GIT-DIFF-PAIRS(1)

📦
version 2.56.0 · 15 versions
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💅 GIT-DIFF-PAIRS(1) — Git Manual ✨

ok so bestie, this is git-diff-pairs, and before you panic — it's actually so good. It's from the Git Manual, it lives in the git-diff-pairs corner of the world, and it's about comparing the content and mode of blob pairs you hand it. yes, "blob pairs." stay with me 🫶

🌸 NAME 🌸

git-diff-pairs — compare the content and mode of provided blob pairs. that's the whole vibe check. 💖

✨ SYNOPSIS ✨

git diff-pairs -z [<diff-options>]

that -z is not optional, bestie, it's literally in the synopsis. note it. 🎀

💜 DESCRIPTION 💜

so here's the tea: this command shows you the changes for file pairs you provide on stdin. and the input must be in the NUL-terminated raw output format — the kind of thing commands like git diff-tree -z -r --raw generate. By default, the diffs it outputs are computed and shown in the patch format when stdin closes. 🦋

now, a single NUL byte can be written to stdin between raw input lines to compute file pair diffs up to that point — instead of waiting for stdin to close. and a NUL byte is also written to the output to delimit between these batches of diffs. so yes, it's batching. it's iconic. it's giving "streaming." 😭

using this command means the traditional diff pipeline can be broken up into separate stages where diff-pairs acts as the output phase. Other commands, such as diff-tree, may serve as a frontend to compute the raw diff format used as input. 🔥

instead of computing diffs via git diff-tree -p -M in one step, diff-tree can compute the file pairs and rename information without the blob diffs. Then you feed that output to diff-pairs to generate the underlying blob diffs, like this:

git diff-tree -z -r -M $a $b |
git diff-pairs -z

computing the tree diff upfront with rename information allows patch output from diff-pairs to be progressively computed over the course of potentially multiple invocations. main character energy, honestly. 👑

big warning energy: pathspecs are not currently supported by diff-pairs. Pathspec limiting should be performed by the upstream command generating the raw diffs used as input. so like, do it before, not here. 🙈
also: tree objects are not currently supported as input and are rejected. and abbreviated object IDs in the diff-pairs input are not supported. Outputted object IDs can be abbreviated using the --abbrev option though. 💅

🎀 OPTIONS 🎀

okay this is the big one. every single flag, no skips, let's go. 🌈

  • -p, -u, --patch — generate patch (peep the section called "GENERATING PATCH TEXT WITH -P").
  • -s, --no-patch — suppress all output from the diff machinery. super useful for commands like git show that show the patch by default and you want to squelch that, or to cancel out the effect of options like --patch, --stat that came earlier on the command line in an alias. ✨
  • -U<n>, --unified=<n> — generate diffs with <n> lines of context. The number of context lines defaults to diff.context or 3 if the configuration variable is unset. (fun fact: -U without <n> is silently accepted as a synonym for -p due to a historical accident 😭). Implies --patch.
  • --output=<file> — output to a specific file instead of stdout.
  • --output-indicator-new=<char>, --output-indicator-old=<char>, --output-indicator-context=<char> — specify the character used to indicate new, old or context lines in the generated patch. Normally they are +, - and ' ' respectively.
  • --raw — generate the diff in raw format. This is the default. 💖
  • --patch-with-raw — synonym for -p --raw.
  • --indent-heuristic — enable the heuristic that shifts diff hunk boundaries to make patches easier to read. This is the default. 🦋
  • --no-indent-heuristic — disable the indent heuristic.
  • --minimal — spend extra time to make sure the smallest possible diff is produced. perfectionism, but make it computational.
  • --patience — generate a diff using the "patience diff" algorithm.
  • --histogram — generate a diff using the "histogram diff" algorithm.
  • --anchored=<text> — 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 <text>, this algorithm attempts to prevent it from appearing as a deletion or addition in the output. It uses the "patience diff" algorithm internally. 🎀
  • --diff-algorithm=(patience|minimal|histogram|myers) — 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. iykyk 💅

  • --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 or by setting diff.statNameWidth=<name-width>. The width of the graph part can be limited by using --stat-graph-width=<graph-width> or by setting diff.statGraphWidth=<graph-width>. Using --stat or --stat-graph-width affects all commands generating a stat graph, while setting diff.statNameWidth or diff.statGraphWidth 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>. 😮‍💨 that was a lot, but we got through it together.
  • --compact-summary — 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.
  • --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.
  • -X [<param>,...], --dirstat[=<param>,...] — 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. 🍓

  • --cumulative — synonym for --dirstat=cumulative.
  • --dirstat-by-file[=<param>,...] — synonym for --dirstat=files,<param>,....
  • --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, pathnames with "unusual" characters are quoted as explained for the configuration variable core.quotePath (see git-config(1)). 🌸
  • --name-only — show only the name of each changed file in the post-image tree. The file names are often encoded in UTF-8. For more information see the discussion about encoding in the git-log(1) manual page.
  • --name-status — show only the name(s) and status of each changed file. See the description of the --diff-filter option on what the status letters mean. Just like --name-only the file names are often encoded in UTF-8.
  • --submodule[=<format>] — 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. 🧚
  • --color[=<when>] — show colored diff. --color (i.e. without =<when>) is the same as --color=always. <when> can be one of always, never, or auto. 🌈
  • --no-color — turn off colored diff. It is the same as --color=never.
  • --color-moved[=<mode>] — moved lines of code get their own little colour moment ✨ the way that a block of code just picks up and moves and the diff is like "bestie I see you". The <mode> defaults to no if you don't give the option at all, and to zebra if you give the option with no mode attached. The mode has to be one of these cuties:
    • no — moved lines are not highlighted. simple as that 💅
    • default — a synonym for zebra. heads up: this may change to a more sensible mode in the future, so don't get too attached.
    • plain — any line that's added in one place and was removed in another place gets painted with color.diff.newMoved, and similarly color.diff.oldMoved gets used for removed lines that show up added somewhere else in the diff. this mode picks up any moved line, but ngl it's not very useful in a review when you're trying to figure out if a block of code moved without permutation.
    • blocks — blocks of moved text of at least 20 alphanumeric characters get detected greedily 🔥 the detected blocks are painted using either the color.diff.(old|new)Moved colour. adjacent blocks cannot be told apart, so like… they blend, rip.
    • zebra — blocks of moved text are detected as in blocks mode, but the blocks get painted using either the color.diff.(old|new)Moved colour or color.diff.(old|new)MovedAlternative. the change between the two colours indicates that a new block was detected — stripes, hence the name, iconic 🦓
    • dimmed-zebra — similar to zebra, but it also does extra dimming of the uninteresting parts of moved code. the bordering lines of two adjacent blocks are considered interesting, the rest is uninteresting. dimmed_zebra is a deprecated synonym.
  • --no-color-moved — turn off move detection entirely. this can be used to override configuration settings. it's the exact same thing as --color-moved=no.
  • --color-moved-ws=<mode>,... — this configures how whitespace is ignored when performing the move detection for --color-moved. these modes can be given as a comma separated list:
    • no — do not ignore whitespace when performing move detection.
    • ignore-space-at-eol — ignore changes in whitespace at EOL.
    • 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.
    • ignore-all-space — ignore whitespace when comparing lines. this ignores differences even if one line has whitespace where the other line has none.
    • allow-indentation-change — 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 one is incompatible with the other modes 🫶
  • --no-color-moved-ws — do not ignore whitespace when performing move detection. this can be used to override configuration settings. it's the same as --color-moved-ws=no.
  • --word-diff[=<mode>] — okay so 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}. it 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 💖

the --word-diff option operates by taking the same line-by-line diff that is produced without the option and computing word-by-word changes within each hunk. this may produce a larger diff than a dedicated word-diff tool would. if Git acquires a different implementation in the future, the output may change. note that this is similar to the --diff-algorithm option, which may also change the output. (so like, don't hardcode your life around it, yk?)

  • --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. 🫠

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. (priority order bestie, respect it 👑)

  • --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. sometimes you just want the chaos, honestly.
  • --rename-empty, --no-rename-empty — whether to use empty blobs as rename source.
  • --check — warn if changes introduce conflict markers or whitespace errors. what counts as whitespace errors is controlled by the 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 — pick a lane babes.
  • --ws-error-highlight=<kind> — highlight whitespace errors in the context, old or new lines of the diff. multiple values are separated by comma, none resets previous values, default resets 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. ✨
  • --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. no more guessing games 💅
  • --binary — in addition to --full-index, output a binary diff that can be applied with git-apply. implies --patch.
  • --abbrev[=<n>] — 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>.
  • -B[<n>][/<m>], --break-rewrites[=[<n>][/<m>]] — break complete rewrite changes into pairs of delete and create. this serves two purposes, bestie, listen up:
    • 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%. the default similarity index is 50%. math girlies rise 🙈
  • -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, the -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 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. irreversible, babes. one way street. 💀

when used together with -B, omit also the preimage in the deletion part of a delete/create pair.

  • -l<num> — okay so this one is a little performance bodyguard for the rename/copy detectors. The -M and -C options do some cheap preliminary passes to sniff out subsets of renames/copies, and then there's an exhaustive fallback that compares all remaining unpaired destinations against all relevant sources (for renames, only the leftover unpaired sources matter; for copies, every original source matters). For N sources and destinations, that exhaustive check is O(N^2) — so yeah, it can get spendy. This option straight-up stops the exhaustive portion from running if the number of source/destination files involved goes over <num>. Defaults to diff.renameLimit. And bestie, note: a value of 0 is treated as unlimited. 💅
  • --diff-filter=[(A|C|D|M|R|T|U|X|B)...[*]] — the VIP list for which files get to show up. You pick files that are Added (A), Copied (C), Deleted (D), Modified (M), Renamed (R), have their type changed (T) (like regular file, symlink, submodule, ...), are Unmerged (U), are Unknown (X), or have had their pairing Broken (B). Any combination of those filter characters (including none) is fair game. When you add * (the All-or-none one) to the combo, all paths get selected if there's any file that matches other criteria in the comparison — but if no file matches the other criteria, nothing gets selected. 🎀

Also you can downcase the upper-case letters to exclude. Like --diff-filter=ad excludes added and deleted paths. 🙈

Note that not all diffs can feature all types — for instance, copied and renamed entries cannot appear if detection for those types is disabled.

  • -S<string> — 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, ngl. It's genuinely iconic when you're hunting for an exact block of code (like a struct) and wanna 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.
  • -G<regex> — 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.

  • --find-object=<object-id> — 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. 🌸
  • --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>. It's giving main character energy for the whole changeset 💅.
  • --pickaxe-regex — treat the <string> given to -S as an extended POSIX regular expression to match. 🧚
  • -O<orderfile> — 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". 🦋

  • --skip-to=<file>, --rotate-to=<file> — 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 options were invented primarily for the use of the git difftool command, and may not be very useful otherwise. No cap, that's literally what the docs say 🙈.
  • -R — swap two inputs; that is, show differences from index or on-disk file to tree contents. 🔄
  • --relative[=<path>], --no-relative — 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're 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 the diff.relative config option and a previous --relative.
  • -a, --text — treat all files as text. Simple as that ✨.
  • --ignore-cr-at-eol — ignore carriage-return at the end of line when doing a comparison.
  • --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. Maximum chaos tolerance 🫶.
  • --ignore-blank-lines — ignore changes whose lines are all blank.
  • -I<regex>, --ignore-matching-lines=<regex> — ignore changes whose all lines match <regex>. This option may be specified more than once. 🌈
  • --inter-hunk-context=<number> — 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.
  • -W, --function-context — 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)). Whole function or nothing, honey 👑.
  • --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. Perfect for scripting bestie 💖.
  • --quiet — disable all output of the program. Implies --exit-code. Disables execution of external diff helpers whose exit code is not trusted, i.e. their respective configuration option diff.trustExitCode or diff.<driver>.trustExitCode or environment variable GIT_EXTERNAL_DIFF_TRUST_EXIT_CODE is false. 🤫
  • --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[=(none|untracked|dirty|all)] — ignore changes to submodules in the diff generation. all 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.
  • --default-prefix — use the default source and destination prefixes ("a/" and "b/"). This overrides configuration variables such as diff.noprefix, diff.srcPrefix, diff.dstPrefix, and diff.mnemonicPrefix (see git-config(1)). ✨
  • --line-prefix=<prefix> — prepend an additional <prefix> to every line of output. 💫
  • --ita-invisible-in-index — 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 👀.
  • --max-depth=<depth> — for each pathspec given on command line, descend at most <depth> levels of directories. A value of -1 means no limit. Cannot be combined with wildcards in the pathspec. Given a tree containing foo/bar/baz, the following list shows the matches generated by each set of options:
    • --max-depth=0 -- foo: foo
    • --max-depth=1 -- foo: foo/bar
    • --max-depth=1 -- foo/bar: foo/bar/baz
    • --max-depth=1 -- foo foo/bar: foo/bar/baz
    • --max-depth=2 -- foo: foo/bar/baz 🍓

If no pathspec is given, the depth is measured as if all top-level entries were specified. Heads up though — that's not the same as measuring from the root, because --max-depth=0 would still hand you foo. Which is actually the whole point: it lets you still cap the depth while asking for just a subset of the top-level entries. 💅

Lowkey important: this option is only supported for diffs between tree objects — not against the index, and not against the working tree. No cap. 🙈

For the full tea on these common options, go peek at gitdiffcore(7) too. 🫶

✨ GENERATING PATCH TEXT WITH -P ✨

Okay so when you run 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, it produces patch text. And you can customize how that patch text gets made via the GIT_EXTERNAL_DIFF and GIT_DIFF_OPTS environment variables (peep git(1) for those), and via the diff attribute (peep gitattributes(5)). 🎀

What -p produces is slightly different from the traditional diff format, and here's the rundown:

  1. It's preceded by 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. And like, especially — even for a creation or a deletion, /dev/null is not used in place of the a/ or b/ filenames.

When a 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 the rename/copy produces, respectively.

  1. It's 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 <mode> 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's a rounded-down integer followed by a percent sign. So a similarity index of 100% is reserved for two equal files, while 100% dissimilarity means that literally 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 doesn't change; otherwise, separate lines indicate the old and the new mode.

  1. Pathnames with "unusual" characters are quoted as explained for the configuration variable core.quotePath (see git-config(1)).
  2. 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. Like, 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
  1. Hunk headers mention the name of the function to which the hunk applies. See "Defining a custom hunk-header" in gitattributes(5) for the deets on how to tailor this to specific languages. 🦋

🌈 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). Also note that you can give a suitable --diff-merges option to any of these commands to force generation of diffs in a 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);
  1. It's preceded by 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
  1. It's 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 info about detected content movement (rename and copy detection) are designed to work with the diff of two <tree-ish> and are not used by combined diff format.

  1. It's followed by a two-line from-file/to-file header:
--- a/file
+++ b/file

Similar to the two-line header for the traditional unified diff format, /dev/null is used to signal created or deleted files.

But wait — if the --combined-all-paths option is provided, then instead of a two-line from-file/to-file you get an 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, letting you see the original name of the file in different parents. 👑

  1. 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 the line appears in the result, and fileN doesn't have that line (in other words, the line was added, from the point of view of that parent).

In the example output above, 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"). 🫶

⭐ GIT ⭐

Part of the git(1) suite. Obviously. 💖

And that's a wrap bestie!! 🎀 This whole iconic page is from Git 2.56.0, dated 2026-09-27, and it's the GIT-DIFF-PAIRS(1) manual — go forth and diff slayfully. ✨👑

📦 where this page comes from