>. However, git also allows you to <a href="#def_checkout">check out</a> |
| 1966 | an arbitrary <a href="#def_commit">commit</a> that isn't necessarily the tip of any |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 1967 | particular branch. In this case HEAD is said to be "detached". |
| 1968 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1969 | <a name="def_dircache"></a>dircache |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1970 | </span></dt><dd> |
| Junio C Hamano | 3646098 | 2007-05-27 04:29:12 | [diff] [blame] | 1971 | You are <span class="strong"><strong>waaaaay</strong></span> behind. See <a href="#def_index">index</a>. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1972 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1973 | <a name="def_directory"></a>directory |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1974 | </span></dt><dd> |
| 1975 | The list you get with "ls" :-) |
| 1976 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1977 | <a name="def_dirty"></a>dirty |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1978 | </span></dt><dd> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 1979 | A <a href="#def_working_tree">working tree</a> is said to be "dirty" if |
| Junio C Hamano | 3646098 | 2007-05-27 04:29:12 | [diff] [blame] | 1980 | it contains modifications which have not been <a href="#def_commit">committed</a> to the current |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1981 | <a href="#def_branch">branch</a>. |
| 1982 | </dd><dt><span class="term"> |
| 1983 | <a name="def_ent"></a>ent |
| 1984 | </span></dt><dd> |
| 1985 | Favorite synonym to "<a href="#def_tree-ish">tree-ish</a>" by some total geeks. See |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1986 | <code class="literal">http://en.wikipedia.org/wiki/Ent_(Middle-earth)</code> for an in-depth |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1987 | explanation. Avoid this term, not to confuse people. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1988 | </dd><dt><span class="term"> |
| Junio C Hamano | 3646098 | 2007-05-27 04:29:12 | [diff] [blame] | 1989 | <a name="def_evil_merge"></a>evil merge |
| 1990 | </span></dt><dd> |
| 1991 | An evil merge is a <a href="#def_merge">merge</a> that introduces changes that |
| 1992 | do not appear in any <a href="#def_parent">parent</a>. |
| 1993 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1994 | <a name="def_fast_forward"></a>fast forward |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 1995 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 1996 | A fast-forward is a special type of <a href="#def_merge">merge</a> where you have a |
| 1997 | <a href="#def_revision">revision</a> and you are "merging" another |
| 1998 | <a href="#def_branch">branch</a>'s changes that happen to be a descendant of what |
| 1999 | you have. In such these cases, you do not make a new <a href="#def_merge">merge</a> |
| 2000 | <a href="#def_commit">commit</a> but instead just update to his |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2001 | revision. This will happen frequently on a |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2002 | <a href="#def_tracking_branch">tracking branch</a> of a remote |
| 2003 | <a href="#def_repository">repository</a>. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2004 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2005 | <a name="def_fetch"></a>fetch |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2006 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2007 | Fetching a <a href="#def_branch">branch</a> means to get the |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2008 | branch's <a href="#def_head_ref">head ref</a> from a remote |
| 2009 | <a href="#def_repository">repository</a>, to find out which objects are |
| 2010 | missing from the local <a href="#def_object_database">object database</a>, |
| 2011 | and to get them, too. See also <a href="git-fetch.html" target="_top">git-fetch(1)</a>. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2012 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2013 | <a name="def_file_system"></a>file system |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2014 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2015 | Linus Torvalds originally designed git to be a user space file system, |
| 2016 | i.e. the infrastructure to hold files and directories. That ensured the |
| 2017 | efficiency and speed of git. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2018 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2019 | <a name="def_git_archive"></a>git archive |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2020 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2021 | Synonym for <a href="#def_repository">repository</a> (for arch people). |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2022 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2023 | <a name="def_grafts"></a>grafts |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2024 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2025 | Grafts enables two otherwise different lines of development to be joined |
| 2026 | together by recording fake ancestry information for commits. This way |
| Junio C Hamano | 3646098 | 2007-05-27 04:29:12 | [diff] [blame] | 2027 | you can make git pretend the set of <a href="#def_parent">parents</a> a <a href="#def_commit">commit</a> has |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2028 | is different from what was recorded when the commit was |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2029 | created. Configured via the <code class="literal">.git/info/grafts</code> file. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2030 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2031 | <a name="def_hash"></a>hash |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2032 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2033 | In git's context, synonym to <a href="#def_object_name">object name</a>. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2034 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2035 | <a name="def_head"></a>head |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2036 | </span></dt><dd> |
| Junio C Hamano | 3646098 | 2007-05-27 04:29:12 | [diff] [blame] | 2037 | A <a href="#def_ref">named reference</a> to the <a href="#def_commit">commit</a> at the tip of a |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2038 | <a href="#def_branch">branch</a>. Heads are stored in |
| 2039 | <code class="literal">$GIT_DIR/refs/heads/</code>, except when using packed refs. (See |
| 2040 | <a href="git-pack-refs.html" target="_top">git-pack-refs(1)</a>.) |
| 2041 | </dd><dt><span class="term"> |
| 2042 | <a name="def_HEAD"></a>HEAD |
| 2043 | </span></dt><dd> |
| Junio C Hamano | 3646098 | 2007-05-27 04:29:12 | [diff] [blame] | 2044 | The current <a href="#def_branch">branch</a>. In more detail: Your <a href="#def_working_tree">working tree</a> is normally derived from the state of the tree |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2045 | referred to by HEAD. HEAD is a reference to one of the |
| 2046 | <a href="#def_head">heads</a> in your repository, except when using a |
| 2047 | <a href="#def_detached_HEAD">detached HEAD</a>, in which case it may |
| 2048 | reference an arbitrary commit. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2049 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2050 | <a name="def_head_ref"></a>head ref |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2051 | </span></dt><dd> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2052 | A synonym for <a href="#def_head">head</a>. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2053 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2054 | <a name="def_hook"></a>hook |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2055 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2056 | During the normal execution of several git commands, call-outs are made |
| 2057 | to optional scripts that allow a developer to add functionality or |
| 2058 | checking. Typically, the hooks allow for a command to be pre-verified |
| 2059 | and potentially aborted, and allow for a post-notification after the |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2060 | operation is done. The hook scripts are found in the |
| Junio C Hamano | 3646098 | 2007-05-27 04:29:12 | [diff] [blame] | 2061 | <code class="literal">$GIT_DIR/hooks/</code> directory, and are enabled by simply |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2062 | making them executable. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2063 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2064 | <a name="def_index"></a>index |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2065 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2066 | A collection of files with stat information, whose contents are stored |
| Junio C Hamano | 3646098 | 2007-05-27 04:29:12 | [diff] [blame] | 2067 | as objects. The index is a stored version of your |
| 2068 | <a href="#def_working_tree">working tree</a>. Truth be told, it can also contain a second, and even |
| 2069 | a third version of a working tree, which are used |
| 2070 | when <a href="#def_merge">merging</a>. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2071 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2072 | <a name="def_index_entry"></a>index entry |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2073 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2074 | The information regarding a particular file, stored in the |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2075 | <a href="#def_index">index</a>. An index entry can be unmerged, if a |
| 2076 | <a href="#def_merge">merge</a> was started, but not yet finished (i.e. if |
| 2077 | the index contains multiple versions of that file). |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2078 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2079 | <a name="def_master"></a>master |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2080 | </span></dt><dd> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2081 | The default development <a href="#def_branch">branch</a>. Whenever you |
| 2082 | create a git <a href="#def_repository">repository</a>, a branch named |
| 2083 | "master" is created, and becomes the active branch. In most |
| 2084 | cases, this contains the local development, though that is |
| 2085 | purely by convention and is not required. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2086 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2087 | <a name="def_merge"></a>merge |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2088 | </span></dt><dd><p> |
| 2089 | As a verb: To bring the contents of another |
| 2090 | <a href="#def_branch">branch</a> (possibly from an external |
| 2091 | <a href="#def_repository">repository</a>) into the current branch. In the |
| 2092 | case where the merged-in branch is from a different repository, |
| 2093 | this is done by first <a href="#def_fetch">fetching</a> the remote branch |
| 2094 | and then merging the result into the current branch. This |
| 2095 | combination of fetch and merge operations is called a |
| 2096 | <a href="#def_pull">pull</a>. Merging is performed by an automatic process |
| 2097 | that identifies changes made since the branches diverged, and |
| 2098 | then applies all those changes together. In cases where changes |
| 2099 | conflict, manual intervention may be required to complete the |
| 2100 | merge. |
| 2101 | </p><p>As a noun: unless it is a <a href="#def_fast_forward">fast forward</a>, a |
| 2102 | successful merge results in the creation of a new <a href="#def_commit">commit</a> |
| 2103 | representing the result of the merge, and having as |
| 2104 | <a href="#def_parent">parents</a> the tips of the merged <a href="#def_branch">branches</a>. |
| 2105 | This commit is referred to as a "merge commit", or sometimes just a |
| 2106 | "merge".</p></dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2107 | <a name="def_object"></a>object |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2108 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2109 | The unit of storage in git. It is uniquely identified by the |
| 2110 | <a href="#def_SHA1">SHA1</a> of its contents. Consequently, an |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2111 | object can not be changed. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2112 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2113 | <a name="def_object_database"></a>object database |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2114 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2115 | Stores a set of "objects", and an individual <a href="#def_object">object</a> is |
| 2116 | identified by its <a href="#def_object_name">object name</a>. The objects usually |
| 2117 | live in <code class="literal">$GIT_DIR/objects/</code>. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2118 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2119 | <a name="def_object_identifier"></a>object identifier |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2120 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2121 | Synonym for <a href="#def_object_name">object name</a>. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2122 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2123 | <a name="def_object_name"></a>object name |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2124 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2125 | The unique identifier of an <a href="#def_object">object</a>. The <a href="#def_hash">hash</a> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2126 | of the object's contents using the Secure Hash Algorithm |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2127 | 1 and usually represented by the 40 character hexadecimal encoding of |
| Junio C Hamano | 3a70234 | 2007-12-12 21:34:02 | [diff] [blame] | 2128 | the <a href="#def_hash">hash</a> of the object. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2129 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2130 | <a name="def_object_type"></a>object type |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2131 | </span></dt><dd> |
| Junio C Hamano | 9e1793f | 2008-06-02 07:31:16 | [diff] [blame] | 2132 | One of the identifiers "<a href="#def_commit_object">commit</a>", |
| 2133 | "<a href="#def_tree_object">tree</a>", "<a href="#def_tag_object">tag</a>" or |
| 2134 | "<a href="#def_blob_object">blob</a>" describing the type of an |
| 2135 | <a href="#def_object">object</a>. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2136 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2137 | <a name="def_octopus"></a>octopus |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2138 | </span></dt><dd> |
| Junio C Hamano | 3646098 | 2007-05-27 04:29:12 | [diff] [blame] | 2139 | To <a href="#def_merge">merge</a> more than two <a href="#def_branch">branches</a>. Also denotes an |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2140 | intelligent predator. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2141 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2142 | <a name="def_origin"></a>origin |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2143 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2144 | The default upstream <a href="#def_repository">repository</a>. Most projects have |
| 2145 | at least one upstream project which they track. By default |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2146 | <span class="emphasis"><em>origin</em></span> is used for that purpose. New upstream updates |
| Junio C Hamano | 3646098 | 2007-05-27 04:29:12 | [diff] [blame] | 2147 | will be fetched into remote <a href="#def_tracking_branch">tracking branches</a> named |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2148 | origin/name-of-upstream-branch, which you can see using |
| Junio C Hamano | 3646098 | 2007-05-27 04:29:12 | [diff] [blame] | 2149 | "<code class="literal">git branch -r</code>". |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2150 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2151 | <a name="def_pack"></a>pack |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2152 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2153 | A set of objects which have been compressed into one file (to save space |
| 2154 | or to transmit them efficiently). |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2155 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2156 | <a name="def_pack_index"></a>pack index |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2157 | </span></dt><dd> |
| 2158 | The list of identifiers, and other information, of the objects in a |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2159 | <a href="#def_pack">pack</a>, to assist in efficiently accessing the contents of a |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2160 | pack. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2161 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2162 | <a name="def_parent"></a>parent |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2163 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2164 | A <a href="#def_commit_object">commit object</a> contains a (possibly empty) list |
| 2165 | of the logical predecessor(s) in the line of development, i.e. its |
| 2166 | parents. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2167 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2168 | <a name="def_pickaxe"></a>pickaxe |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2169 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2170 | The term <a href="#def_pickaxe">pickaxe</a> refers to an option to the diffcore |
| 2171 | routines that help select changes that add or delete a given text |
| Junio C Hamano | 764a667 | 2007-10-23 01:23:31 | [diff] [blame] | 2172 | string. With the <code class="literal">—pickaxe-all</code> option, it can be used to view the full |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2173 | <a href="#def_changeset">changeset</a> that introduced or removed, say, a |
| 2174 | particular line of text. See <a href="git-diff.html" target="_top">git-diff(1)</a>. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2175 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2176 | <a name="def_plumbing"></a>plumbing |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2177 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2178 | Cute name for <a href="#def_core_git">core git</a>. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2179 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2180 | <a name="def_porcelain"></a>porcelain |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2181 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2182 | Cute name for programs and program suites depending on |
| 2183 | <a href="#def_core_git">core git</a>, presenting a high level access to |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2184 | core git. Porcelains expose more of a <a href="#def_SCM">SCM</a> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2185 | interface than the <a href="#def_plumbing">plumbing</a>. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2186 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2187 | <a name="def_pull"></a>pull |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2188 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2189 | Pulling a <a href="#def_branch">branch</a> means to <a href="#def_fetch">fetch</a> it and |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2190 | <a href="#def_merge">merge</a> it. See also <a href="git-pull.html" target="_top">git-pull(1)</a>. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2191 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2192 | <a name="def_push"></a>push |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2193 | </span></dt><dd> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2194 | Pushing a <a href="#def_branch">branch</a> means to get the branch's |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2195 | <a href="#def_head_ref">head ref</a> from a remote <a href="#def_repository">repository</a>, |
| Junio C Hamano | 764a667 | 2007-10-23 01:23:31 | [diff] [blame] | 2196 | find out if it is a direct ancestor to the branch's local |
| 2197 | head ref, and in that case, putting all |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2198 | objects, which are <a href="#def_reachable">reachable</a> from the local |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2199 | head ref, and which are missing from the remote |
| 2200 | repository, into the remote |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2201 | <a href="#def_object_database">object database</a>, and updating the remote |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2202 | head ref. If the remote <a href="#def_head">head</a> is not an |
| 2203 | ancestor to the local head, the push fails. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2204 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2205 | <a name="def_reachable"></a>reachable |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2206 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2207 | All of the ancestors of a given <a href="#def_commit">commit</a> are said to be |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2208 | "reachable" from that commit. More |
| 2209 | generally, one <a href="#def_object">object</a> is reachable from |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2210 | another if we can reach the one from the other by a <a href="#def_chain">chain</a> |
| 2211 | that follows <a href="#def_tag">tags</a> to whatever they tag, |
| 2212 | <a href="#def_commit_object">commits</a> to their parents or trees, and |
| 2213 | <a href="#def_tree_object">trees</a> to the trees or <a href="#def_blob_object">blobs</a> |
| 2214 | that they contain. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2215 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2216 | <a name="def_rebase"></a>rebase |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2217 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2218 | To reapply a series of changes from a <a href="#def_branch">branch</a> to a |
| 2219 | different base, and reset the <a href="#def_head">head</a> of that branch |
| 2220 | to the result. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2221 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2222 | <a name="def_ref"></a>ref |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2223 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2224 | A 40-byte hex representation of a <a href="#def_SHA1">SHA1</a> or a name that |
| 2225 | denotes a particular <a href="#def_object">object</a>. These may be stored in |
| 2226 | <code class="literal">$GIT_DIR/refs/</code>. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2227 | </dd><dt><span class="term"> |
| Junio C Hamano | bb0f404 | 2007-07-04 06:41:40 | [diff] [blame] | 2228 | <a name="def_reflog"></a>reflog |
| 2229 | </span></dt><dd> |
| 2230 | A reflog shows the local "history" of a ref. In other words, |
| 2231 | it can tell you what the 3rd last revision in _this_ repository |
| 2232 | was, and what was the current state in _this_ repository, |
| 2233 | yesterday 9:14pm. See <a href="git-reflog.html" target="_top">git-reflog(1)</a> for details. |
| 2234 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2235 | <a name="def_refspec"></a>refspec |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2236 | </span></dt><dd> |
| Junio C Hamano | 3646098 | 2007-05-27 04:29:12 | [diff] [blame] | 2237 | A "refspec" is used by <a href="#def_fetch">fetch</a> and |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2238 | <a href="#def_push">push</a> to describe the mapping between remote |
| 2239 | <a href="#def_ref">ref</a> and local ref. They are combined with a colon in |
| 2240 | the format <src>:<dst>, preceded by an optional plus sign, +. |
| 2241 | For example: <code class="literal">git fetch $URL |
| 2242 | refs/heads/master:refs/heads/origin</code> means "grab the master |
| 2243 | <a href="#def_branch">branch</a> <a href="#def_head">head</a> from the $URL and store |
| 2244 | it as my origin branch head". And <code class="literal">git push |
| 2245 | $URL refs/heads/master:refs/heads/to-upstream</code> means "publish my |
| 2246 | master branch head as to-upstream branch at $URL". See also |
| Junio C Hamano | 764a667 | 2007-10-23 01:23:31 | [diff] [blame] | 2247 | <a href="git-push.html" target="_top">git-push(1)</a>. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2248 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2249 | <a name="def_repository"></a>repository |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2250 | </span></dt><dd> |
| Junio C Hamano | 3646098 | 2007-05-27 04:29:12 | [diff] [blame] | 2251 | A collection of <a href="#def_ref">refs</a> together with an |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2252 | <a href="#def_object_database">object database</a> containing all objects |
| 2253 | which are <a href="#def_reachable">reachable</a> from the refs, possibly |
| Junio C Hamano | 3646098 | 2007-05-27 04:29:12 | [diff] [blame] | 2254 | accompanied by meta data from one or more <a href="#def_porcelain">porcelains</a>. A |
| 2255 | repository can share an object database with other repositories |
| 2256 | via <a href="#def_alternate_object_database">alternates mechanism</a>. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2257 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2258 | <a name="def_resolve"></a>resolve |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2259 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2260 | The action of fixing up manually what a failed automatic |
| 2261 | <a href="#def_merge">merge</a> left behind. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2262 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2263 | <a name="def_revision"></a>revision |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2264 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2265 | A particular state of files and directories which was stored in the |
| 2266 | <a href="#def_object_database">object database</a>. It is referenced by a |
| 2267 | <a href="#def_commit_object">commit object</a>. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2268 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2269 | <a name="def_rewind"></a>rewind |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2270 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2271 | To throw away part of the development, i.e. to assign the |
| 2272 | <a href="#def_head">head</a> to an earlier <a href="#def_revision">revision</a>. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2273 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2274 | <a name="def_SCM"></a>SCM |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2275 | </span></dt><dd> |
| 2276 | Source code management (tool). |
| 2277 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2278 | <a name="def_SHA1"></a>SHA1 |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2279 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2280 | Synonym for <a href="#def_object_name">object name</a>. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2281 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2282 | <a name="def_shallow_repository"></a>shallow repository |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2283 | </span></dt><dd> |
| Junio C Hamano | 3646098 | 2007-05-27 04:29:12 | [diff] [blame] | 2284 | A shallow <a href="#def_repository">repository</a> has an incomplete |
| 2285 | history some of whose <a href="#def_commit">commits</a> have <a href="#def_parent">parents</a> cauterized away (in other |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2286 | words, git is told to pretend that these commits do not have the |
| 2287 | parents, even though they are recorded in the <a href="#def_commit_object">commit object</a>). This is sometimes useful when you are interested only in the |
| 2288 | recent history of a project even though the real history recorded in the |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2289 | upstream is much larger. A shallow repository |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 2290 | is created by giving the <code class="literal">—depth</code> option to <a href="git-clone.html" target="_top">git-clone(1)</a>, and |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2291 | its history can be later deepened with <a href="git-fetch.html" target="_top">git-fetch(1)</a>. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2292 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2293 | <a name="def_symref"></a>symref |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2294 | </span></dt><dd> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2295 | Symbolic reference: instead of containing the <a href="#def_SHA1">SHA1</a> |
| 2296 | id itself, it is of the format <span class="emphasis"><em>ref: refs/some/thing</em></span> and when |
| 2297 | referenced, it recursively dereferences to this reference. |
| 2298 | <span class="emphasis"><em><a href="#def_HEAD">HEAD</a></em></span> is a prime example of a symref. Symbolic |
| 2299 | references are manipulated with the <a href="git-symbolic-ref.html" target="_top">git-symbolic-ref(1)</a> |
| 2300 | command. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2301 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2302 | <a name="def_tag"></a>tag |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2303 | </span></dt><dd> |
| Junio C Hamano | 3646098 | 2007-05-27 04:29:12 | [diff] [blame] | 2304 | A <a href="#def_ref">ref</a> pointing to a <a href="#def_tag_object">tag</a> or |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2305 | <a href="#def_commit_object">commit object</a>. In contrast to a <a href="#def_head">head</a>, |
| 2306 | a tag is not changed by a <a href="#def_commit">commit</a>. Tags (not |
| 2307 | <a href="#def_tag_object">tag objects</a>) are stored in <code class="literal">$GIT_DIR/refs/tags/</code>. A |
| 2308 | git tag has nothing to do with a Lisp tag (which would be |
| 2309 | called an <a href="#def_object_type">object type</a> in git's context). A |
| 2310 | tag is most typically used to mark a particular point in the |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2311 | commit ancestry <a href="#def_chain">chain</a>. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2312 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2313 | <a name="def_tag_object"></a>tag object |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2314 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2315 | An <a href="#def_object">object</a> containing a <a href="#def_ref">ref</a> pointing to |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2316 | another object, which can contain a message just like a |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2317 | <a href="#def_commit_object">commit object</a>. It can also contain a (PGP) |
| Junio C Hamano | 3646098 | 2007-05-27 04:29:12 | [diff] [blame] | 2318 | signature, in which case it is called a "signed tag object". |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2319 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2320 | <a name="def_topic_branch"></a>topic branch |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2321 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2322 | A regular git <a href="#def_branch">branch</a> that is used by a developer to |
| 2323 | identify a conceptual line of development. Since branches are very easy |
| 2324 | and inexpensive, it is often desirable to have several small branches |
| 2325 | that each contain very well defined concepts or small incremental yet |
| 2326 | related changes. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2327 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2328 | <a name="def_tracking_branch"></a>tracking branch |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2329 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2330 | A regular git <a href="#def_branch">branch</a> that is used to follow changes from |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2331 | another <a href="#def_repository">repository</a>. A tracking |
| 2332 | branch should not contain direct modifications or have local commits |
| 2333 | made to it. A tracking branch can usually be |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2334 | identified as the right-hand-side <a href="#def_ref">ref</a> in a Pull: |
| 2335 | <a href="#def_refspec">refspec</a>. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2336 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2337 | <a name="def_tree"></a>tree |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2338 | </span></dt><dd> |
| Junio C Hamano | 3646098 | 2007-05-27 04:29:12 | [diff] [blame] | 2339 | Either a <a href="#def_working_tree">working tree</a>, or a <a href="#def_tree_object">tree object</a> together with the dependent <a href="#def_blob_object">blob</a> and tree objects |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2340 | (i.e. a stored representation of a working tree). |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2341 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2342 | <a name="def_tree_object"></a>tree object |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2343 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2344 | An <a href="#def_object">object</a> containing a list of file names and modes along |
| 2345 | with refs to the associated blob and/or tree objects. A |
| 2346 | <a href="#def_tree">tree</a> is equivalent to a <a href="#def_directory">directory</a>. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2347 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2348 | <a name="def_tree-ish"></a>tree-ish |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2349 | </span></dt><dd> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2350 | A <a href="#def_ref">ref</a> pointing to either a <a href="#def_commit_object">commit object</a>, a <a href="#def_tree_object">tree object</a>, or a <a href="#def_tag_object">tag object</a> pointing to a tag or commit or tree object. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2351 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2352 | <a name="def_unmerged_index"></a>unmerged index |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2353 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2354 | An <a href="#def_index">index</a> which contains unmerged |
| 2355 | <a href="#def_index_entry">index entries</a>. |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2356 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2357 | <a name="def_unreachable_object"></a>unreachable object |
| Junio C Hamano | aa83a7d | 2007-03-05 02:37:29 | [diff] [blame] | 2358 | </span></dt><dd> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2359 | An <a href="#def_object">object</a> which is not <a href="#def_reachable">reachable</a> from a |
| 2360 | <a href="#def_branch">branch</a>, <a href="#def_tag">tag</a>, or any other reference. |
| Junio C Hamano | aa83a7d | 2007-03-05 02:37:29 | [diff] [blame] | 2361 | </dd><dt><span class="term"> |
| Junio C Hamano | 3d5b41f | 2007-03-26 02:33:41 | [diff] [blame] | 2362 | <a name="def_working_tree"></a>working tree |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2363 | </span></dt><dd> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2364 | The tree of actual checked out files. The working tree is |
| 2365 | normally equal to the <a href="#def_HEAD">HEAD</a> plus any local changes |
| 2366 | that you have made but not yet committed. |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 2367 | </dd></dl></div></div><div class="appendix" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="git-quick-start"></a>Appendix A. Git Quick Reference</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="section"><a href="#quick-creating-a-new-repository">Creating a new repository</a></span></dt><dt><span class="section"><a href="#managing-branches">Managing branches</a></span></dt><dt><span class="section"><a href="#exploring-history">Exploring history</a></span></dt><dt><span class="section"><a href="#making-changes">Making changes</a></span></dt><dt><span class="section"><a href="#merging">Merging</a></span></dt><dt><span class="section"><a href="#sharing-your-changes">Sharing your changes</a></span></dt><dt><span class="section"><a href="#repository-maintenance">Repository maintenance</a></span></dt></dl></div><p>This is a quick summary of the major commands; the previous chapters |
| 2368 | explain how these work in more detail.</p><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="quick-creating-a-new-repository"></a>Creating a new repository</h2></div></div></div><p>From a tarball:</p><div class="literallayout"><p>$ tar xzf project.tar.gz<br> |
| 2369 | $ cd project<br> |
| 2370 | $ git init<br> |
| 2371 | Initialized empty Git repository in .git/<br> |
| 2372 | $ git add .<br> |
| 2373 | $ git commit</p></div><p>From a remote repository:</p><div class="literallayout"><p>$ git clone git://example.com/pub/project.git<br> |
| 2374 | $ cd project</p></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="managing-branches"></a>Managing branches</h2></div></div></div><div class="literallayout"><p>$ git branch # list all local branches in this repo<br> |
| 2375 | $ git checkout test # switch working directory to branch "test"<br> |
| 2376 | $ git branch new # create branch "new" starting at current HEAD<br> |
| Junio C Hamano | 764a667 | 2007-10-23 01:23:31 | [diff] [blame] | 2377 | $ git branch -d new # delete branch "new"</p></div><p>Instead of basing a new branch on current HEAD (the default), use:</p><div class="literallayout"><p>$ git branch new test # branch named "test"<br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 2378 | $ git branch new v2.6.15 # tag named v2.6.15<br> |
| 2379 | $ git branch new HEAD^ # commit before the most recent<br> |
| 2380 | $ git branch new HEAD^^ # commit before that<br> |
| 2381 | $ git branch new test~10 # ten commits before tip of branch "test"</p></div><p>Create and switch to a new branch at the same time:</p><div class="literallayout"><p>$ git checkout -b new v2.6.15</p></div><p>Update and examine branches from the repository you cloned from:</p><div class="literallayout"><p>$ git fetch # update<br> |
| 2382 | $ git branch -r # list<br> |
| 2383 | origin/master<br> |
| 2384 | origin/next<br> |
| 2385 | ...<br> |
| 2386 | $ git checkout -b masterwork origin/master</p></div><p>Fetch a branch from a different repository, and give it a new |
| 2387 | name in your repository:</p><div class="literallayout"><p>$ git fetch git://example.com/project.git theirbranch:mybranch<br> |
| 2388 | $ git fetch git://example.com/project.git v2.6.15:mybranch</p></div><p>Keep a list of repositories you work with regularly:</p><div class="literallayout"><p>$ git remote add example git://example.com/project.git<br> |
| 2389 | $ git remote # list remote repositories<br> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2390 | example<br> |
| 2391 | origin<br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 2392 | $ git remote show example # get details<br> |
| 2393 | * remote example<br> |
| 2394 | URL: git://example.com/project.git<br> |
| 2395 | Tracked remote branches<br> |
| 2396 | master next ...<br> |
| 2397 | $ git fetch example # update branches from example<br> |
| 2398 | $ git branch -r # list all remote branches</p></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="exploring-history"></a>Exploring history</h2></div></div></div><div class="literallayout"><p>$ gitk # visualize and browse history<br> |
| 2399 | $ git log # list all commits<br> |
| 2400 | $ git log src/ # ...modifying src/<br> |
| 2401 | $ git log v2.6.15..v2.6.16 # ...in v2.6.16, not in v2.6.15<br> |
| 2402 | $ git log master..test # ...in branch test, not in branch master<br> |
| 2403 | $ git log test..master # ...in branch master, but not in test<br> |
| 2404 | $ git log test...master # ...in one branch, not in both<br> |
| 2405 | $ git log -S'foo()' # ...where difference contain "foo()"<br> |
| 2406 | $ git log --since="2 weeks ago"<br> |
| 2407 | $ git log -p # show patches as well<br> |
| 2408 | $ git show # most recent commit<br> |
| 2409 | $ git diff v2.6.15..v2.6.16 # diff between two tagged versions<br> |
| 2410 | $ git diff v2.6.15..HEAD # diff with current head<br> |
| 2411 | $ git grep "foo()" # search working directory for "foo()"<br> |
| 2412 | $ git grep v2.6.15 "foo()" # search old tree for "foo()"<br> |
| 2413 | $ git show v2.6.15:a.txt # look at old version of a.txt</p></div><p>Search for regressions:</p><div class="literallayout"><p>$ git bisect start<br> |
| 2414 | $ git bisect bad # current version is bad<br> |
| 2415 | $ git bisect good v2.6.13-rc2 # last known good revision<br> |
| 2416 | Bisecting: 675 revisions left to test after this<br> |
| 2417 | # test here, then:<br> |
| 2418 | $ git bisect good # if this revision is good, or<br> |
| 2419 | $ git bisect bad # if this revision is bad.<br> |
| 2420 | # repeat until done.</p></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="making-changes"></a>Making changes</h2></div></div></div><p>Make sure git knows who to blame:</p><div class="literallayout"><p>$ cat >>~/.gitconfig <<\EOF<br> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2421 | [user]<br> |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 2422 | name = Your Name Comes Here<br> |
| 2423 | email = you@yourdomain.example.com<br> |
| Junio C Hamano | 75485c8 | 2007-05-19 04:20:33 | [diff] [blame] | 2424 | EOF</p></div><p>Select file contents to include in the next commit, then make the |
| Junio C Hamano | cc13f55 | 2007-07-24 08:59:43 | [diff] [blame] | 2425 | commit:</p><div class="literallayout"><p>$ git add a.txt # updated file<br> |
| 2426 | $ git add b.txt # new file<br> |
| 2427 | $ git rm c.txt # old file<br> |
| 2428 | $ git commit</p></div><p>Or, prepare and create the commit in one step:</p><div class="literallayout"><p>$ git commit d.txt # use latest content only of d.txt<br> |
| 2429 | $ git commit -a # use latest content of all tracked files</p></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="merging"></a>Merging</h2></div></div></div><div class="literallayout"><p>$ git merge test # merge branch "test" into the current branch<br> |
| 2430 | $ git pull git://example.com/project.git master<br> |
| 2431 | # fetch and merge in remote branch<br> |
| 2432 | $ git pull . test # equivalent to git merge test</p></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="sharing-your-changes"></a>Sharing your changes</h2></div></div></div><p>Importing or exporting patches:</p><div class="literallayout"><p>$ git format-patch origin..HEAD # format a patch for each commit<br> |
| 2433 | # in HEAD but not in origin<br> |
| 2434 | $ git am mbox # import patches from the mailbox "mbox"</p></div><p>Fetch a branch in a different git repository, then merge into the |
| 2435 | current branch:</p><div class="literallayout"><p>$ git pull git://example.com/project.git theirbranch</p></div><p>Store the fetched branch into a local branch before merging into the |
| 2436 | current branch:</p><div class="literallayout"><p>$ git pull git://example.com/project.git theirbranch:mybranch</p></div><p>After creating commits on a local branch, update the remote |
| 2437 | branch with your commits:</p><div class="literallayout"><p>$ git push ssh://example.com/project.git mybranch:theirbranch</p></div><p>When remote and local branch are both named "test":</p><div class="literallayout"><p>$ git push ssh://example.com/project.git test</p></div><p>Shortcut version for a frequently used remote repository:</p><div class="literallayout"><p>$ git remote add example ssh://example.com/project.git<br> |
| Junio C Hamano | 597ffcf | 2007-09-17 17:33:15 | [diff] [blame] | 2438 | $ git push example test</p></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="repository-maintenance"></a>Repository maintenance</h2></div></div></div><p>Check for corruption:</p><div class="literallayout"><p>$ git fsck</p></div><p>Recompress, remove unused cruft:</p><div class="literallayout"><p>$ git gc</p></div></div></div><div class="appendix" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="todo"></a>Appendix B. Notes and todo list for this manual</h2></div></div></div><p>This is a work in progress.</p><p>The basic requirements:</p><div class="itemizedlist"><ul type="disc"><li> |
| 2439 | It must be readable in order, from beginning to end, by someone |
| 2440 | intelligent with a basic grasp of the UNIX command line, but without |
| 2441 | any special knowledge of git. If necessary, any other prerequisites |
| 2442 | should be specifically mentioned as they arise. |
| 2443 | </li><li> |
| 2444 | Whenever possible, section headings should clearly describe the task |
| 2445 | they explain how to do, in language that requires no more knowledge |
| 2446 | than necessary: for example, "importing patches into a project" rather |
| 2447 | than "the git-am command" |
| 2448 | </li></ul></div><p>Think about how to create a clear chapter dependency graph that will |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2449 | allow people to get to important topics without necessarily reading |
| Junio C Hamano | 597ffcf | 2007-09-17 17:33:15 | [diff] [blame] | 2450 | everything in between.</p><p>Scan Documentation/ for other stuff left out; in particular:</p><div class="itemizedlist"><ul type="disc"><li> |
| 2451 | howto's |
| 2452 | </li><li> |
| 2453 | some of technical/? |
| 2454 | </li><li> |
| 2455 | hooks |
| 2456 | </li><li> |
| 2457 | list of commands in <a href="git.html" target="_top">git(1)</a> |
| 2458 | </li></ul></div><p>Scan email archives for other stuff left out</p><p>Scan man pages to see if any assume more background than this manual |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2459 | provides.</p><p>Simplify beginning by suggesting disconnected head instead of |
| Junio C Hamano | aa83a7d | 2007-03-05 02:37:29 | [diff] [blame] | 2460 | temporary branch creation?</p><p>Add more good examples. Entire sections of just cookbook examples |
| Junio C Hamano | 8f62db9 | 2007-02-01 00:22:22 | [diff] [blame] | 2461 | might be a good idea; maybe make an "advanced examples" section a |
| 2462 | standard end-of-chapter section?</p><p>Include cross-references to the glossary, where appropriate.</p><p>Document shallow clones? See draft 1.5.0 release notes for some |
| Junio C Hamano | ee1e428 | 2007-02-04 08:32:04 | [diff] [blame] | 2463 | documentation.</p><p>Add a section on working with other version control systems, including |
| Junio C Hamano | ce3650e | 2007-11-26 04:20:11 | [diff] [blame] | 2464 | CVS, Subversion, and just imports of series of release tarballs.</p><p>More details on gitweb?</p><p>Write a chapter on using plumbing and writing scripts.</p><p>Alternates, clone -reference, etc.</p><p>More on recovery from repository corruption. See: |
| 2465 | http://marc.theaimsgroup.com/?l=git&m=117263864820799&w=2 |
| 2466 | http://marc.theaimsgroup.com/?l=git&m=117147855503798&w=2 |
| 2467 | http://marc.theaimsgroup.com/?l=git&m=117147855503798&w=2</p></div></div></body></html> |
