Google Git
Sign in
chromium / external / gitster / git-htmldocs / 0d3c81546c38713ca17817d884eed8f9ae6ae88b / . / git-diff-index.html
blob: b7581bbc0ce7dc0a3b157462fe0c6233c3a8eb91 [file] [log] [blame]
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<meta name="generator" content="AsciiDoc 7.0.2" />
<style type="text/css">
/* Debug borders */
p, li, dt, dd, div, pre, h1, h2, h3, h4, h5, h6 {
/*
border: 1px solid red;
*/
}
body {
margin: 1em 5% 1em 5%;
}
a { color: blue; }
a:visited { color: fuchsia; }
em {
font-style: italic;
}
strong {
font-weight: bold;
}
tt {
color: navy;
}
h1, h2, h3, h4, h5, h6 {
color: #527bbd;
font-family: sans-serif;
margin-top: 1.2em;
margin-bottom: 0.5em;
line-height: 1.3;
}
h1 {
border-bottom: 2px solid silver;
}
h2 {
border-bottom: 2px solid silver;
padding-top: 0.5em;
}
div.sectionbody {
font-family: serif;
margin-left: 0;
}
hr {
border: 1px solid silver;
}
p {
margin-top: 0.5em;
margin-bottom: 0.5em;
}
pre {
padding: 0;
margin: 0;
}
span#author {
color: #527bbd;
font-family: sans-serif;
font-weight: bold;
font-size: 1.2em;
}
span#email {
}
span#revision {
font-family: sans-serif;
}
div#footer {
font-family: sans-serif;
font-size: small;
border-top: 2px solid silver;
padding-top: 0.5em;
margin-top: 4.0em;
}
div#footer-text {
float: left;
padding-bottom: 0.5em;
}
div#footer-badges {
float: right;
padding-bottom: 0.5em;
}
div#preamble,
div.tableblock, div.imageblock, div.exampleblock, div.verseblock,
div.quoteblock, div.literalblock, div.listingblock, div.sidebarblock,
div.admonitionblock {
margin-right: 10%;
margin-top: 1.5em;
margin-bottom: 1.5em;
}
div.admonitionblock {
margin-top: 2.5em;
margin-bottom: 2.5em;
}
div.content { /* Block element content. */
padding: 0;
}
/* Block element titles. */
div.title, caption.title {
font-family: sans-serif;
font-weight: bold;
text-align: left;
margin-top: 1.0em;
margin-bottom: 0.5em;
}
div.title + * {
margin-top: 0;
}
td div.title:first-child {
margin-top: 0.0em;
}
div.content div.title:first-child {
margin-top: 0.0em;
}
div.content + div.title {
margin-top: 0.0em;
}
div.sidebarblock > div.content {
background: #ffffee;
border: 1px solid silver;
padding: 0.5em;
}
div.listingblock > div.content {
border: 1px solid silver;
background: #f4f4f4;
padding: 0.5em;
}
div.quoteblock > div.content {
padding-left: 2.0em;
}
div.quoteblock .attribution {
text-align: right;
}
div.admonitionblock .icon {
vertical-align: top;
font-size: 1.1em;
font-weight: bold;
text-decoration: underline;
color: #527bbd;
padding-right: 0.5em;
}
div.admonitionblock td.content {
padding-left: 0.5em;
border-left: 2px solid silver;
}
div.exampleblock > div.content {
border-left: 2px solid silver;
padding: 0.5em;
}
div.verseblock div.content {
white-space: pre;
}
div.imageblock div.content { padding-left: 0; }
div.imageblock img { border: 1px solid silver; }
span.image img { border-style: none; }
dl {
margin-top: 0.8em;
margin-bottom: 0.8em;
}
dt {
margin-top: 0.5em;
margin-bottom: 0;
font-style: italic;
}
dd > *:first-child {
margin-top: 0;
}
ul, ol {
list-style-position: outside;
}
ol.olist2 {
list-style-type: lower-alpha;
}
div.tableblock > table {
border-color: #527bbd;
border-width: 3px;
}
thead {
font-family: sans-serif;
font-weight: bold;
}
tfoot {
font-weight: bold;
}
div.hlist {
margin-top: 0.8em;
margin-bottom: 0.8em;
}
td.hlist1 {
vertical-align: top;
font-style: italic;
padding-right: 0.8em;
}
td.hlist2 {
vertical-align: top;
}
@media print {
div#footer-badges { display: none; }
}
include::./stylesheets/xhtml11-manpage.css[]
/* Workarounds for IE6's broken and incomplete CSS2. */
div.sidebar-content {
background: #ffffee;
border: 1px solid silver;
padding: 0.5em;
}
div.sidebar-title, div.image-title {
font-family: sans-serif;
font-weight: bold;
margin-top: 0.0em;
margin-bottom: 0.5em;
}
div.listingblock div.content {
border: 1px solid silver;
background: #f4f4f4;
padding: 0.5em;
}
div.quoteblock-content {
padding-left: 2.0em;
}
div.exampleblock-content {
border-left: 2px solid silver;
padding-left: 0.5em;
}
</style>
<title>git-diff-index(1)</title>
</head>
<body>
<div id="header">
<h1>
git-diff-index(1) Manual Page
</h1>
<h2>NAME</h2>
<div class="sectionbody">
<p>git-diff-index -
Compares content and mode of blobs between the index and repository
</p>
</div>
</div>
<h2>SYNOPSIS</h2>
<div class="sectionbody">
<p><em>git-diff-index</em> [-m] [--cached] [&lt;common diff options&gt;] &lt;tree-ish&gt; [&lt;path&gt;&#8230;]</p>
</div>
<h2>DESCRIPTION</h2>
<div class="sectionbody">
<p>Compares the content and mode of the blobs found via a tree
object with the content of the current index and, optionally
ignoring the stat state of the file on disk. When paths are
specified, compares only those named paths. Otherwise all
entries in the index are compared.</p>
</div>
<h2>OPTIONS</h2>
<div class="sectionbody">
<dl>
<dt>
-p
</dt>
<dd>
<p>
Generate patch (see section on generating patches)
</p>
</dd>
<dt>
-u
</dt>
<dd>
<p>
Synonym for "-p".
</p>
</dd>
<dt>
--raw
</dt>
<dd>
<p>
Generate the raw format.
</p>
</dd>
<dt>
--patch-with-raw
</dt>
<dd>
<p>
Synonym for "-p --raw".
</p>
</dd>
<dt>
--stat[=width[,name-width]]
</dt>
<dd>
<p>
Generate a diffstat. You can override the default
output width for 80-column terminal by "--stat=width".
The width of the filename part can be controlled by
giving another width to it separated by a comma.
</p>
</dd>
<dt>
--numstat
</dt>
<dd>
<p>
Similar to --stat, but shows number of added and
deleted lines in decimal notation and pathname without
abbreviation, to make it more machine friendly.
</p>
</dd>
<dt>
--summary
</dt>
<dd>
<p>
Output a condensed summary of extended header information
such as creations, renames and mode changes.
</p>
</dd>
<dt>
--patch-with-stat
</dt>
<dd>
<p>
Synonym for "-p --stat".
</p>
</dd>
<dt>
-z
</dt>
<dd>
<p>
\0 line termination on output
</p>
</dd>
<dt>
--name-only
</dt>
<dd>
<p>
Show only names of changed files.
</p>
</dd>
<dt>
--name-status
</dt>
<dd>
<p>
Show only names and status of changed files.
</p>
</dd>
<dt>
--color
</dt>
<dd>
<p>
Show colored diff.
</p>
</dd>
<dt>
--no-color
</dt>
<dd>
<p>
Turn off colored diff, even when the configuration file
gives the default to color output.
</p>
</dd>
<dt>
--color-words
</dt>
<dd>
<p>
Show colored word diff, i.e. color words which have changed.
</p>
</dd>
<dt>
--no-renames
</dt>
<dd>
<p>
Turn off rename detection, even when the configuration
file gives the default to do so.
</p>
</dd>
<dt>
--full-index
</dt>
<dd>
<p>
Instead of the first handful characters, show full
object name of pre- and post-image blob on the "index"
line when generating a patch format output.
</p>
</dd>
<dt>
--binary
</dt>
<dd>
<p>
In addition to --full-index, output "binary diff" that
can be applied with "git apply".
</p>
</dd>
<dt>
--abbrev[=&lt;n&gt;]
</dt>
<dd>
<p>
Instead of showing the full 40-byte hexadecimal object
name in diff-raw format output and diff-tree header
lines, show only handful hexdigits prefix. This is
independent of --full-index option above, which controls
the diff-patch output format. Non default number of
digits can be specified with --abbrev=&lt;n&gt;.
</p>
</dd>
<dt>
-B
</dt>
<dd>
<p>
Break complete rewrite changes into pairs of delete and create.
</p>
</dd>
<dt>
-M
</dt>
<dd>
<p>
Detect renames.
</p>
</dd>
<dt>
-C
</dt>
<dd>
<p>
Detect copies as well as renames.
</p>
</dd>
<dt>
--diff-filter=[ACDMRTUXB*]
</dt>
<dd>
<p>
Select only files that are Added (<tt>A</tt>), Copied (<tt>C</tt>),
Deleted (<tt>D</tt>), Modified (<tt>M</tt>), Renamed (<tt>R</tt>), have their
type (mode) changed (<tt>T</tt>), are Unmerged (<tt>U</tt>), are
Unknown (<tt>X</tt>), or have had their pairing Broken (<tt>B</tt>).
Any combination of the filter characters may be used.
When <tt>*</tt> (All-or-none) is added to the combination, all
paths are selected if there is any file that matches
other criteria in the comparison; if there is no file
that matches other criteria, nothing is selected.
</p>
</dd>
<dt>
--find-copies-harder
</dt>
<dd>
<p>
For performance reasons, by default, -C option finds copies only
if the original file of the copy was modified in the same
changeset. This flag makes the command
inspect unmodified files as candidates for the source of
copy. This is a very expensive operation for large
projects, so use it with caution.
</p>
</dd>
<dt>
-l&lt;num&gt;
</dt>
<dd>
<p>
-M and -C options require O(n^2) processing time where n
is the number of potential rename/copy targets. This
option prevents rename/copy detection from running if
the number of rename/copy targets exceeds the specified
number.
</p>
</dd>
<dt>
-S&lt;string&gt;
</dt>
<dd>
<p>
Look for differences that contain the change in &lt;string&gt;.
</p>
</dd>
<dt>
--pickaxe-all
</dt>
<dd>
<p>
When -S finds a change, show all the changes in that
changeset, not just the files that contain the change
in &lt;string&gt;.
</p>
</dd>
<dt>
--pickaxe-regex
</dt>
<dd>
<p>
Make the &lt;string&gt; not a plain string but an extended POSIX
regex to match.
</p>
</dd>
<dt>
-O&lt;orderfile&gt;
</dt>
<dd>
<p>
Output the patch in the order specified in the
&lt;orderfile&gt;, which has one shell glob pattern per line.
</p>
</dd>
<dt>
-R
</dt>
<dd>
<p>
Swap two inputs; that is, show differences from index or
on-disk file to tree contents.
</p>
</dd>
<dt>
--text
</dt>
<dd>
<p>
Treat all files as text.
</p>
</dd>
<dt>
-a
</dt>
<dd>
<p>
Shorthand for "--text".
</p>
</dd>
</dl>
<p>For more detailed explanation on these common options, see also
<a href="diffcore.html">diffcore documentation</a>.</p>
<dl>
<dt>
&lt;tree-ish&gt;
</dt>
<dd>
<p>
The id of a tree object to diff against.
</p>
</dd>
<dt>
--cached
</dt>
<dd>
<p>
do not consider the on-disk file at all
</p>
</dd>
<dt>
-m
</dt>
<dd>
<p>
By default, files recorded in the index but not checked
out are reported as deleted. This flag makes
"git-diff-index" say that all non-checked-out files are up
to date.
</p>
</dd>
</dl>
</div>
<h2>Output format</h2>
<div class="sectionbody">
<p>The output format from "git-diff-index", "git-diff-tree" and
"git-diff-files" are very similar.</p>
<p>These commands all compare two sets of things; what is
compared differs:</p>
<dl>
<dt>
git-diff-index &lt;tree-ish&gt;
</dt>
<dd>
<p>
compares the &lt;tree-ish&gt; and the files on the filesystem.
</p>
</dd>
<dt>
git-diff-index --cached &lt;tree-ish&gt;
</dt>
<dd>
<p>
compares the &lt;tree-ish&gt; and the index.
</p>
</dd>
<dt>
git-diff-tree [-r] &lt;tree-ish-1&gt; &lt;tree-ish-2&gt; [&lt;pattern&gt;&#8230;]
</dt>
<dd>
<p>
compares the trees named by the two arguments.
</p>
</dd>
<dt>
git-diff-files [&lt;pattern&gt;&#8230;]
</dt>
<dd>
<p>
compares the index and the files on the filesystem.
</p>
</dd>
</dl>
<p>An output line is formatted this way:</p>
<div class="listingblock">
<div class="content">
<pre><tt>in-place edit :100644 100644 bcd1234... 0123456... M file0
copy-edit :100644 100644 abcd123... 1234567... C68 file1 file2
rename-edit :100644 100644 abcd123... 1234567... R86 file1 file3
create :000000 100644 0000000... 1234567... A file4
delete :100644 000000 1234567... 0000000... D file5
unmerged :000000 000000 0000000... 0000000... U file6</tt></pre>
</div></div>
<p>That is, from the left to the right:</p>
<ol>
<li>
<p>
a colon.
</p>
</li>
<li>
<p>
mode for "src"; 000000 if creation or unmerged.
</p>
</li>
<li>
<p>
a space.
</p>
</li>
<li>
<p>
mode for "dst"; 000000 if deletion or unmerged.
</p>
</li>
<li>
<p>
a space.
</p>
</li>
<li>
<p>
sha1 for "src"; 0{40} if creation or unmerged.
</p>
</li>
<li>
<p>
a space.
</p>
</li>
<li>
<p>
sha1 for "dst"; 0{40} if creation, unmerged or "look at work tree".
</p>
</li>
<li>
<p>
a space.
</p>
</li>
<li>
<p>
status, followed by optional "score" number.
</p>
</li>
<li>
<p>
a tab or a NUL when <em>-z</em> option is used.
</p>
</li>
<li>
<p>
path for "src"
</p>
</li>
<li>
<p>
a tab or a NUL when <em>-z</em> option is used; only exists for C or R.
</p>
</li>
<li>
<p>
path for "dst"; only exists for C or R.
</p>
</li>
<li>
<p>
an LF or a NUL when <em>-z</em> option is used, to terminate the record.
</p>
</li>
</ol>
<p>&lt;sha1&gt; is shown as all 0's if a file is new on the filesystem
and it is out of sync with the index.</p>
<p>Example:</p>
<div class="listingblock">
<div class="content">
<pre><tt>:100644 100644 5be4a4...... 000000...... M file.c</tt></pre>
</div></div>
<p>When <tt>-z</tt> option is not used, TAB, LF, and backslash characters
in pathnames are represented as <tt>\t</tt>, <tt>\n</tt>, and <tt>\\</tt>,
respectively.</p>
</div>
<h2>Generating patches with -p</h2>
<div class="sectionbody">
<p>When "git-diff-index", "git-diff-tree", or "git-diff-files" are run
with a <em>-p</em> option, they do not produce the output described above;
instead they produce a patch file.</p>
<p>The patch generation can be customized at two levels.</p>
<ol>
<li>
<p>
When the environment variable <em>GIT_EXTERNAL_DIFF</em> is not set,
these commands internally invoke "diff" like this:
</p>
<div class="literalblock">
<div class="content">
<pre><tt>diff -L a/&lt;path&gt; -L b/&lt;path&gt; -pu &lt;old&gt; &lt;new&gt;</tt></pre>
</div></div>
<p>For added files, <tt>/dev/null</tt> is used for &lt;old&gt;. For removed
files, <tt>/dev/null</tt> is used for &lt;new&gt;</p>
<p>The "diff" formatting options can be customized via the
environment variable <em>GIT_DIFF_OPTS</em>. For example, if you
prefer context diff:</p>
<div class="literalblock">
<div class="content">
<pre><tt>GIT_DIFF_OPTS=-c git-diff-index -p HEAD</tt></pre>
</div></div>
</li>
<li>
<p>
When the environment variable <em>GIT_EXTERNAL_DIFF</em> is set, the
program named by it is called, instead of the diff invocation
described above.
</p>
<p>For a path that is added, removed, or modified,
<em>GIT_EXTERNAL_DIFF</em> is called with 7 parameters:</p>
<div class="literalblock">
<div class="content">
<pre><tt>path old-file old-hex old-mode new-file new-hex new-mode</tt></pre>
</div></div>
<p>where:</p>
<div class="hlist"><table>
<tr>
<td class="hlist1">
&lt;old|new&gt;-file
</td>
<td class="hlist2">
are files GIT_EXTERNAL_DIFF can use to read the
contents of &lt;old|new&gt;,
</td>
</tr>
<tr>
<td class="hlist1">
&lt;old|new&gt;-hex
</td>
<td class="hlist2">
are the 40-hexdigit SHA1 hashes,
</td>
</tr>
<tr>
<td class="hlist1">
&lt;old|new&gt;-mode
</td>
<td class="hlist2">
are the octal representation of the file modes.
</td>
</tr>
</table></div>
<p>The file parameters can point at the user's working file
(e.g. <tt>new-file</tt> in "git-diff-files"), <tt>/dev/null</tt> (e.g. <tt>old-file</tt>
when a new file is added), or a temporary file (e.g. <tt>old-file</tt> in the
index). <em>GIT_EXTERNAL_DIFF</em> should not worry about unlinking the
temporary file --- it is removed when <em>GIT_EXTERNAL_DIFF</em> exits.</p>
</li>
</ol>
<p>For a path that is unmerged, <em>GIT_EXTERNAL_DIFF</em> is called with 1
parameter, &lt;path&gt;.</p>
</div>
<h2>git specific extension to diff format</h2>
<div class="sectionbody">
<p>What -p option produces is slightly different from the
traditional diff format.</p>
<ol>
<li>
<p>
It is preceded with a "git diff" header, that looks like
this:
</p>
<div class="literalblock">
<div class="content">
<pre><tt>diff --git a/file1 b/file2</tt></pre>
</div></div>
<p>The <tt>a/</tt> and <tt>b/</tt> filenames are the same unless rename/copy is
involved. Especially, even for a creation or a deletion,
<tt>/dev/null</tt> is _not_ used in place of <tt>a/</tt> or <tt>b/</tt> filenames.</p>
<p>When rename/copy is involved, <tt>file1</tt> and <tt>file2</tt> show the
name of the source file of the rename/copy and the name of
the file that rename/copy produces, respectively.</p>
</li>
<li>
<p>
It is followed by one or more extended header lines:
</p>
<div class="literalblock">
<div class="content">
<pre><tt>old mode &lt;mode&gt;
new mode &lt;mode&gt;
deleted file mode &lt;mode&gt;
new file mode &lt;mode&gt;
copy from &lt;path&gt;
copy to &lt;path&gt;
rename from &lt;path&gt;
rename to &lt;path&gt;
similarity index &lt;number&gt;
dissimilarity index &lt;number&gt;
index &lt;hash&gt;..&lt;hash&gt; &lt;mode&gt;</tt></pre>
</div></div>
</li>
<li>
<p>
TAB, LF, double quote and backslash characters in pathnames
are represented as <tt>\t</tt>, <tt>\n</tt>, <tt>\"</tt> and <tt>\\</tt>, respectively.
If there is need for such substitution then the whole
pathname is put in double quotes.
</p>
</li>
</ol>
</div>
<h2>combined diff format</h2>
<div class="sectionbody">
<p>git-diff-tree and git-diff-files can take <em>-c</em> or <em>--cc</em> option
to produce <em>combined diff</em>, which looks like this:</p>
<div class="listingblock">
<div class="content">
<pre><tt>diff --combined describe.c
index fabadb8,cc95eb0..4866510
--- a/describe.c
+++ b/describe.c
@@@ -98,20 -98,12 +98,20 @@@
return (a_date &gt; b_date) ? -1 : (a_date == b_date) ? 0 : 1;
}
- static void describe(char *arg)
-static void describe(struct commit *cmit, int last_one)
++static void describe(char *arg, int last_one)
{
+ unsigned char sha1[20];
+ struct commit *cmit;
struct commit_list *list;
static int initialized = 0;
struct commit_name *n;
+ if (get_sha1(arg, sha1) &lt; 0)
+ usage(describe_usage);
+ cmit = lookup_commit_reference(sha1);
+ if (!cmit)
+ usage(describe_usage);
+
if (!initialized) {
initialized = 1;
for_each_ref(get_name);</tt></pre>
</div></div>
<ol>
<li>
<p>
It is preceded with a "git diff" header, that looks like
this (when <em>-c</em> option is used):
</p>
<div class="literalblock">
<div class="content">
<pre><tt>diff --combined file</tt></pre>
</div></div>
<p>or like this (when <em>--cc</em> option is used):</p>
<div class="literalblock">
<div class="content">
<pre><tt>diff --c file</tt></pre>
</div></div>
</li>
<li>
<p>
It is followed by one or more extended header lines
(this example shows a merge with two parents):
</p>
<div class="literalblock">
<div class="content">
<pre><tt>index &lt;hash&gt;,&lt;hash&gt;..&lt;hash&gt;
mode &lt;mode&gt;,&lt;mode&gt;..&lt;mode&gt;
new file mode &lt;mode&gt;
deleted file mode &lt;mode&gt;,&lt;mode&gt;</tt></pre>
</div></div>
<p>The <tt>mode &lt;mode&gt;,&lt;mode&gt;..&lt;mode&gt;</tt> line appears only if at least one of
the &lt;mode&gt; is diferent from the rest. Extended headers with
information about detected contents movement (renames and
copying detection) are designed to work with diff of two
&lt;tree-ish&gt; and are not used by combined diff format.</p>
</li>
<li>
<p>
It is followed by two-line from-file/to-file header
</p>
<div class="literalblock">
<div class="content">
<pre><tt>--- a/file
+++ b/file</tt></pre>
</div></div>
<p>Similar to two-line header for traditional <em>unified</em> diff
format, <tt>/dev/null</tt> is used to signal created or deleted
files.</p>
</li>
<li>
<p>
Chunk header format is modified to prevent people from
accidentally feeding it to <tt>patch -p1</tt>. Combined diff format
was created for review of merge commit changes, and was not
meant for apply. The change is similar to the change in the
extended <em>index</em> header:
</p>
<div class="literalblock">
<div class="content">
<pre><tt>@@@ &lt;from-file-range&gt; &lt;from-file-range&gt; &lt;to-file-range&gt; @@@</tt></pre>
</div></div>
<p>There are (number of parents + 1) <tt>@</tt> characters in the chunk
header for combined diff format.</p>
</li>
</ol>
<p>Unlike the traditional <em>unified</em> diff format, which shows two
files A and B with a single column that has <tt>-</tt> (minus &#8212;
appears in A but removed in B), <tt>+</tt> (plus &#8212; missing in A but
added to B), or <tt>" "</tt> (space &#8212; unchanged) prefix, this format
compares two or more files file1, file2,&#8230; with one file X, and
shows how X differs from each of fileN. One column for each of
fileN is prepended to the output line to note how X's line is
different from it.</p>
<p>A <tt>-</tt> character in the column N means that the line appears in
fileN but it does not appear in the result. A <tt>+</tt> character
in the column N means that the line appears in the last file,
and fileN does not have that line (in other words, the line was
added, from the point of view of that parent).</p>
<p>In the above example output, the function signature was changed
from both files (hence two <tt>-</tt> removals from both file1 and
file2, plus <tt>++</tt> to mean one line that was added does not appear
in either file1 nor file2). Also two other lines are the same
from file1 but do not appear in file2 (hence prefixed with <tt> +</tt>).</p>
<p>When shown by <tt>git diff-tree -c</tt>, it compares the parents of a
merge commit with the merge result (i.e. file1..fileN are the
parents). When shown by <tt>git diff-files -c</tt>, it compares the
two unresolved merge parents with the working tree file
(i.e. file1 is stage 2 aka "our version", file2 is stage 3 aka
"their version").</p>
</div>
<h2>Operating Modes</h2>
<div class="sectionbody">
<p>You can choose whether you want to trust the index file entirely
(using the <em>--cached</em> flag) or ask the diff logic to show any files
that don't match the stat state as being "tentatively changed". Both
of these operations are very useful indeed.</p>
</div>
<h2>Cached Mode</h2>
<div class="sectionbody">
<p>If <em>--cached</em> is specified, it allows you to ask:</p>
<div class="literalblock">
<div class="content">
<pre><tt>show me the differences between HEAD and the current index
contents (the ones I'd write with a "git-write-tree")</tt></pre>
</div></div>
<p>For example, let's say that you have worked on your working directory, updated
some files in the index and are ready to commit. You want to see exactly
<strong>what</strong> you are going to commit, without having to write a new tree
object and compare it that way, and to do that, you just do</p>
<div class="literalblock">
<div class="content">
<pre><tt>git-diff-index --cached HEAD</tt></pre>
</div></div>
<p>Example: let's say I had renamed <tt>commit.c</tt> to <tt>git-commit.c</tt>, and I had
done an "git-update-index" to make that effective in the index file.
"git-diff-files" wouldn't show anything at all, since the index file
matches my working directory. But doing a "git-diff-index" does:</p>
<div class="literalblock">
<div class="content">
<pre><tt>torvalds@ppc970:~/git&gt; git-diff-index --cached HEAD
-100644 blob 4161aecc6700a2eb579e842af0b7f22b98443f74 commit.c
+100644 blob 4161aecc6700a2eb579e842af0b7f22b98443f74 git-commit.c</tt></pre>
</div></div>
<p>You can see easily that the above is a rename.</p>
<p>In fact, "git-diff-index --cached" <strong>should</strong> always be entirely equivalent to
actually doing a "git-write-tree" and comparing that. Except this one is much
nicer for the case where you just want to check where you are.</p>
<p>So doing a "git-diff-index --cached" is basically very useful when you are
asking yourself "what have I already marked for being committed, and
what's the difference to a previous tree".</p>
</div>
<h2>Non-cached Mode</h2>
<div class="sectionbody">
<p>The "non-cached" mode takes a different approach, and is potentially
the more useful of the two in that what it does can't be emulated with
a "git-write-tree" + "git-diff-tree". Thus that's the default mode.
The non-cached version asks the question:</p>
<div class="literalblock">
<div class="content">
<pre><tt>show me the differences between HEAD and the currently checked out
tree - index contents _and_ files that aren't up-to-date</tt></pre>
</div></div>
<p>which is obviously a very useful question too, since that tells you what
you <strong>could</strong> commit. Again, the output matches the "git-diff-tree -r"
output to a tee, but with a twist.</p>
<p>The twist is that if some file doesn't match the index, we don't have
a backing store thing for it, and we use the magic "all-zero" sha1 to
show that. So let's say that you have edited <tt>kernel/sched.c</tt>, but
have not actually done a "git-update-index" on it yet - there is no
"object" associated with the new state, and you get:</p>
<div class="literalblock">
<div class="content">
<pre><tt>torvalds@ppc970:~/v2.6/linux&gt; git-diff-index HEAD
*100644-&gt;100664 blob 7476bb......-&gt;000000...... kernel/sched.c</tt></pre>
</div></div>
<p>i.e., it shows that the tree has changed, and that <tt>kernel/sched.c</tt> has is
not up-to-date and may contain new stuff. The all-zero sha1 means that to
get the real diff, you need to look at the object in the working directory
directly rather than do an object-to-object diff.</p>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">As with other commands of this type, "git-diff-index" does not
actually look at the contents of the file at all. So maybe
<tt>kernel/sched.c</tt> hasn't actually changed, and it's just that you
touched it. In either case, it's a note that you need to
"git-update-index" it to make the index be in sync.</td>
</tr></table>
</div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">You can have a mixture of files show up as "has been updated"
and "is still dirty in the working directory" together. You can always
tell which file is in which state, since the "has been updated" ones
show a valid sha1, and the "not in sync with the index" ones will
always have the special all-zero sha1.</td>
</tr></table>
</div>
</div>
<h2>Author</h2>
<div class="sectionbody">
<p>Written by Linus Torvalds &lt;torvalds@osdl.org&gt;</p>
</div>
<h2>Documentation</h2>
<div class="sectionbody">
<p>Documentation by David Greaves, Junio C Hamano and the git-list &lt;git@vger.kernel.org&gt;.</p>
</div>
<h2>GIT</h2>
<div class="sectionbody">
<p>Part of the <a href="git.html">git(7)</a> suite</p>
</div>
<div id="footer">
<div id="footer-text">
Last updated 03-Nov-2006 02:39:57 UTC
</div>
</div>
</body>
</html>