GIT-DIFF-TREE(1)

NAME
git-diff-tree - Compares the content and mode of blobs found via two tree objects

SYNOPSIS

git diff-tree [--stdin] [-m] [-s] [-v] [--no-commit-id] [--pretty]
              [-t] [-r] [-c | --cc] [--root] [<common diff options>]
              <tree-ish> [<tree-ish>] [<path>...]

DESCRIPTION

Compares the content and mode of the blobs found via two tree objects.

If there is only one <tree-ish> given, the commit is compared with its parents (see --stdin below).

Note that git diff-tree can use the tree encapsulated in a commit object.

OPTIONS

-p, -u, --patch
    Generate patch (see section on generating patches).

-U<n>, --unified=<n>
    Generate diffs with <n> lines of context instead of the usual three. Implies -p.

--raw
    Generate the raw format. This is the default.

--patch-with-raw
    Synonym for -p --raw.

--minimal
    Spend extra time to make sure the smallest possible diff is produced.

--patience
    Generate a diff using the "patience diff" algorithm.

--histogram
    Generate a diff using the "histogram diff" algorithm.

--stat[=<width>[,<name-width>[,<count>]]]
    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>.

--numstat
    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.

--shortstat
    Output only the last line of the --stat format containing total number of modified files, as well as number of added and deleted lines.

--dirstat[=<param1,param2,...>]
    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.

    <limit>
        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.

--summary
    Output a condensed summary of extended header information such as creations, renames and mode changes.

--patch-with-stat
    Synonym for -p --stat.

-z
    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, each pathname output will have TAB, LF, double quotes, and backslash characters replaced with \t, \n, \", and \\, respectively, and the pathname will be enclosed in double quotes if any of those replacements occurred.

--name-only
    Show only names of changed files.

--name-status
    Show only names and status of changed files. See the description of the --diff-filter option on what the status letters mean.

--submodule[=<format>]
    Specify how differences in submodules are shown. When --submodule or --submodule=log is given, the log format is used. This format lists the commits in the range like git-submodule(1) summary does. Omitting the --submodule option or specifying --submodule=short, uses the short format. This format just shows the names of the commits at the beginning and end of the range. Can be tweaked via the diff.submodule configuration variable.

--color[=<when>]
    Show colored diff. The value must be always (the default for <when>), never, or auto. The default value is never.

--no-color
    Turn off colored diff. It is the same as --color=never.

--word-diff[=<mode>]
    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:

    color
        Highlight changed words using only colors. Implies --color.

    plain
        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.

    porcelain
        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.

    none
        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.

--word-diff-regex=<regex>
    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.

    The regex can also be set via a diff driver or configuration option, see gitattributes(1) or git-config(1). Giving it explicitly overrides any diff driver or configuration setting. Diff drivers override configuration settings.

--color-words[=<regex>]
    Equivalent to --word-diff=color plus (if a regex was specified) --word-diff-regex=<regex>.

--no-renames
    Turn off rename detection, even when the configuration file gives the default to do so.

--check
    Warn if changes introduce whitespace errors. What are considered whitespace errors is controlled by core.whitespace configuration. By default, trailing whitespaces (including lines that solely consist 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.

--full-index
    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.

--binary
    In addition to --full-index, output a binary diff that can be applied with git-apply.

--abbrev[=<n>]
    Instead of showing the full 40-byte hexadecimal object name in diff-raw format output and diff-tree header lines, show only a partial prefix. This is independent of the --full-index option above, which controls the diff-patch output format. Non default number of digits can be specified with --abbrev=<n>.

-B[<n>][/<m>], --break-rewrites[=[<n>][/<m>]]
    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.

-M[<n>], --find-renames[=<n>]
    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%.

-C[<n>], --find-copies[=<n>]
    Detect copies as well as renames. See also --find-copies-harder. If n is specified, it has the same meaning as for -M<n>.

--find-copies-harder
    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.

-D, --irreversible-delete
    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 nor git apply; this is solely for people who want to just concentrate on reviewing the text after the change. In addition, the output obviously lack 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.

-l<num>
    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.

--diff-filter=[(A|C|D|M|R|T|U|X|B)...[*]]
    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.

-S<string>
    Look for differences that introduce or remove an instance of <string>. Note that this is different than the string simply appearing in diff output; see the pickaxe entry in gitdiffcore(7) for more details.

-G<regex>
    Look for differences whose added or removed line matches the given <regex>.

--pickaxe-all
    When -S or -G finds a change, show all the changes in that changeset, not just the files that contain the change in <string>.

--pickaxe-regex
    Make the <string> not a plain string but an extended POSIX regex to match.

-O<orderfile>
    Output the patch in the order specified in the <orderfile>, which has one shell glob pattern per line.

-R
    Swap two inputs; that is, show differences from index or on-disk file to tree contents.

--relative[=<path>]
    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.

-a, --text
    Treat all files as text.

--ignore-space-at-eol
    Ignore changes in whitespace at EOL.

-b, --ignore-space-change
    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.

-w, --ignore-all-space
    Ignore whitespace when comparing lines. This ignores differences even if one line has whitespace where the other line has none.

--inter-hunk-context=<lines>
    Show the context between diff hunks, up to the specified number of lines, thereby fusing hunks that are close to each other.

-W, --function-context
    Show whole surrounding functions of changes.

--exit-code
    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.

--quiet
    Disable all output of the program. Implies --exit-code.

--ext-diff
    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.

--no-ext-diff
    Disallow external diff drivers.

--textconv, --no-textconv
    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-submodules[=<when>]
    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.

--src-prefix=<prefix>
    Show the given source prefix instead of "a/".

--dst-prefix=<prefix>
    Show the given destination prefix instead of "b/".

--no-prefix
    Do not show any source or destination prefix.

For more detailed explanation on these common options, see also gitdiffcore(7).

<tree-ish>
    The id of a tree object.

<path>...
    If provided, the results are limited to a subset of files matching one of these prefix strings. i.e., file matches /^<pattern1>|<pattern2>|.../ Note that this parameter does not provide any wildcard or regexp features.

-r
    recurse into sub-trees

-t
    show tree entry itself as well as subtrees. Implies -r.

--root
    When --root is specified the initial commit will be shown as a big creation event. This is equivalent to a diff against the NULL tree.

--stdin
    When --stdin is specified, the command does not take <tree-ish> arguments from the command line. Instead, it reads lines containing either two <tree>, one <commit>, or a list of <commit> from its standard input. (Use a single space as separator.)

    When two trees are given, it compares the first tree with the second. When a single commit is given, it compares the commit with its parents. The remaining commits, when given, are used as if they are parents of the first commit.

    When comparing two trees, the ID of both trees (separated by a space and terminated by a newline) is printed before the difference. When comparing commits, the ID of the first (or only) commit, followed by a newline, is printed.

    The following flags further affect the behavior when comparing commits (but not trees).

-m
    By default, git diff-tree --stdin does not show differences for merge commits. With this flag, it shows differences to that commit from all of its parents. See also -c.

-s
    By default, git diff-tree --stdin shows differences, either in machine-readable form (without -p) or in patch form (with -p). This output can be suppressed. It is only useful with -v flag.

-v
    This flag causes git diff-tree --stdin to also show the commit message before the differences.

--pretty[=<format>], --format=<format>
    Pretty-print the contents of the commit logs in a given format, where <format> can be one of oneline, short, medium, full, fuller, email, raw and format:<string>. See the "PRETTY FORMATS" section for some additional details for each format. When omitted, the format defaults to medium.

    Note: you can specify the default pretty format in the repository configuration (see git-config(1)).

--abbrev-commit
    Instead of showing the full 40-byte hexadecimal commit object name, show only a partial prefix. Non default number of digits can be specified with "--abbrev=<n>" (which also modifies diff output, if it is displayed).

    This should make "--pretty=oneline" a whole lot more readable for people using 80-column terminals.

--no-abbrev-commit
    Show the full 40-byte hexadecimal commit object name. This negates --abbrev-commit and those options which imply it such as "--oneline". It also overrides the log.abbrevCommit variable.

--oneline
    This is a shorthand for "--pretty=oneline --abbrev-commit" used together.

--encoding[=<encoding>]
    The commit objects record the encoding used for the log message in their encoding header; this option can be used to tell the command to re-code the commit log message in the encoding preferred by the user. For non plumbing commands this defaults to UTF-8.

--notes[=<ref>]
    Show the notes (see git-notes(1)) that annotate the commit, when showing the commit log message. This is the default for git log, git show and git whatchanged commands when there is no --pretty, --format nor --oneline option given on the command line.

    By default, the notes shown are from the notes refs listed in the core.notesRef and notes.displayRef variables (or corresponding environment overrides). See git-config(1) for more details.

    With an optional <ref> argument, show this notes ref instead of the default notes ref(s). The ref is taken to be in refs/notes/ if it is not qualified.

    Multiple --notes options can be combined to control which notes are being displayed. Examples: "--notes=foo" will show only notes from "refs/notes/foo"; "--notes=foo --notes" will show both notes from "refs/notes/foo" and from the default notes ref(s).

--no-notes
    Do not show notes. This negates the above --notes option, by resetting the list of notes refs from which notes are shown. Options are parsed in the order given on the command line, so e.g. "--notes --notes=foo --no-notes --notes=bar" will only show notes from "refs/notes/bar".

--show-notes[=<ref>], --[no-]standard-notes
    These options are deprecated. Use the above --notes/--no-notes options instead.

--show-signature
    Check the validity of a signed commit object by passing the signature to gpg --verify and show the output.

--no-commit-id
    git diff-tree outputs a line with the commit ID when applicable. This flag suppressed the commit ID output.

-c
    This flag changes the way a merge commit is displayed (which means it is useful only when the command is given one <tree-ish>, or --stdin). It shows the differences from each of the parents to the merge result simultaneously instead of showing pairwise diff between a parent and the result one at a time (which is what the -m option does). Furthermore, it lists only files which were modified from all parents.

--cc
    This flag changes the way a merge commit patch is displayed, in a similar way to the -c option. It implies the -c and -p options and further compresses the patch output by omitting uninteresting hunks whose the contents in the parents have only two variants and the merge result picks one of them without modification. When all hunks are uninteresting, the commit itself and the commit log message is not shown, just like in any other "empty diff" case.

--always
    Show the commit itself and the commit log message even if the diff itself is empty.

PRETTY FORMATS

If the commit is a merge, and if the pretty-format is not oneline, email or raw, an additional line is inserted before the Author: line. This line begins with "Merge: " and the sha1s of ancestral commits are printed, separated by spaces. Note that the listed commits may not necessarily be the list of the direct parent commits if you have limited your view of history: for example, if you are only interested in changes related to a certain directory or file.

There are several built-in formats, and you can define additional formats by setting a pretty.<name> config option to either another format name, or a format: string, as described below (see git-config(1)). Here are the details of the built-in formats:

    • oneline

        <sha1> <title line>

    This is designed to be as compact as possible.

    • short

        commit <sha1>
        Author: <author>

        <title line>

    • medium

        commit <sha1>
        Author: <author>
        Date:   <author date>

        <title line>

        <full commit message>

    • full

        commit <sha1>
        Author: <author>
        Commit: <committer>

        <title line>

        <full commit message>

    • fuller

        commit <sha1>
        Author:     <author>
        AuthorDate: <author date>
        Commit:     <committer>
        CommitDate: <committer date>

        <title line>

        <full commit message>

    • email

        From <sha1> <date>
        From: <author>
        Date: <author date>
        Subject: [PATCH] <title line>

        <full commit message>

    • raw

    The raw format shows the entire commit exactly as stored in the commit object. Notably, the SHA1s are displayed in full, regardless of whether --abbrev or --no-abbrev are used, and parents information show the true parent commits, without taking grafts nor history simplification into account.

    • format:<string>

    The format:<string> format allows you to specify which information you want to show. It works a little bit like printf format, with the notable exception that you get a newline with %n instead of \n.

    E.g, format:"The author of %h was %an, %ar%nThe title was >>%s<<%n" would show something like this:

        The author of fe6e0ee was Junio C Hamano, 23 hours ago
        The title was >>t4119: test autocomputing -p<n> for traditional diff input.<<

    The placeholders are:

        • %H: commit hash

        • %h: abbreviated commit hash

        • %T: tree hash

        • %t: abbreviated tree hash

        • %P: parent hashes

        • %p: abbreviated parent hashes

        • %an: author name

        • %aN: author name (respecting .mailmap, see git-shortlog(1) or git-blame(1))

        • %ae: author email

        • %aE: author email (respecting .mailmap, see git-shortlog(1) or git-blame(1))

        • %ad: author date (format respects --date= option)

        • %aD: author date, RFC2822 style

        • %ar: author date, relative

        • %at: author date, UNIX timestamp

        • %ai: author date, ISO 8601 format

        • %cn: committer name

        • %cN: committer name (respecting .mailmap, see git-shortlog(1) or git-blame(1))

        • %ce: committer email

        • %cE: committer email (respecting .mailmap, see git-shortlog(1) or git-blame(1))

        • %cd: committer date

        • %cD: committer date, RFC2822 style

        • %cr: committer date, relative

        • %ct: committer date, UNIX timestamp

        • %ci: committer date, ISO 8601 format

        • %d: ref names, like the --decorate option of git-log(1)

        • %e: encoding

        • %s: subject

        • %f: sanitized subject line, suitable for a filename

        • %b: body

        • %B: raw body (unwrapped subject and body)

        • %N: commit notes

        • %GG: raw verification message from GPG for a signed commit

        • %G?: show either "G" for Good or "B" for Bad for a signed commit

        • %GS: show the name of the signer for a signed commit

        • %gD: reflog selector, e.g., refs/stash@{1}

        • %gd: shortened reflog selector, e.g., stash@{1}

        • %gn: reflog identity name

        • %gN: reflog identity name (respecting .mailmap, see git-shortlog(1) or git-blame(1))

        • %ge: reflog identity email

        • %gE: reflog identity email (respecting .mailmap, see git-shortlog(1) or git-blame(1))

        • %gs: reflog subject

        • %Cred: switch color to red

        • %Cgreen: switch color to green

        • %Cblue: switch color to blue

        • %Creset: reset color

        • %C(...): color specification, as described in color.branch.* config option

        • %m: left, right or boundary mark

        • %n: newline

        • %%: a raw %

        • %x00: print a byte from a hex code

        • %w([<w>[,<i1>[,<i2>]]]): switch line wrapping, like the -w option of git-shortlog(1).

    Note

    Some placeholders may depend on other options given to the revision traversal engine. For example, the %g* reflog options will insert an empty string unless we are traversing reflog entries (e.g., by git log -g). The %d placeholder will use the "short" decoration format if --decorate was not already provided on the command line.

If you add a + (plus sign) after % of a placeholder, a line-feed is inserted immediately before the expansion if and only if the placeholder expands to a non-empty string.

If you add a - (minus sign) after % of a placeholder, line-feeds that immediately precede the expansion are deleted if and only if the placeholder expands to an empty string.

If you add a ` ` (space) after % of a placeholder, a space is inserted immediately before the expansion if and only if the placeholder expands to a non-empty string.

    • tformat:

    The tformat: format works exactly like format:, except that it provides "terminator" semantics instead of "separator" semantics. In other words, each commit has the message terminator character (usually a newline) appended, rather than a separator placed between entries. This means that the final entry of a single-line format will be properly terminated with a new line, just as the "oneline" format does. For example:

        $ git log -2 --pretty=format:%h 4da45bef \
          | perl -pe '$_ .= " -- NO NEWLINE\n" unless /\n/'
        4da45be
        7134973 -- NO NEWLINE
        $ git log -2 --pretty=tformat:%h 4da45bef \
          | perl -pe '$_ .= " -- NO NEWLINE\n" unless /\n/'
        4da45be
        7134973

    In addition, any unrecognized string that has a % in it is interpreted as if it has tformat: in front of it. For example, these two are equivalent:

        $ git log -2 --pretty=tformat:%h 4da45bef
        $ git log -2 --pretty=%h 4da45bef

LIMITING OUTPUT

If you’re only interested in differences in a subset of files, for example some architecture-specific files, you might do:

    git diff-tree -r <tree-ish> <tree-ish> arch/ia64 include/asm-ia64

and it will only show you what changed in those two directories.

Or if you are searching for what changed in just kernel/sched.c, just do

    git diff-tree -r <tree-ish> <tree-ish> kernel/sched.c

and it will ignore all differences to other files.

The pattern is always the prefix, and is matched exactly. There are no wildcards. Even stricter, it has to match a complete path component. I.e. "foo" does not pick up foobar.h. "foo" does match foo/bar.h so it can be used to name subdirectories.

An example of normal usage is:

    torvalds@ppc970:~/git> git diff-tree --abbrev 5319e4
    :100664 100664 ac348b... a01513...    git-fsck-objects.c

which tells you that the last commit changed just one file (it’s from this one:

    commit 3c6f7ca19ad4043e9e72fa94106f352897e651a8
    tree 5319e4d609cdd282069cc4dce33c1db559539b03
    parent b4e628ea30d5ab3606119d2ea5caeab141d38df7
    author Linus Torvalds <torvalds@ppc970.osdl.org> Sat Apr 9 12:02:30 2005
    committer Linus Torvalds <torvalds@ppc970.osdl.org> Sat Apr 9 12:02:30 2005
    Make "git-fsck-objects" print out all the root commits it finds.
    Once I do the reference tracking, I'll also make it print out all the
    HEAD commits it finds, which is even more interesting.

in case you care).

RAW OUTPUT FORMAT

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:

git-diff-index <tree-ish>
    compares the <tree-ish> and the files on the filesystem.

git-diff-index --cached <tree-ish>
    compares the <tree-ish> and the index.

git-diff-tree [-r] <tree-ish-1> <tree-ish-2> [<pattern>...]
    compares the trees named by the two arguments.

git-diff-files [<pattern>...]
    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:

    1. a colon.

    2. mode for "src"; 000000 if creation or unmerged.

    3. a space.

    4. mode for "dst"; 000000 if deletion or unmerged.

    5. a space.

    6. sha1 for "src"; 0{40} if creation or unmerged.

    7. a space.

    8. sha1 for "dst"; 0{40} if creation, unmerged or "look at work tree".

    9. a space.

    10. status, followed by optional "score" number.

    11. a tab or a NUL when -z option is used.

    12. path for "src"

    13. a tab or a NUL when -z option is used; only exists for C or R.

    14. path for "dst"; only exists for C or R.

    15. 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), and are the only ones to be so.

<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 5be4a4...... 000000...... M file.c

When -z option is not used, TAB, LF, and backslash characters in pathnames are represented as \t, \n, and \\, respectively.

DIFF FORMAT FOR MERGES

"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:

    1. there is a colon for each parent

    2. there are more "src" modes and "src" sha1

    3. status is concatenated status characters for each parent

    4. no optional "score" number

    5. single path, only for "dst"

Example:

    ::100644 100644 100644 fabadb8... cc95eb0... 4866510... MM      describe.c

Note that combined diff lists only files which were modified from all parents.

GENERATING PATCHES WITH -P

When "git-diff-index", "git-diff-tree", or "git-diff-files" are run with a -p option, "git diff" without the --raw option, or "git log" with the "-p" option, they do not produce the output described above; instead they produce a patch file. You can customize the creation of such patches via the GIT_EXTERNAL_DIFF and the GIT_DIFF_OPTS environment variables.

What the -p option produces is slightly different from the traditional diff format:

    1. 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.

    2. 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 SHA-1 checksum 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.

    3. TAB, LF, double quote and backslash characters in pathnames are represented as \t, \n, \" and \\, respectively. If there is need for such substitution then the whole pathname is put in double quotes.

    4. 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

COMBINED DIFF FORMAT

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 the `-m’ option to any of these commands to force generation of diffs with individual parents of a merge.

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);

    1. It is preceded with a "git diff" header, that looks like this (when -c option is used):

        diff --combined file

    or like this (when --cc option is used):

        diff --cc file

    2. 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.

    3. 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.

    4. 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 for apply. 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 nor 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").

OTHER DIFF FORMATS

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:

    1. the number of added lines;

    2. a tab;

    3. the number of deleted lines;

    4. a tab;

    5. pathname (possibly with rename/copy information);

    6. 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:

    1. the number of added lines;

    2. a tab;

    3. the number of deleted lines;

    4. a tab;

    5. a NUL (only exists if renamed/copied);

    6. pathname in preimage;

    7. a NUL (only exists if renamed/copied);

    8. pathname in postimage (only exists if renamed/copied);

    9. 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.

GIT

Part of the git(1) suite