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git-diff-index - Compare a tree to the working tree or index
git diff-index [-m] [--cached] [--merge-base] [<common diff options>] <tree-ish> [<path>…]
Compares the content and mode of the blobs found in a tree object with the corresponding tracked files in the working tree, or with the corresponding paths in the index. When <path> arguments are present, compares only paths matching those patterns. Otherwise all tracked files are compared.
Generate patch (see section on generating patches).
Suppress diff output. Useful for commands like git show that
show the patch by default, or to cancel the effect of --patch.
Generate diffs with <n> lines of context instead of
the usual three.
Implies --patch.
Output to a specific file instead of stdout.
Specify the character used to indicate new, old or context lines in the generated patch. Normally they are +, - and ' ' respectively.
Generate the diff in raw format. This is the default.
Synonym for -p --raw.
Enable the heuristic that shifts diff hunk boundaries to make patches easier to read. This is the default.
Disable the indent heuristic.
Spend extra time to make sure the smallest possible diff is produced.
Generate a diff using the "patience diff" algorithm.
Generate a diff using the "histogram diff" algorithm.
Generate a diff using the "anchored diff" algorithm.
This option may be specified more than once.
If a line exists in both the source and destination, exists only once, and starts with this text, this algorithm attempts to prevent it from appearing as a deletion or addition in the output. It uses the "patience diff" algorithm internally.
Choose a diff algorithm. The variants are as follows:
default, myers The basic greedy diff algorithm. Currently, this is the default.
minimal Spend extra time to make sure the smallest possible diff is produced.
patience Use "patience diff" algorithm when generating patches.
histogram This algorithm extends the patience algorithm to "support low-occurrence common elements".
For instance, if you configured the diff.algorithm variable to a
non-default value and want to use the default one, then you
have to use --diff-algorithm=default option.
Generate a diffstat. By default, as much space as necessary
will be used for the filename part, and the rest for the graph
part. Maximum width defaults to terminal width, or 80 columns
if not connected to a terminal, and can be overridden by
<width>. The width of the filename part can be limited by
giving another width <name-width> after a comma. The width
of the graph part can be limited by using
--stat-graph-width=<width> (affects all commands generating
a stat graph) or by setting diff.statGraphWidth=<width>
(does not affect git format-patch).
By giving a third parameter <count>, you can limit the
output to the first <count> lines, followed by ... if
there are more.
These parameters can also be set individually with --stat-width=<width>,
--stat-name-width=<name-width> and --stat-count=<count>.
Output a condensed summary of extended header information such
as file creations or deletions ("new" or "gone", optionally "+l"
if it’s a symlink) and mode changes ("+x" or "-x" for adding
or removing executable bit respectively) in diffstat. The
information is put between the filename part and the graph
part. Implies --stat.
Similar to --stat, but shows number of added and
deleted lines in decimal notation and pathname without
abbreviation, to make it more machine friendly. For
binary files, outputs two - instead of saying
0 0.
Output only the last line of the --stat format containing total
number of modified files, as well as number of added and deleted
lines.
Output the distribution of relative amount of changes for each
sub-directory. The behavior of --dirstat can be customized by
passing it a comma separated list of parameters.
The defaults are controlled by the diff.dirstat configuration
variable (see git-config[1]).
The following parameters are available:
changes Compute the dirstat numbers by counting the lines that have been removed from the source, or added to the destination. This ignores the amount of pure code movements within a file. In other words, rearranging lines in a file is not counted as much as other changes. This is the default behavior when no parameter is given.
lines Compute the dirstat numbers by doing the regular line-based diff
analysis, and summing the removed/added line counts. (For binary
files, count 64-byte chunks instead, since binary files have no
natural concept of lines). This is a more expensive --dirstat
behavior than the changes behavior, but it does count rearranged
lines within a file as much as other changes. The resulting output
is consistent with what you get from the other --*stat options.
files Compute the dirstat numbers by counting the number of files changed.
Each changed file counts equally in the dirstat analysis. This is
the computationally cheapest --dirstat behavior, since it does
not have to look at the file contents at all.
cumulative Count changes in a child directory for the parent directory as well.
Note that when using cumulative, the sum of the percentages
reported may exceed 100%. The default (non-cumulative) behavior can
be specified with the noncumulative parameter.
An integer parameter specifies a cut-off percent (3% by default). Directories contributing less than this percentage of the changes are not shown in the output.
Example: The following will count changed files, while ignoring
directories with less than 10% of the total amount of changed files,
and accumulating child directory counts in the parent directories:
--dirstat=files,10,cumulative.
Synonym for --dirstat=cumulative
Synonym for --dirstat=files,param1,param2…
Output a condensed summary of extended header information such as creations, renames and mode changes.
Synonym for -p --stat.
When --raw, --numstat, --name-only or --name-status has been
given, do not munge pathnames and use NULs as output field terminators.
Without this option, pathnames with "unusual" characters are quoted as
explained for the configuration variable core.quotePath (see
git-config[1]).
Show only names of changed files.
Show only names and status of changed files. See the description
of the --diff-filter option on what the status letters mean.
Specify how differences in submodules are shown. When specifying
--submodule=short the short format is used. This format just
shows the names of the commits at the beginning and end of the range.
When --submodule or --submodule=log is specified, the log
format is used. This format lists the commits in the range like
git-submodule[1] summary does. When --submodule=diff
is specified, the diff format is used. This format shows an
inline diff of the changes in the submodule contents between the
commit range. Defaults to diff.submodule or the short format
if the config option is unset.
Show colored diff.
--color (i.e. without =<when>) is the same as --color=always.
<when> can be one of always, never, or auto.
Turn off colored diff.
It is the same as --color=never.
Moved lines of code are colored differently. The <mode> defaults to no if the option is not given and to zebra if the option with no mode is given. The mode must be one of:
Moved lines are not highlighted.
Is a synonym for zebra. This may change to a more sensible mode
in the future.
Any line that is added in one location and was removed in another location will be colored with color.diff.newMoved. Similarly color.diff.oldMoved will be used for removed lines that are added somewhere else in the diff. This mode picks up any moved line, but it is not very useful in a review to determine if a block of code was moved without permutation.
Blocks of moved text of at least 20 alphanumeric characters are detected greedily. The detected blocks are painted using either the color.diff.{old,new}Moved color. Adjacent blocks cannot be told apart.
Blocks of moved text are detected as in blocks mode. The blocks are painted using either the color.diff.{old,new}Moved color or color.diff.{old,new}MovedAlternative. The change between the two colors indicates that a new block was detected.
Similar to zebra, but additional dimming of uninteresting parts
of moved code is performed. The bordering lines of two adjacent
blocks are considered interesting, the rest is uninteresting.
dimmed_zebra is a deprecated synonym.
Turn off move detection. This can be used to override configuration
settings. It is the same as --color-moved=no.
This configures how whitespace is ignored when performing the
move detection for --color-moved.
These modes can be given as a comma separated list:
Do not ignore whitespace when performing move detection.
Ignore changes in whitespace at EOL.
Ignore changes in amount of whitespace. This ignores whitespace at line end, and considers all other sequences of one or more whitespace characters to be equivalent.
Ignore whitespace when comparing lines. This ignores differences even if one line has whitespace where the other line has none.
Initially ignore any whitespace in the move detection, then group the moved code blocks only into a block if the change in whitespace is the same per line. This is incompatible with the other modes.
Do not ignore whitespace when performing move detection. This can be
used to override configuration settings. It is the same as
--color-moved-ws=no.
Show a word diff, using the <mode> to delimit changed words.
By default, words are delimited by whitespace; see
--word-diff-regex below. The <mode> defaults to plain, and
must be one of:
Highlight changed words using only colors. Implies --color.
Show words as [-removed-] and {+added+}. Makes no
attempts to escape the delimiters if they appear in the input,
so the output may be ambiguous.
Use a special line-based format intended for script
consumption. Added/removed/unchanged runs are printed in the
usual unified diff format, starting with a +/-/` `
character at the beginning of the line and extending to the
end of the line. Newlines in the input are represented by a
tilde ~ on a line of its own.
Disable word diff again.
Note that despite the name of the first mode, color is used to highlight the changed parts in all modes if enabled.
Use <regex> to decide what a word is, instead of considering
runs of non-whitespace to be a word. Also implies
--word-diff unless it was already enabled.
Every non-overlapping match of the
<regex> is considered a word. Anything between these matches is
considered whitespace and ignored(!) for the purposes of finding
differences. You may want to append |[^[:space:]] to your regular
expression to make sure that it matches all non-whitespace characters.
A match that contains a newline is silently truncated(!) at the
newline.
For example, --word-diff-regex=. will treat each character as a word
and, correspondingly, show differences character by character.
The regex can also be set via a diff driver or configuration option, see gitattributes[5] or git-config[1]. Giving it explicitly overrides any diff driver or configuration setting. Diff drivers override configuration settings.
Equivalent to --word-diff=color plus (if a regex was
specified) --word-diff-regex=<regex>.
Turn off rename detection, even when the configuration file gives the default to do so.
Whether to use empty blobs as rename source.
Warn if changes introduce conflict markers or whitespace errors.
What are considered whitespace errors is controlled by core.whitespace
configuration. By default, trailing whitespaces (including
lines that consist solely of whitespaces) and a space character
that is immediately followed by a tab character inside the
initial indent of the line are considered whitespace errors.
Exits with non-zero status if problems are found. Not compatible
with --exit-code.
Highlight whitespace errors in the context, old or new
lines of the diff. Multiple values are separated by comma,
none resets previous values, default reset the list to
new and all is a shorthand for old,new,context. When
this option is not given, and the configuration variable
diff.wsErrorHighlight is not set, only whitespace errors in
new lines are highlighted. The whitespace errors are colored
with color.diff.whitespace.
Instead of the first handful of characters, show the full pre- and post-image blob object names on the "index" line when generating patch format output.
In addition to --full-index, output a binary diff that
can be applied with git-apply.
Implies --patch.
Instead of showing the full 40-byte hexadecimal object
name in diff-raw format output and diff-tree header
lines, show the shortest prefix that is at least <n>
hexdigits long that uniquely refers the object.
In diff-patch output format, --full-index takes higher
precedence, i.e. if --full-index is specified, full blob
names will be shown regardless of --abbrev.
Non default number of digits can be specified with --abbrev=<n>.
Break complete rewrite changes into pairs of delete and create. This serves two purposes:
It affects the way a change that amounts to a total rewrite of a file
not as a series of deletion and insertion mixed together with a very
few lines that happen to match textually as the context, but as a
single deletion of everything old followed by a single insertion of
everything new, and the number m controls this aspect of the -B
option (defaults to 60%). -B/70% specifies that less than 30% of the
original should remain in the result for Git to consider it a total
rewrite (i.e. otherwise the resulting patch will be a series of
deletion and insertion mixed together with context lines).
When used with -M, a totally-rewritten file is also considered as the
source of a rename (usually -M only considers a file that disappeared
as the source of a rename), and the number n controls this aspect of
the -B option (defaults to 50%). -B20% specifies that a change with
addition and deletion compared to 20% or more of the file’s size are
eligible for being picked up as a possible source of a rename to
another file.
Detect renames.
If n is specified, it is a threshold on the similarity
index (i.e. amount of addition/deletions compared to the
file’s size). For example, -M90% means Git should consider a
delete/add pair to be a rename if more than 90% of the file
hasn’t changed. Without a % sign, the number is to be read as
a fraction, with a decimal point before it. I.e., -M5 becomes
0.5, and is thus the same as -M50%. Similarly, -M05 is
the same as -M5%. To limit detection to exact renames, use
-M100%. The default similarity index is 50%.
Detect copies as well as renames. See also --find-copies-harder.
If n is specified, it has the same meaning as for -M<n>.
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. Giving more than one
-C option has the same effect.
Omit the preimage for deletes, i.e. print only the header but not
the diff between the preimage and /dev/null. The resulting patch
is not meant to be applied with patch or git apply; this is
solely for people who want to just concentrate on reviewing the
text after the change. In addition, the output obviously lacks
enough information to apply such a patch in reverse, even manually,
hence the name of the option.
When used together with -B, omit also the preimage in the deletion part
of a delete/create pair.
The -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.
Select only files that are Added (A), Copied (C),
Deleted (D), Modified (M), Renamed (R), have their
type (i.e. regular file, symlink, submodule, …) changed (T),
are Unmerged (U), are
Unknown (X), or have had their pairing Broken (B).
Any combination of the filter characters (including none) can be used.
When * (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.
Also, these upper-case letters can be downcased to exclude. E.g.
--diff-filter=ad excludes added and deleted paths.
Note that not all diffs can feature all types. For instance, diffs from the index to the working tree can never have Added entries (because the set of paths included in the diff is limited by what is in the index). Similarly, copied and renamed entries cannot appear if detection for those types is disabled.
Look for differences that change the number of occurrences of the specified string (i.e. addition/deletion) in a file. Intended for the scripter’s use.
It is useful when you’re looking for an exact block of code (like a
struct), and want to know the history of that block since it first
came into being: use the feature iteratively to feed the interesting
block in the preimage back into -S, and keep going until you get the
very first version of the block.
Binary files are searched as well.
Look for differences whose patch text contains added/removed lines that match <regex>.
To illustrate the difference between -S<regex> --pickaxe-regex and
-G<regex>, consider a commit with the following diff in the same
file:
+ return frotz(nitfol, two->ptr, 1, 0); ... - hit = frotz(nitfol, mf2.ptr, 1, 0);
While git log -G"frotz\(nitfol" will show this commit, git log -S"frotz\(nitfol" --pickaxe-regex will not (because the number of occurrences of that string did not change).
Unless --text is supplied patches of binary files without a textconv
filter will be ignored.
See the pickaxe entry in gitdiffcore[7] for more information.
Look for differences that change the number of occurrences of
the specified object. Similar to -S, just the argument is different
in that it doesn’t search for a specific string but for a specific
object id.
The object can be a blob or a submodule commit. It implies the -t option in
git-log to also find trees.
When -S or -G finds a change, show all the changes in that
changeset, not just the files that contain the change
in <string>.
Treat the <string> given to -S as an extended POSIX regular
expression to match.
Control the order in which files appear in the output.
This overrides the diff.orderFile configuration variable
(see git-config[1]). To cancel diff.orderFile,
use -O/dev/null.
The output order is determined by the order of glob patterns in <orderfile>. All files with pathnames that match the first pattern are output first, all files with pathnames that match the second pattern (but not the first) are output next, and so on. All files with pathnames that do not match any pattern are output last, as if there was an implicit match-all pattern at the end of the file. If multiple pathnames have the same rank (they match the same pattern but no earlier patterns), their output order relative to each other is the normal order.
<orderfile> is parsed as follows:
Blank lines are ignored, so they can be used as separators for readability.
Lines starting with a hash ("#") are ignored, so they can be used
for comments. Add a backslash ("\") to the beginning of the
pattern if it starts with a hash.
Each other line contains a single pattern.
Patterns have the same syntax and semantics as patterns used for
fnmatch(3) without the FNM_PATHNAME flag, except a pathname also
matches a pattern if removing any number of the final pathname
components matches the pattern. For example, the pattern "foo*bar"
matches "fooasdfbar" and "foo/bar/baz/asdf" but not "foobarx".
Discard the files before the named <file> from the output
(i.e. skip to), or move them to the end of the output
(i.e. rotate to). These were invented primarily for use
of the git difftool command, and may not be very useful
otherwise.
Swap two inputs; that is, show differences from index or on-disk file to tree contents.
When run from a subdirectory of the project, it can be
told to exclude changes outside the directory and show
pathnames relative to it with this option. When you are
not in a subdirectory (e.g. in a bare repository), you
can name which subdirectory to make the output relative
to by giving a <path> as an argument.
--no-relative can be used to countermand both diff.relative config
option and previous --relative.
Treat all files as text.
Ignore carriage-return at the end of line when doing a comparison.
Ignore changes in whitespace at EOL.
Ignore changes in amount of whitespace. This ignores whitespace at line end, and considers all other sequences of one or more whitespace characters to be equivalent.
Ignore whitespace when comparing lines. This ignores differences even if one line has whitespace where the other line has none.
Ignore changes whose lines are all blank.
Ignore changes whose all lines match <regex>. This option may be specified more than once.
Show the context between diff hunks, up to the specified number
of lines, thereby fusing hunks that are close to each other.
Defaults to diff.interHunkContext or 0 if the config option
is unset.
Show whole function as context lines for each change.
The function names are determined in the same way as
git diff works out patch hunk headers (see Defining a
custom hunk-header in gitattributes[5]).
Make the program exit with codes similar to diff(1). That is, it exits with 1 if there were differences and 0 means no differences.
Disable all output of the program. Implies --exit-code.
Allow an external diff helper to be executed. If you set an external diff driver with gitattributes[5], you need to use this option with git-log[1] and friends.
Disallow external diff drivers.
Allow (or disallow) external text conversion filters to be run when comparing binary files. See gitattributes[5] for details. Because textconv filters are typically a one-way conversion, the resulting diff is suitable for human consumption, but cannot be applied. For this reason, textconv filters are enabled by default only for git-diff[1] and git-log[1], but not for git-format-patch[1] or diff plumbing commands.
Ignore changes to submodules in the diff generation. <when> can be either "none", "untracked", "dirty" or "all", which is the default. Using "none" will consider the submodule modified when it either contains untracked or modified files or its HEAD differs from the commit recorded in the superproject and can be used to override any settings of the ignore option in git-config[1] or gitmodules[5]. When "untracked" is used submodules are not considered dirty when they only contain untracked content (but they are still scanned for modified content). Using "dirty" ignores all changes to the work tree of submodules, only changes to the commits stored in the superproject are shown (this was the behavior until 1.7.0). Using "all" hides all changes to submodules.
Show the given source prefix instead of "a/".
Show the given destination prefix instead of "b/".
Do not show any source or destination prefix.
Prepend an additional prefix to every line of output.
By default entries added by "git add -N" appear as an existing
empty file in "git diff" and a new file in "git diff --cached".
This option makes the entry appear as a new file in "git diff"
and non-existent in "git diff --cached". This option could be
reverted with --ita-visible-in-index. Both options are
experimental and could be removed in future.
For more detailed explanation on these common options, see also gitdiffcore[7].
The id of a tree object to diff against.
Do not consider the on-disk file at all.
Instead of comparing <tree-ish> directly, use the merge base between <tree-ish> and HEAD instead. <tree-ish> must be a commit.
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.
The raw output format from "git-diff-index", "git-diff-tree", "git-diff-files" and "git diff --raw" are very similar.
These commands all compare two sets of things; what is compared differs:
compares the <tree-ish> and the files on the filesystem.
compares the <tree-ish> and the index.
compares the trees named by the two arguments.
compares the index and the files on the filesystem.
The "git-diff-tree" command begins its output by printing the hash of what is being compared. After that, all the commands print one output line per changed file.
An output line is formatted this way:
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
That is, from the left to the right:
a colon.
mode for "src"; 000000 if creation or unmerged.
a space.
mode for "dst"; 000000 if deletion or unmerged.
a space.
sha1 for "src"; 0{40} if creation or unmerged.
a space.
sha1 for "dst"; 0{40} if creation, unmerged or "look at work tree".
a space.
status, followed by optional "score" number.
a tab or a NUL when -z option is used.
path for "src"
a tab or a NUL when -z option is used; only exists for C or R.
path for "dst"; only exists for C or R.
an LF or a NUL when -z option is used, to terminate the record.
Possible status letters are:
A: addition of a file
C: copy of a file into a new one
D: deletion of a file
M: modification of the contents or mode of a file
R: renaming of a file
T: change in the type of the file
U: file is unmerged (you must complete the merge before it can be committed)
X: "unknown" change type (most probably a bug, please report it)
Status letters C and R are always followed by a score (denoting the percentage of similarity between the source and target of the move or copy). Status letter M may be followed by a score (denoting the percentage of dissimilarity) for file rewrites.
<sha1> is shown as all 0’s if a file is new on the filesystem and it is out of sync with the index.
Example:
:100644 100644 5be4a4a 0000000 M file.c
Without the -z option, pathnames with "unusual" characters are
quoted as explained for the configuration variable core.quotePath
(see git-config[1]). Using -z the filename is output
verbatim and the line is terminated by a NUL byte.
"git-diff-tree", "git-diff-files" and "git-diff --raw"
can take -c or --cc option
to generate diff output also for merge commits. The output differs
from the format described above in the following way:
there is a colon for each parent
there are more "src" modes and "src" sha1
status is concatenated status characters for each parent
no optional "score" number
tab-separated pathname(s) of the file
For -c and --cc, only the destination or final path is shown even
if the file was renamed on any side of history. With
--combined-all-paths, the name of the path in each parent is shown
followed by the name of the path in the merge commit.
Examples for -c and --cc without --combined-all-paths:
::100644 100644 100644 fabadb8 cc95eb0 4866510 MM desc.c ::100755 100755 100755 52b7a2d 6d1ac04 d2ac7d7 RM bar.sh ::100644 100644 100644 e07d6c5 9042e82 ee91881 RR phooey.c
Examples when --combined-all-paths added to either -c or --cc:
::100644 100644 100644 fabadb8 cc95eb0 4866510 MM desc.c desc.c desc.c ::100755 100755 100755 52b7a2d 6d1ac04 d2ac7d7 RM foo.sh bar.sh bar.sh ::100644 100644 100644 e07d6c5 9042e82 ee91881 RR fooey.c fuey.c phooey.c
Note that combined diff lists only files which were modified from all parents.
Running
git-diff[1],
git-log[1],
git-show[1],
git-diff-index[1],
git-diff-tree[1], or
git-diff-files[1]
with the -p option produces patch text.
You can customize the creation of patch text via the
GIT_EXTERNAL_DIFF and the GIT_DIFF_OPTS environment variables
(see git[1]).
What the -p option produces is slightly different from the traditional diff format:
It is preceded with a "git diff" header that looks like this:
diff --git a/file1 b/file2
The a/ and b/ filenames are the same unless rename/copy is
involved. Especially, even for a creation or a deletion,
/dev/null is not used in place of the a/ or b/ filenames.
When rename/copy is involved, file1 and file2 show the
name of the source file of the rename/copy and the name of
the file that rename/copy produces, respectively.
It is followed by one or more extended header lines:
old mode <mode> new mode <mode> deleted file mode <mode> new file mode <mode> copy from <path> copy to <path> rename from <path> rename to <path> similarity index <number> dissimilarity index <number> index <hash>..<hash> <mode>
File modes are printed as 6-digit octal numbers including the file type and file permission bits.
Path names in extended headers do not include the a/ and b/ prefixes.
The similarity index is the percentage of unchanged lines, and the dissimilarity index is the percentage of changed lines. It is a rounded down integer, followed by a percent sign. The similarity index value of 100% is thus reserved for two equal files, while 100% dissimilarity means that no line from the old file made it into the new one.
The index line includes the blob object names before and after the change. The <mode> is included if the file mode does not change; otherwise, separate lines indicate the old and the new mode.
Pathnames with "unusual" characters are quoted as explained for
the configuration variable core.quotePath (see
git-config[1]).
All the file1 files in the output refer to files before the
commit, and all the file2 files refer to files after the commit.
It is incorrect to apply each change to each file sequentially. For
example, this patch will swap a and b:
diff --git a/a b/b rename from a rename to b diff --git a/b b/a rename from b rename to a
Any diff-generating command can take the -c or --cc option to
produce a combined diff when showing a merge. This is the default
format when showing merges with git-diff[1] or
git-show[1]. Note also that you can give suitable
--diff-merges option to any of these commands to force generation of
diffs in specific format.
A "combined diff" format looks like this:
diff --combined describe.c
index fabadb8,cc95eb0..4866510
--- a/describe.c
+++ b/describe.c
@@@ -98,20 -98,12 +98,20 @@@
return (a_date > 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) < 0)
+ usage(describe_usage);
+ cmit = lookup_commit_reference(sha1);
+ if (!cmit)
+ usage(describe_usage);
+
if (!initialized) {
initialized = 1;
for_each_ref(get_name);
It is preceded with a "git diff" header, that looks like
this (when the -c option is used):
diff --combined file
or like this (when the --cc option is used):
diff --cc file
It is followed by one or more extended header lines (this example shows a merge with two parents):
index <hash>,<hash>..<hash> mode <mode>,<mode>..<mode> new file mode <mode> deleted file mode <mode>,<mode>
The mode <mode>,<mode>..<mode> line appears only if at least one of
the <mode> is different from the rest. Extended headers with
information about detected contents movement (renames and
copying detection) are designed to work with diff of two
<tree-ish> and are not used by combined diff format.
It is followed by two-line from-file/to-file header
--- a/file +++ b/file
Similar to two-line header for traditional unified diff
format, /dev/null is used to signal created or deleted
files.
However, if the --combined-all-paths option is provided, instead of a two-line from-file/to-file you get a N+1 line from-file/to-file header, where N is the number of parents in the merge commit
--- a/file --- a/file --- a/file +++ b/file
This extended format can be useful if rename or copy detection is active, to allow you to see the original name of the file in different parents.
Chunk header format is modified to prevent people from
accidentally feeding it to patch -p1. Combined diff format
was created for review of merge commit changes, and was not
meant to be applied. The change is similar to the change in the
extended index header:
@@@ <from-file-range> <from-file-range> <to-file-range> @@@
There are (number of parents + 1) @ characters in the chunk
header for combined diff format.
Unlike the traditional unified diff format, which shows two
files A and B with a single column that has - (minus — appears in A but removed in B), + (plus — missing in A but
added to B), or " " (space — unchanged) prefix, this format
compares two or more files file1, file2,… 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.
A - character in the column N means that the line appears in
fileN but it does not appear in the result. A + character
in the column N means that the line appears in the result,
and fileN does not have that line (in other words, the line was
added, from the point of view of that parent).
In the above example output, the function signature was changed
from both files (hence two - removals from both file1 and
file2, plus ++ to mean one line that was added does not appear
in either file1 or file2). Also eight other lines are the same
from file1 but do not appear in file2 (hence prefixed with +).
When shown by git diff-tree -c, it compares the parents of a
merge commit with the merge result (i.e. file1..fileN are the
parents). When shown by git diff-files -c, 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").
The --summary option describes newly added, deleted, renamed and
copied files. The --stat option adds diffstat(1) graph to the
output. These options can be combined with other options, such as
-p, and are meant for human consumption.
When showing a change that involves a rename or a copy, --stat output
formats the pathnames compactly by combining common prefix and suffix of
the pathnames. For example, a change that moves arch/i386/Makefile to
arch/x86/Makefile while modifying 4 lines will be shown like this:
arch/{i386 => x86}/Makefile | 4 +--
The --numstat option gives the diffstat(1) information but is designed
for easier machine consumption. An entry in --numstat output looks
like this:
1 2 README
3 1 arch/{i386 => x86}/Makefile
That is, from left to right:
the number of added lines;
a tab;
the number of deleted lines;
a tab;
pathname (possibly with rename/copy information);
a newline.
When -z output option is in effect, the output is formatted this way:
1 2 README NUL 3 1 NUL arch/i386/Makefile NUL arch/x86/Makefile NUL
That is:
the number of added lines;
a tab;
the number of deleted lines;
a tab;
a NUL (only exists if renamed/copied);
pathname in preimage;
a NUL (only exists if renamed/copied);
pathname in postimage (only exists if renamed/copied);
a NUL.
The extra NUL before the preimage path in renamed case is to allow
scripts that read the output to tell if the current record being read is
a single-path record or a rename/copy record without reading ahead.
After reading added and deleted lines, reading up to NUL would yield
the pathname, but if that is NUL, the record will show two paths.
You can choose whether you want to trust the index file entirely
(using the --cached 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.
If --cached is specified, it allows you to ask:
show me the differences between HEAD and the current index contents (the ones I'd write using 'git write-tree')
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 what 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
git diff-index --cached HEAD
Example: let’s say I had renamed commit.c to git-commit.c, and I had
done an 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:
torvalds@ppc970:~/git> git diff-index --cached HEAD -100644 blob 4161aecc6700a2eb579e842af0b7f22b98443f74 commit.c +100644 blob 4161aecc6700a2eb579e842af0b7f22b98443f74 git-commit.c
You can see easily that the above is a rename.
In fact, git diff-index --cached should 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.
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".
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:
show me the differences between HEAD and the currently checked out tree - index contents _and_ files that aren't up to date
which is obviously a very useful question too, since that tells you what you could commit. Again, the output matches the git diff-tree -r output to a tee, but with a twist.
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 kernel/sched.c, but
have not actually done a git update-index on it yet - there is no
"object" associated with the new state, and you get:
torvalds@ppc970:~/v2.6/linux> git diff-index --abbrev HEAD :100644 100664 7476bb... 000000... kernel/sched.c
i.e., it shows that the tree has changed, and that kernel/sched.c 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.
|
Note
|
As with other commands of this type, git diff-index does not
actually look at the contents of the file at all. So maybe
kernel/sched.c 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.
|
|
Note
|
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. |
Part of the git[1] suite