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Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]258<title>A tutorial introduction to git</title>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]259</head>
260<body>
261<div id="header">
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]262<h1>A tutorial introduction to git</h1>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]263</div>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]264<div id="preamble">
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]265<div class="sectionbody">
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]266<p>This tutorial explains how to import a new project into git, make
267changes to it, and share changes with other developers.</p>
268<p>First, note that you can get documentation for a command such as "git
269diff" with:</p>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]270<div class="listingblock">
271<div class="content">
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]272<pre><tt>$ man git-diff</tt></pre>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]273</div></div>
Junio C Hamanoedd2b0a2007-01-15 06:12:45[diff] [blame]274<p>It is a good idea to introduce yourself to git with your name and
275public email address before doing any operation. The easiest
276way to do so is:</p>
Junio C Hamano699660b2006-11-29 20:40:10[diff] [blame]277<div class="listingblock">
278<div class="content">
Junio C Hamanoedd2b0a2007-01-15 06:12:45[diff] [blame]279<pre><tt>$ git repo-config --global user.name "Your Name Comes Here"
280$ git repo-config --global user.email you@yourdomain.example.com</tt></pre>
Junio C Hamano699660b2006-11-29 20:40:10[diff] [blame]281</div></div>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]282</div>
283</div>
284<h2>Importing a new project</h2>
285<div class="sectionbody">
286<p>Assume you have a tarball project.tar.gz with your initial work. You
287can place it under git revision control as follows.</p>
288<div class="listingblock">
289<div class="content">
290<pre><tt>$ tar xzf project.tar.gz
291$ cd project
Junio C Hamanofc4d38c2007-01-08 06:53:32[diff] [blame]292$ git init</tt></pre>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]293</div></div>
294<p>Git will reply</p>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]295<div class="listingblock">
296<div class="content">
Junio C Hamano7d23f5e2006-12-16 07:44:04[diff] [blame]297<pre><tt>Initialized empty Git repository in .git/</tt></pre>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]298</div></div>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]299<p>You've now initialized the working directory&#8212;you may notice a new
300directory created, named ".git". Tell git that you want it to track
Junio C Hamano79770b62007-01-07 07:43:58[diff] [blame]301every file under the current directory (note the <em>.</em>) with:</p>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]302<div class="listingblock">
303<div class="content">
304<pre><tt>$ git add .</tt></pre>
305</div></div>
306<p>Finally,</p>
307<div class="listingblock">
308<div class="content">
Junio C Hamano699660b2006-11-29 20:40:10[diff] [blame]309<pre><tt>$ git commit</tt></pre>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]310</div></div>
311<p>will prompt you for a commit message, then record the current state
312of all the files to the repository.</p>
Junio C Hamano79770b62007-01-07 07:43:58[diff] [blame]313</div>
314<h2>Making changes</h2>
315<div class="sectionbody">
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]316<p>Try modifying some files, then run</p>
317<div class="listingblock">
318<div class="content">
319<pre><tt>$ git diff</tt></pre>
320</div></div>
Junio C Hamanoeb692952007-01-03 22:02:12[diff] [blame]321<p>to review your changes. When you're done, tell git that you
322want the updated contents of these files in the commit and then
323make a commit, like this:</p>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]324<div class="listingblock">
325<div class="content">
Junio C Hamano79770b62007-01-07 07:43:58[diff] [blame]326<pre><tt>$ git add file1 file2 file3
Junio C Hamanoeb692952007-01-03 22:02:12[diff] [blame]327$ git commit</tt></pre>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]328</div></div>
Junio C Hamanoeb692952007-01-03 22:02:12[diff] [blame]329<p>This will again prompt your for a message describing the change, and then
Junio C Hamano79770b62007-01-07 07:43:58[diff] [blame]330record the new versions of the files you listed.</p>
331<p>Alternatively, instead of running <tt>git add</tt> beforehand, you can use</p>
Junio C Hamano699660b2006-11-29 20:40:10[diff] [blame]332<div class="listingblock">
333<div class="content">
334<pre><tt>$ git commit -a</tt></pre>
335</div></div>
Junio C Hamano79770b62007-01-07 07:43:58[diff] [blame]336<p>which will automatically notice modified (but not new) files.</p>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]337<p>A note on commit messages: Though not required, it's a good idea to
338begin the commit message with a single short (less than 50 character)
339line summarizing the change, followed by a blank line and then a more
340thorough description. Tools that turn commits into email, for
Junio C Hamanoeb692952007-01-03 22:02:12[diff] [blame]341example, use the first line on the Subject: line and the rest of the
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]342commit in the body.</p>
Junio C Hamanoe7935c42006-12-13 21:32:17[diff] [blame]343</div>
344<h2>Git tracks content not files</h2>
345<div class="sectionbody">
346<p>With git you have to explicitly "add" all the changed _content_ you
347want to commit together. This can be done in a few different ways:</p>
348<p>1) By using <em>git add &lt;file_spec&gt;&#8230;</em></p>
349<div class="literalblock">
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]350<div class="content">
Junio C Hamanoe7935c42006-12-13 21:32:17[diff] [blame]351<pre><tt>This can be performed multiple times before a commit. Note that this
352is not only for adding new files. Even modified files must be
353added to the set of changes about to be committed. The "git status"
354command gives you a summary of what is included so far for the
355next commit. When done you should use the 'git commit' command to
356make it real.</tt></pre>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]357</div></div>
Junio C Hamanoe7935c42006-12-13 21:32:17[diff] [blame]358<div class="literalblock">
359<div class="content">
360<pre><tt>Note: don't forget to 'add' a file again if you modified it after the
361first 'add' and before 'commit'. Otherwise only the previous added
362state of that file will be committed. This is because git tracks
363content, so what you're really 'add'ing to the commit is the *content*
364of the file in the state it is in when you 'add' it.</tt></pre>
365</div></div>
366<p>2) By using <em>git commit -a</em> directly</p>
367<div class="literalblock">
368<div class="content">
369<pre><tt>This is a quick way to automatically 'add' the content from all files
370that were modified since the previous commit, and perform the actual
371commit without having to separately 'add' them beforehand. This will
372not add content from new files i.e. files that were never added before.
373Those files still have to be added explicitly before performing a
374commit.</tt></pre>
375</div></div>
376<p>But here's a twist. If you do <em>git commit &lt;file1&gt; &lt;file2&gt; &#8230;</em> then only
377the changes belonging to those explicitly specified files will be
378committed, entirely bypassing the current "added" changes. Those "added"
379changes will still remain available for a subsequent commit though.</p>
380<p>However, for normal usage you only have to remember <em>git add</em> + <em>git commit</em>
381and/or <em>git commit -a</em>.</p>
382</div>
383<h2>Viewing the changelog</h2>
384<div class="sectionbody">
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]385<p>At any point you can view the history of your changes using</p>
386<div class="listingblock">
387<div class="content">
Junio C Hamano6f8a7902006-05-22 01:10:13[diff] [blame]388<pre><tt>$ git log</tt></pre>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]389</div></div>
390<p>If you also want to see complete diffs at each step, use</p>
391<div class="listingblock">
392<div class="content">
Junio C Hamano6f8a7902006-05-22 01:10:13[diff] [blame]393<pre><tt>$ git log -p</tt></pre>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]394</div></div>
Junio C Hamanoeb692952007-01-03 22:02:12[diff] [blame]395<p>Often the overview of the change is useful to get a feel of
396each step</p>
397<div class="listingblock">
398<div class="content">
399<pre><tt>$ git log --stat --summary</tt></pre>
400</div></div>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]401</div>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]402<h2>Managing branches</h2>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]403<div class="sectionbody">
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]404<p>A single git repository can maintain multiple branches of
405development. To create a new branch named "experimental", use</p>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]406<div class="listingblock">
407<div class="content">
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]408<pre><tt>$ git branch experimental</tt></pre>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]409</div></div>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]410<p>If you now run</p>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]411<div class="listingblock">
412<div class="content">
413<pre><tt>$ git branch</tt></pre>
414</div></div>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]415<p>you'll get a list of all existing branches:</p>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]416<div class="listingblock">
417<div class="content">
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]418<pre><tt> experimental
419* master</tt></pre>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]420</div></div>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]421<p>The "experimental" branch is the one you just created, and the
422"master" branch is a default branch that was created for you
423automatically. The asterisk marks the branch you are currently on;
424type</p>
425<div class="listingblock">
426<div class="content">
427<pre><tt>$ git checkout experimental</tt></pre>
428</div></div>
429<p>to switch to the experimental branch. Now edit a file, commit the
430change, and switch back to the master branch:</p>
431<div class="listingblock">
432<div class="content">
433<pre><tt>(edit file)
434$ git commit -a
435$ git checkout master</tt></pre>
436</div></div>
437<p>Check that the change you made is no longer visible, since it was
438made on the experimental branch and you're back on the master branch.</p>
439<p>You can make a different change on the master branch:</p>
440<div class="listingblock">
441<div class="content">
442<pre><tt>(edit file)
443$ git commit -a</tt></pre>
444</div></div>
445<p>at this point the two branches have diverged, with different changes
Junio C Hamano0df34342006-11-22 08:28:50[diff] [blame]446made in each. To merge the changes made in experimental into master, run</p>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]447<div class="listingblock">
448<div class="content">
Junio C Hamanoedd2b0a2007-01-15 06:12:45[diff] [blame]449<pre><tt>$ git merge experimental</tt></pre>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]450</div></div>
451<p>If the changes don't conflict, you're done. If there are conflicts,
452markers will be left in the problematic files showing the conflict;</p>
453<div class="listingblock">
454<div class="content">
455<pre><tt>$ git diff</tt></pre>
456</div></div>
457<p>will show this. Once you've edited the files to resolve the
458conflicts,</p>
459<div class="listingblock">
460<div class="content">
461<pre><tt>$ git commit -a</tt></pre>
462</div></div>
463<p>will commit the result of the merge. Finally,</p>
464<div class="listingblock">
465<div class="content">
466<pre><tt>$ gitk</tt></pre>
467</div></div>
468<p>will show a nice graphical representation of the resulting history.</p>
Junio C Hamanoeb692952007-01-03 22:02:12[diff] [blame]469<p>At this point you could delete the experimental branch with</p>
470<div class="listingblock">
471<div class="content">
472<pre><tt>$ git branch -d experimental</tt></pre>
473</div></div>
474<p>This command ensures that the changes in the experimental branch are
475already in the current branch.</p>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]476<p>If you develop on a branch crazy-idea, then regret it, you can always
477delete the branch with</p>
478<div class="listingblock">
479<div class="content">
480<pre><tt>$ git branch -D crazy-idea</tt></pre>
481</div></div>
482<p>Branches are cheap and easy, so this is a good way to try something
483out.</p>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]484</div>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]485<h2>Using git for collaboration</h2>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]486<div class="sectionbody">
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]487<p>Suppose that Alice has started a new project with a git repository in
488/home/alice/project, and that Bob, who has a home directory on the
489same machine, wants to contribute.</p>
490<p>Bob begins with:</p>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]491<div class="listingblock">
492<div class="content">
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]493<pre><tt>$ git clone /home/alice/project myrepo</tt></pre>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]494</div></div>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]495<p>This creates a new directory "myrepo" containing a clone of Alice's
496repository. The clone is on an equal footing with the original
Junio C Hamano341071d2006-06-04 07:24:48[diff] [blame]497project, possessing its own copy of the original project's history.</p>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]498<p>Bob then makes some changes and commits them:</p>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]499<div class="listingblock">
500<div class="content">
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]501<pre><tt>(edit files)
502$ git commit -a
503(repeat as necessary)</tt></pre>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]504</div></div>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]505<p>When he's ready, he tells Alice to pull changes from the repository
506at /home/bob/myrepo. She does this with:</p>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]507<div class="listingblock">
508<div class="content">
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]509<pre><tt>$ cd /home/alice/project
Junio C Hamanof98fd882006-11-26 07:28:29[diff] [blame]510$ git pull /home/bob/myrepo master</tt></pre>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]511</div></div>
Junio C Hamanof98fd882006-11-26 07:28:29[diff] [blame]512<p>This merges the changes from Bob's "master" branch into Alice's
513current branch. If Alice has made her own changes in the meantime,
514then she may need to manually fix any conflicts. (Note that the
515"master" argument in the above command is actually unnecessary, as it
516is the default.)</p>
517<p>The "pull" command thus performs two operations: it fetches changes
518from a remote branch, then merges them into the current branch.</p>
519<p>You can perform the first operation alone using the "git fetch"
520command. For example, Alice could create a temporary branch just to
521track Bob's changes, without merging them with her own, using:</p>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]522<div class="listingblock">
523<div class="content">
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]524<pre><tt>$ git fetch /home/bob/myrepo master:bob-incoming</tt></pre>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]525</div></div>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]526<p>which fetches the changes from Bob's master branch into a new branch
Junio C Hamanof98fd882006-11-26 07:28:29[diff] [blame]527named bob-incoming. Then</p>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]528<div class="listingblock">
529<div class="content">
Junio C Hamano6f8a7902006-05-22 01:10:13[diff] [blame]530<pre><tt>$ git log -p master..bob-incoming</tt></pre>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]531</div></div>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]532<p>shows a list of all the changes that Bob made since he branched from
533Alice's master branch.</p>
Junio C Hamanof98fd882006-11-26 07:28:29[diff] [blame]534<p>After examining those changes, and possibly fixing things, Alice
Junio C Hamanoedd2b0a2007-01-15 06:12:45[diff] [blame]535could merge the changes into her master branch:</p>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]536<div class="listingblock">
537<div class="content">
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]538<pre><tt>$ git checkout master
Junio C Hamanoedd2b0a2007-01-15 06:12:45[diff] [blame]539$ git merge bob-incoming</tt></pre>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]540</div></div>
Junio C Hamanoedd2b0a2007-01-15 06:12:45[diff] [blame]541<p>The last command is a merge from the "bob-incoming" branch in Alice's
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]542own repository.</p>
Junio C Hamanof98fd882006-11-26 07:28:29[diff] [blame]543<p>Alice could also perform both steps at once with:</p>
544<div class="listingblock">
545<div class="content">
546<pre><tt>$ git pull /home/bob/myrepo master:bob-incoming</tt></pre>
547</div></div>
548<p>This is just like the "git pull /home/bob/myrepo master" that we saw
549before, except that it also stores the unmerged changes from bob's
550master branch in bob-incoming before merging them into Alice's
551current branch. Note that git pull always merges into the current
552branch, regardless of what else is given on the commandline.</p>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]553<p>Later, Bob can update his repo with Alice's latest changes using</p>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]554<div class="listingblock">
555<div class="content">
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]556<pre><tt>$ git pull</tt></pre>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]557</div></div>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]558<p>Note that he doesn't need to give the path to Alice's repository;
559when Bob cloned Alice's repository, git stored the location of her
Junio C Hamanod3361ad2007-01-01 03:20:24[diff] [blame]560repository in the repository configuration, and that location is
561used for pulls:</p>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]562<div class="listingblock">
563<div class="content">
Junio C Hamanod3361ad2007-01-01 03:20:24[diff] [blame]564<pre><tt>$ git repo-config --get remote.origin.url
565/home/bob/myrepo</tt></pre>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]566</div></div>
Junio C Hamanod3361ad2007-01-01 03:20:24[diff] [blame]567<p>(The complete configuration created by git-clone is visible using
568"git repo-config -l", and the <a href="git-repo-config.html">git-repo-config(1)</a> man page
569explains the meaning of each option.)</p>
570<p>Git also keeps a pristine copy of Alice's master branch under the
571name "origin/master":</p>
572<div class="listingblock">
573<div class="content">
574<pre><tt>$ git branch -r
575 origin/master</tt></pre>
576</div></div>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]577<p>If Bob later decides to work from a different host, he can still
578perform clones and pulls using the ssh protocol:</p>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]579<div class="listingblock">
580<div class="content">
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]581<pre><tt>$ git clone alice.org:/home/alice/project myrepo</tt></pre>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]582</div></div>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]583<p>Alternatively, git has a native protocol, or can use rsync or http;
584see <a href="git-pull.html">git-pull(1)</a> for details.</p>
585<p>Git can also be used in a CVS-like mode, with a central repository
586that various users push changes to; see <a href="git-push.html">git-push(1)</a> and
587<a href="cvs-migration.html">git for CVS users</a>.</p>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]588</div>
Junio C Hamano6f8a7902006-05-22 01:10:13[diff] [blame]589<h2>Exploring history</h2>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]590<div class="sectionbody">
Junio C Hamano6f8a7902006-05-22 01:10:13[diff] [blame]591<p>Git history is represented as a series of interrelated commits. We
592have already seen that the git log command can list those commits.
593Note that first line of each git log entry also gives a name for the
594commit:</p>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]595<div class="listingblock">
596<div class="content">
Junio C Hamano6f8a7902006-05-22 01:10:13[diff] [blame]597<pre><tt>$ git log
598commit c82a22c39cbc32576f64f5c6b3f24b99ea8149c7
599Author: Junio C Hamano &lt;junkio@cox.net&gt;
600Date: Tue May 16 17:18:22 2006 -0700
601
602 merge-base: Clarify the comments on post processing.</tt></pre>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]603</div></div>
Junio C Hamano6f8a7902006-05-22 01:10:13[diff] [blame]604<p>We can give this name to git show to see the details about this
605commit.</p>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]606<div class="listingblock">
607<div class="content">
Junio C Hamano6f8a7902006-05-22 01:10:13[diff] [blame]608<pre><tt>$ git show c82a22c39cbc32576f64f5c6b3f24b99ea8149c7</tt></pre>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]609</div></div>
Junio C Hamanoeb692952007-01-03 22:02:12[diff] [blame]610<p>But there are other ways to refer to commits. You can use any initial
Junio C Hamano6f8a7902006-05-22 01:10:13[diff] [blame]611part of the name that is long enough to uniquely identify the commit:</p>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]612<div class="listingblock">
613<div class="content">
Junio C Hamano6f8a7902006-05-22 01:10:13[diff] [blame]614<pre><tt>$ git show c82a22c39c # the first few characters of the name are
615 # usually enough
616$ git show HEAD # the tip of the current branch
617$ git show experimental # the tip of the "experimental" branch</tt></pre>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]618</div></div>
Junio C Hamanoeb692952007-01-03 22:02:12[diff] [blame]619<p>Every commit usually has one "parent" commit
620which points to the previous state of the project:</p>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]621<div class="listingblock">
622<div class="content">
Junio C Hamano6f8a7902006-05-22 01:10:13[diff] [blame]623<pre><tt>$ git show HEAD^ # to see the parent of HEAD
624$ git show HEAD^^ # to see the grandparent of HEAD
625$ git show HEAD~4 # to see the great-great grandparent of HEAD</tt></pre>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]626</div></div>
Junio C Hamano6f8a7902006-05-22 01:10:13[diff] [blame]627<p>Note that merge commits may have more than one parent:</p>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]628<div class="listingblock">
629<div class="content">
Junio C Hamano6f8a7902006-05-22 01:10:13[diff] [blame]630<pre><tt>$ git show HEAD^1 # show the first parent of HEAD (same as HEAD^)
631$ git show HEAD^2 # show the second parent of HEAD</tt></pre>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]632</div></div>
Junio C Hamano6f8a7902006-05-22 01:10:13[diff] [blame]633<p>You can also give commits names of your own; after running</p>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]634<div class="listingblock">
635<div class="content">
Junio C Hamano6f8a7902006-05-22 01:10:13[diff] [blame]636<pre><tt>$ git-tag v2.5 1b2e1d63ff</tt></pre>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]637</div></div>
Junio C Hamano6f8a7902006-05-22 01:10:13[diff] [blame]638<p>you can refer to 1b2e1d63ff by the name "v2.5". If you intend to
639share this name with other people (for example, to identify a release
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]640version), you should create a "tag" object, and perhaps sign it; see
641<a href="git-tag.html">git-tag(1)</a> for details.</p>
Junio C Hamano6f8a7902006-05-22 01:10:13[diff] [blame]642<p>Any git command that needs to know a commit can take any of these
643names. For example:</p>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]644<div class="listingblock">
645<div class="content">
Junio C Hamano6f8a7902006-05-22 01:10:13[diff] [blame]646<pre><tt>$ git diff v2.5 HEAD # compare the current HEAD to v2.5
647$ git branch stable v2.5 # start a new branch named "stable" based
648 # at v2.5
649$ git reset --hard HEAD^ # reset your current branch and working
Junio C Hamano33db4372006-06-07 19:51:45[diff] [blame]650 # directory to its state at HEAD^</tt></pre>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]651</div></div>
Junio C Hamano6f8a7902006-05-22 01:10:13[diff] [blame]652<p>Be careful with that last command: in addition to losing any changes
653in the working directory, it will also remove all later commits from
654this branch. If this branch is the only branch containing those
655commits, they will be lost. (Also, don't use "git reset" on a
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]656publicly-visible branch that other developers pull from, as git will
Junio C Hamano6f8a7902006-05-22 01:10:13[diff] [blame]657be confused by history that disappears in this way.)</p>
658<p>The git grep command can search for strings in any version of your
659project, so</p>
660<div class="listingblock">
661<div class="content">
662<pre><tt>$ git grep "hello" v2.5</tt></pre>
663</div></div>
Junio C Hamano341071d2006-06-04 07:24:48[diff] [blame]664<p>searches for all occurrences of "hello" in v2.5.</p>
Junio C Hamano6f8a7902006-05-22 01:10:13[diff] [blame]665<p>If you leave out the commit name, git grep will search any of the
666files it manages in your current directory. So</p>
667<div class="listingblock">
668<div class="content">
669<pre><tt>$ git grep "hello"</tt></pre>
670</div></div>
671<p>is a quick way to search just the files that are tracked by git.</p>
672<p>Many git commands also take sets of commits, which can be specified
673in a number of ways. Here are some examples with git log:</p>
674<div class="listingblock">
675<div class="content">
676<pre><tt>$ git log v2.5..v2.6 # commits between v2.5 and v2.6
677$ git log v2.5.. # commits since v2.5
678$ git log --since="2 weeks ago" # commits from the last 2 weeks
679$ git log v2.5.. Makefile # commits since v2.5 which modify
680 # Makefile</tt></pre>
681</div></div>
682<p>You can also give git log a "range" of commits where the first is not
683necessarily an ancestor of the second; for example, if the tips of
684the branches "stable-release" and "master" diverged from a common
685commit some time ago, then</p>
686<div class="listingblock">
687<div class="content">
688<pre><tt>$ git log stable..experimental</tt></pre>
689</div></div>
690<p>will list commits made in the experimental branch but not in the
691stable branch, while</p>
692<div class="listingblock">
693<div class="content">
694<pre><tt>$ git log experimental..stable</tt></pre>
695</div></div>
696<p>will show the list of commits made on the stable branch but not
697the experimental branch.</p>
698<p>The "git log" command has a weakness: it must present commits in a
699list. When the history has lines of development that diverged and
700then merged back together, the order in which "git log" presents
701those commits is meaningless.</p>
702<p>Most projects with multiple contributors (such as the linux kernel,
703or git itself) have frequent merges, and gitk does a better job of
704visualizing their history. For example,</p>
705<div class="listingblock">
706<div class="content">
707<pre><tt>$ gitk --since="2 weeks ago" drivers/</tt></pre>
708</div></div>
709<p>allows you to browse any commits from the last 2 weeks of commits
Junio C Hamanobb8fb052006-05-30 07:21:12[diff] [blame]710that modified files under the "drivers" directory. (Note: you can
711adjust gitk's fonts by holding down the control key while pressing
712"-" or "+".)</p>
Junio C Hamano6f8a7902006-05-22 01:10:13[diff] [blame]713<p>Finally, most commands that take filenames will optionally allow you
714to precede any filename by a commit, to specify a particular version
Junio C Hamanobb8fb052006-05-30 07:21:12[diff] [blame]715of the file:</p>
Junio C Hamano6f8a7902006-05-22 01:10:13[diff] [blame]716<div class="listingblock">
717<div class="content">
718<pre><tt>$ git diff v2.5:Makefile HEAD:Makefile.in</tt></pre>
719</div></div>
Junio C Hamanoeb692952007-01-03 22:02:12[diff] [blame]720<p>You can also use "git show" to see any such file:</p>
Junio C Hamanobb8fb052006-05-30 07:21:12[diff] [blame]721<div class="listingblock">
722<div class="content">
Junio C Hamanoeb692952007-01-03 22:02:12[diff] [blame]723<pre><tt>$ git show v2.5:Makefile</tt></pre>
Junio C Hamanobb8fb052006-05-30 07:21:12[diff] [blame]724</div></div>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]725</div>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]726<h2>Next Steps</h2>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]727<div class="sectionbody">
Junio C Hamano6f8a7902006-05-22 01:10:13[diff] [blame]728<p>This tutorial should be enough to perform basic distributed revision
729control for your projects. However, to fully understand the depth
730and power of git you need to understand two simple ideas on which it
731is based:</p>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]732<ul>
733<li>
734<p>
Junio C Hamano6f8a7902006-05-22 01:10:13[diff] [blame]735The object database is the rather elegant system used to
736 store the history of your project&#8212;files, directories, and
737 commits.
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]738</p>
739</li>
740<li>
741<p>
Junio C Hamano6f8a7902006-05-22 01:10:13[diff] [blame]742The index file is a cache of the state of a directory tree,
743 used to create commits, check out working directories, and
744 hold the various trees involved in a merge.
745</p>
746</li>
747</ul>
748<p><a href="tutorial-2.html">Part two of this tutorial</a> explains the object
749database, the index file, and a few other odds and ends that you'll
750need to make the most of git.</p>
751<p>If you don't want to consider with that right away, a few other
752digressions that may be interesting at this point are:</p>
753<ul>
754<li>
755<p>
Junio C Hamanoc2b0a492006-01-23 07:54:36[diff] [blame]756<a href="git-format-patch.html">git-format-patch(1)</a>, <a href="git-am.html">git-am(1)</a>: These convert
757 series of git commits into emailed patches, and vice versa,
758 useful for projects such as the linux kernel which rely heavily
759 on emailed patches.
760</p>
761</li>
762<li>
763<p>
764<a href="git-bisect.html">git-bisect(1)</a>: When there is a regression in your
765 project, one way to track down the bug is by searching through
766 the history to find the exact commit that's to blame. Git bisect
767 can help you perform a binary search for that commit. It is
768 smart enough to perform a close-to-optimal search even in the
769 case of complex non-linear history with lots of merged branches.
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]770</p>
771</li>
Junio C Hamano6f8a7902006-05-22 01:10:13[diff] [blame]772<li>
773<p>
Junio C Hamano341071d2006-06-04 07:24:48[diff] [blame]774<a href="everyday.html">Everyday GIT with 20 Commands Or So</a>
Junio C Hamano6f8a7902006-05-22 01:10:13[diff] [blame]775</p>
776</li>
777<li>
778<p>
779<a href="cvs-migration.html">git for CVS users</a>.
780</p>
781</li>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]782</ul>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]783</div>
784<div id="footer">
785<div id="footer-text">
Junio C Hamanoedd2b0a2007-01-15 06:12:45[diff] [blame]786Last updated 15-Jan-2007 06:12:34 UTC
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]787</div>
788</div>
789</body>
790</html>