1GIT-DIFF-INDEX(1)                 Git Manual                 GIT-DIFF-INDEX(1)
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3
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NAME

6       git-diff-index - Compares content and mode of blobs between the index
7       and repository
8

SYNOPSIS

10       git diff-index [-m] [--cached] [<common diff options>] <tree-ish> [<path>...]
11
12

DESCRIPTION

14       Compares the content and mode of the blobs found via a tree object with
15       the content of the current index and, optionally ignoring the stat
16       state of the file on disk. When paths are specified, compares only
17       those named paths. Otherwise all entries in the index are compared.
18

OPTIONS

20       -p, -u, --patch
21           Generate patch (see section on generating patches).
22
23       -U<n>, --unified=<n>
24           Generate diffs with <n> lines of context instead of the usual
25           three. Implies -p.
26
27       --raw
28           Generate the raw format. This is the default.
29
30       --patch-with-raw
31           Synonym for -p --raw.
32
33       --minimal
34           Spend extra time to make sure the smallest possible diff is
35           produced.
36
37       --patience
38           Generate a diff using the "patience diff" algorithm.
39
40       --histogram
41           Generate a diff using the "histogram diff" algorithm.
42
43       --diff-algorithm={patience|minimal|histogram|myers}
44           Choose a diff algorithm. The variants are as follows:
45
46           default, myers
47               The basic greedy diff algorithm. Currently, this is the
48               default.
49
50           minimal
51               Spend extra time to make sure the smallest possible diff is
52               produced.
53
54           patience
55               Use "patience diff" algorithm when generating patches.
56
57           histogram
58               This algorithm extends the patience algorithm to "support
59               low-occurrence common elements".
60
61           For instance, if you configured diff.algorithm variable to a
62           non-default value and want to use the default one, then you have to
63           use --diff-algorithm=default option.
64
65       --stat[=<width>[,<name-width>[,<count>]]]
66           Generate a diffstat. By default, as much space as necessary will be
67           used for the filename part, and the rest for the graph part.
68           Maximum width defaults to terminal width, or 80 columns if not
69           connected to a terminal, and can be overridden by <width>. The
70           width of the filename part can be limited by giving another width
71           <name-width> after a comma. The width of the graph part can be
72           limited by using --stat-graph-width=<width> (affects all commands
73           generating a stat graph) or by setting diff.statGraphWidth=<width>
74           (does not affect git format-patch). By giving a third parameter
75           <count>, you can limit the output to the first <count> lines,
76           followed by ...  if there are more.
77
78           These parameters can also be set individually with
79           --stat-width=<width>, --stat-name-width=<name-width> and
80           --stat-count=<count>.
81
82       --numstat
83           Similar to --stat, but shows number of added and deleted lines in
84           decimal notation and pathname without abbreviation, to make it more
85           machine friendly. For binary files, outputs two - instead of saying
86           0 0.
87
88       --shortstat
89           Output only the last line of the --stat format containing total
90           number of modified files, as well as number of added and deleted
91           lines.
92
93       --dirstat[=<param1,param2,...>]
94           Output the distribution of relative amount of changes for each
95           sub-directory. The behavior of --dirstat can be customized by
96           passing it a comma separated list of parameters. The defaults are
97           controlled by the diff.dirstat configuration variable (see git-
98           config(1)). The following parameters are available:
99
100           changes
101               Compute the dirstat numbers by counting the lines that have
102               been removed from the source, or added to the destination. This
103               ignores the amount of pure code movements within a file. In
104               other words, rearranging lines in a file is not counted as much
105               as other changes. This is the default behavior when no
106               parameter is given.
107
108           lines
109               Compute the dirstat numbers by doing the regular line-based
110               diff analysis, and summing the removed/added line counts. (For
111               binary files, count 64-byte chunks instead, since binary files
112               have no natural concept of lines). This is a more expensive
113               --dirstat behavior than the changes behavior, but it does count
114               rearranged lines within a file as much as other changes. The
115               resulting output is consistent with what you get from the other
116               --*stat options.
117
118           files
119               Compute the dirstat numbers by counting the number of files
120               changed. Each changed file counts equally in the dirstat
121               analysis. This is the computationally cheapest --dirstat
122               behavior, since it does not have to look at the file contents
123               at all.
124
125           cumulative
126               Count changes in a child directory for the parent directory as
127               well. Note that when using cumulative, the sum of the
128               percentages reported may exceed 100%. The default
129               (non-cumulative) behavior can be specified with the
130               noncumulative parameter.
131
132           <limit>
133               An integer parameter specifies a cut-off percent (3% by
134               default). Directories contributing less than this percentage of
135               the changes are not shown in the output.
136
137           Example: The following will count changed files, while ignoring
138           directories with less than 10% of the total amount of changed
139           files, and accumulating child directory counts in the parent
140           directories: --dirstat=files,10,cumulative.
141
142       --summary
143           Output a condensed summary of extended header information such as
144           creations, renames and mode changes.
145
146       --patch-with-stat
147           Synonym for -p --stat.
148
149       -z
150           When --raw, --numstat, --name-only or --name-status has been given,
151           do not munge pathnames and use NULs as output field terminators.
152
153           Without this option, each pathname output will have TAB, LF, double
154           quotes, and backslash characters replaced with \t, \n, \", and \\,
155           respectively, and the pathname will be enclosed in double quotes if
156           any of those replacements occurred.
157
158       --name-only
159           Show only names of changed files.
160
161       --name-status
162           Show only names and status of changed files. See the description of
163           the --diff-filter option on what the status letters mean.
164
165       --submodule[=<format>]
166           Specify how differences in submodules are shown. When --submodule
167           or --submodule=log is given, the log format is used. This format
168           lists the commits in the range like git-submodule(1)summary does.
169           Omitting the --submodule option or specifying --submodule=short,
170           uses the short format. This format just shows the names of the
171           commits at the beginning and end of the range. Can be tweaked via
172           the diff.submodule configuration variable.
173
174       --color[=<when>]
175           Show colored diff.  --color (i.e. without =<when>) is the same as
176           --color=always.  <when> can be one of always, never, or auto.
177
178       --no-color
179           Turn off colored diff. It is the same as --color=never.
180
181       --word-diff[=<mode>]
182           Show a word diff, using the <mode> to delimit changed words. By
183           default, words are delimited by whitespace; see --word-diff-regex
184           below. The <mode> defaults to plain, and must be one of:
185
186           color
187               Highlight changed words using only colors. Implies --color.
188
189           plain
190               Show words as [-removed-] and {+added+}. Makes no attempts to
191               escape the delimiters if they appear in the input, so the
192               output may be ambiguous.
193
194           porcelain
195               Use a special line-based format intended for script
196               consumption. Added/removed/unchanged runs are printed in the
197               usual unified diff format, starting with a +/-/` ` character at
198               the beginning of the line and extending to the end of the line.
199               Newlines in the input are represented by a tilde ~ on a line of
200               its own.
201
202           none
203               Disable word diff again.
204
205           Note that despite the name of the first mode, color is used to
206           highlight the changed parts in all modes if enabled.
207
208       --word-diff-regex=<regex>
209           Use <regex> to decide what a word is, instead of considering runs
210           of non-whitespace to be a word. Also implies --word-diff unless it
211           was already enabled.
212
213           Every non-overlapping match of the <regex> is considered a word.
214           Anything between these matches is considered whitespace and
215           ignored(!) for the purposes of finding differences. You may want to
216           append |[^[:space:]] to your regular expression to make sure that
217           it matches all non-whitespace characters. A match that contains a
218           newline is silently truncated(!) at the newline.
219
220           The regex can also be set via a diff driver or configuration
221           option, see gitattributes(1) or git-config(1). Giving it explicitly
222           overrides any diff driver or configuration setting. Diff drivers
223           override configuration settings.
224
225       --color-words[=<regex>]
226           Equivalent to --word-diff=color plus (if a regex was specified)
227           --word-diff-regex=<regex>.
228
229       --no-renames
230           Turn off rename detection, even when the configuration file gives
231           the default to do so.
232
233       --check
234           Warn if changes introduce whitespace errors. What are considered
235           whitespace errors is controlled by core.whitespace configuration.
236           By default, trailing whitespaces (including lines that solely
237           consist of whitespaces) and a space character that is immediately
238           followed by a tab character inside the initial indent of the line
239           are considered whitespace errors. Exits with non-zero status if
240           problems are found. Not compatible with --exit-code.
241
242       --full-index
243           Instead of the first handful of characters, show the full pre- and
244           post-image blob object names on the "index" line when generating
245           patch format output.
246
247       --binary
248           In addition to --full-index, output a binary diff that can be
249           applied with git-apply.
250
251       --abbrev[=<n>]
252           Instead of showing the full 40-byte hexadecimal object name in
253           diff-raw format output and diff-tree header lines, show only a
254           partial prefix. This is independent of the --full-index option
255           above, which controls the diff-patch output format. Non default
256           number of digits can be specified with --abbrev=<n>.
257
258       -B[<n>][/<m>], --break-rewrites[=[<n>][/<m>]]
259           Break complete rewrite changes into pairs of delete and create.
260           This serves two purposes:
261
262           It affects the way a change that amounts to a total rewrite of a
263           file not as a series of deletion and insertion mixed together with
264           a very few lines that happen to match textually as the context, but
265           as a single deletion of everything old followed by a single
266           insertion of everything new, and the number m controls this aspect
267           of the -B option (defaults to 60%).  -B/70% specifies that less
268           than 30% of the original should remain in the result for Git to
269           consider it a total rewrite (i.e. otherwise the resulting patch
270           will be a series of deletion and insertion mixed together with
271           context lines).
272
273           When used with -M, a totally-rewritten file is also considered as
274           the source of a rename (usually -M only considers a file that
275           disappeared as the source of a rename), and the number n controls
276           this aspect of the -B option (defaults to 50%).  -B20% specifies
277           that a change with addition and deletion compared to 20% or more of
278           the file’s size are eligible for being picked up as a possible
279           source of a rename to another file.
280
281       -M[<n>], --find-renames[=<n>]
282           Detect renames. If n is specified, it is a threshold on the
283           similarity index (i.e. amount of addition/deletions compared to the
284           file’s size). For example, -M90% means Git should consider a
285           delete/add pair to be a rename if more than 90% of the file hasn’t
286           changed. Without a % sign, the number is to be read as a fraction,
287           with a decimal point before it. I.e., -M5 becomes 0.5, and is thus
288           the same as -M50%. Similarly, -M05 is the same as -M5%. To limit
289           detection to exact renames, use -M100%.
290
291       -C[<n>], --find-copies[=<n>]
292           Detect copies as well as renames. See also --find-copies-harder. If
293           n is specified, it has the same meaning as for -M<n>.
294
295       --find-copies-harder
296           For performance reasons, by default, -C option finds copies only if
297           the original file of the copy was modified in the same changeset.
298           This flag makes the command inspect unmodified files as candidates
299           for the source of copy. This is a very expensive operation for
300           large projects, so use it with caution. Giving more than one -C
301           option has the same effect.
302
303       -D, --irreversible-delete
304           Omit the preimage for deletes, i.e. print only the header but not
305           the diff between the preimage and /dev/null. The resulting patch is
306           not meant to be applied with patch nor git apply; this is solely
307           for people who want to just concentrate on reviewing the text after
308           the change. In addition, the output obviously lack enough
309           information to apply such a patch in reverse, even manually, hence
310           the name of the option.
311
312           When used together with -B, omit also the preimage in the deletion
313           part of a delete/create pair.
314
315       -l<num>
316           The -M and -C options require O(n^2) processing time where n is the
317           number of potential rename/copy targets. This option prevents
318           rename/copy detection from running if the number of rename/copy
319           targets exceeds the specified number.
320
321       --diff-filter=[(A|C|D|M|R|T|U|X|B)...[*]]
322           Select only files that are Added (A), Copied (C), Deleted (D),
323           Modified (M), Renamed (R), have their type (i.e. regular file,
324           symlink, submodule, ...) changed (T), are Unmerged (U), are Unknown
325           (X), or have had their pairing Broken (B). Any combination of the
326           filter characters (including none) can be used. When *
327           (All-or-none) is added to the combination, all paths are selected
328           if there is any file that matches other criteria in the comparison;
329           if there is no file that matches other criteria, nothing is
330           selected.
331
332       -S<string>
333           Look for differences that introduce or remove an instance of
334           <string>. Note that this is different than the string simply
335           appearing in diff output; see the pickaxe entry in gitdiffcore(7)
336           for more details.
337
338       -G<regex>
339           Look for differences whose added or removed line matches the given
340           <regex>.
341
342       --pickaxe-all
343           When -S or -G finds a change, show all the changes in that
344           changeset, not just the files that contain the change in <string>.
345
346       --pickaxe-regex
347           Make the <string> not a plain string but an extended POSIX regex to
348           match.
349
350       -O<orderfile>
351           Output the patch in the order specified in the <orderfile>, which
352           has one shell glob pattern per line.
353
354       -R
355           Swap two inputs; that is, show differences from index or on-disk
356           file to tree contents.
357
358       --relative[=<path>]
359           When run from a subdirectory of the project, it can be told to
360           exclude changes outside the directory and show pathnames relative
361           to it with this option. When you are not in a subdirectory (e.g. in
362           a bare repository), you can name which subdirectory to make the
363           output relative to by giving a <path> as an argument.
364
365       -a, --text
366           Treat all files as text.
367
368       --ignore-space-at-eol
369           Ignore changes in whitespace at EOL.
370
371       -b, --ignore-space-change
372           Ignore changes in amount of whitespace. This ignores whitespace at
373           line end, and considers all other sequences of one or more
374           whitespace characters to be equivalent.
375
376       -w, --ignore-all-space
377           Ignore whitespace when comparing lines. This ignores differences
378           even if one line has whitespace where the other line has none.
379
380       --inter-hunk-context=<lines>
381           Show the context between diff hunks, up to the specified number of
382           lines, thereby fusing hunks that are close to each other.
383
384       -W, --function-context
385           Show whole surrounding functions of changes.
386
387       --exit-code
388           Make the program exit with codes similar to diff(1). That is, it
389           exits with 1 if there were differences and 0 means no differences.
390
391       --quiet
392           Disable all output of the program. Implies --exit-code.
393
394       --ext-diff
395           Allow an external diff helper to be executed. If you set an
396           external diff driver with gitattributes(5), you need to use this
397           option with git-log(1) and friends.
398
399       --no-ext-diff
400           Disallow external diff drivers.
401
402       --textconv, --no-textconv
403           Allow (or disallow) external text conversion filters to be run when
404           comparing binary files. See gitattributes(5) for details. Because
405           textconv filters are typically a one-way conversion, the resulting
406           diff is suitable for human consumption, but cannot be applied. For
407           this reason, textconv filters are enabled by default only for git-
408           diff(1) and git-log(1), but not for git-format-patch(1) or diff
409           plumbing commands.
410
411       --ignore-submodules[=<when>]
412           Ignore changes to submodules in the diff generation. <when> can be
413           either "none", "untracked", "dirty" or "all", which is the default.
414           Using "none" will consider the submodule modified when it either
415           contains untracked or modified files or its HEAD differs from the
416           commit recorded in the superproject and can be used to override any
417           settings of the ignore option in git-config(1) or gitmodules(5).
418           When "untracked" is used submodules are not considered dirty when
419           they only contain untracked content (but they are still scanned for
420           modified content). Using "dirty" ignores all changes to the work
421           tree of submodules, only changes to the commits stored in the
422           superproject are shown (this was the behavior until 1.7.0). Using
423           "all" hides all changes to submodules.
424
425       --src-prefix=<prefix>
426           Show the given source prefix instead of "a/".
427
428       --dst-prefix=<prefix>
429           Show the given destination prefix instead of "b/".
430
431       --no-prefix
432           Do not show any source or destination prefix.
433
434       For more detailed explanation on these common options, see also
435       gitdiffcore(7).
436
437       <tree-ish>
438           The id of a tree object to diff against.
439
440       --cached
441           do not consider the on-disk file at all
442
443       -m
444           By default, files recorded in the index but not checked out are
445           reported as deleted. This flag makes git diff-index say that all
446           non-checked-out files are up to date.
447

RAW OUTPUT FORMAT

449       The raw output format from "git-diff-index", "git-diff-tree",
450       "git-diff-files" and "git diff --raw" are very similar.
451
452       These commands all compare two sets of things; what is compared
453       differs:
454
455       git-diff-index <tree-ish>
456           compares the <tree-ish> and the files on the filesystem.
457
458       git-diff-index --cached <tree-ish>
459           compares the <tree-ish> and the index.
460
461       git-diff-tree [-r] <tree-ish-1> <tree-ish-2> [<pattern>...]
462           compares the trees named by the two arguments.
463
464       git-diff-files [<pattern>...]
465           compares the index and the files on the filesystem.
466
467       The "git-diff-tree" command begins its output by printing the hash of
468       what is being compared. After that, all the commands print one output
469       line per changed file.
470
471       An output line is formatted this way:
472
473           in-place edit  :100644 100644 bcd1234... 0123456... M file0
474           copy-edit      :100644 100644 abcd123... 1234567... C68 file1 file2
475           rename-edit    :100644 100644 abcd123... 1234567... R86 file1 file3
476           create         :000000 100644 0000000... 1234567... A file4
477           delete         :100644 000000 1234567... 0000000... D file5
478           unmerged       :000000 000000 0000000... 0000000... U file6
479
480
481       That is, from the left to the right:
482
483        1. a colon.
484
485        2. mode for "src"; 000000 if creation or unmerged.
486
487        3. a space.
488
489        4. mode for "dst"; 000000 if deletion or unmerged.
490
491        5. a space.
492
493        6. sha1 for "src"; 0{40} if creation or unmerged.
494
495        7. a space.
496
497        8. sha1 for "dst"; 0{40} if creation, unmerged or "look at work tree".
498
499        9. a space.
500
501       10. status, followed by optional "score" number.
502
503       11. a tab or a NUL when -z option is used.
504
505       12. path for "src"
506
507       13. a tab or a NUL when -z option is used; only exists for C or R.
508
509       14. path for "dst"; only exists for C or R.
510
511       15. an LF or a NUL when -z option is used, to terminate the record.
512
513       Possible status letters are:
514
515       ·   A: addition of a file
516
517       ·   C: copy of a file into a new one
518
519       ·   D: deletion of a file
520
521       ·   M: modification of the contents or mode of a file
522
523       ·   R: renaming of a file
524
525       ·   T: change in the type of the file
526
527       ·   U: file is unmerged (you must complete the merge before it can be
528           committed)
529
530       ·   X: "unknown" change type (most probably a bug, please report it)
531
532       Status letters C and R are always followed by a score (denoting the
533       percentage of similarity between the source and target of the move or
534       copy), and are the only ones to be so.
535
536       <sha1> is shown as all 0’s if a file is new on the filesystem and it is
537       out of sync with the index.
538
539       Example:
540
541           :100644 100644 5be4a4...... 000000...... M file.c
542
543
544       When -z option is not used, TAB, LF, and backslash characters in
545       pathnames are represented as \t, \n, and \\, respectively.
546

DIFF FORMAT FOR MERGES

548       "git-diff-tree", "git-diff-files" and "git-diff --raw" can take -c or
549       --cc option to generate diff output also for merge commits. The output
550       differs from the format described above in the following way:
551
552        1. there is a colon for each parent
553
554        2. there are more "src" modes and "src" sha1
555
556        3. status is concatenated status characters for each parent
557
558        4. no optional "score" number
559
560        5. single path, only for "dst"
561
562       Example:
563
564           ::100644 100644 100644 fabadb8... cc95eb0... 4866510... MM      describe.c
565
566
567       Note that combined diff lists only files which were modified from all
568       parents.
569

GENERATING PATCHES WITH -P

571       When "git-diff-index", "git-diff-tree", or "git-diff-files" are run
572       with a -p option, "git diff" without the --raw option, or "git log"
573       with the "-p" option, they do not produce the output described above;
574       instead they produce a patch file. You can customize the creation of
575       such patches via the GIT_EXTERNAL_DIFF and the GIT_DIFF_OPTS
576       environment variables.
577
578       What the -p option produces is slightly different from the traditional
579       diff format:
580
581        1. It is preceded with a "git diff" header that looks like this:
582
583               diff --git a/file1 b/file2
584
585           The a/ and b/ filenames are the same unless rename/copy is
586           involved. Especially, even for a creation or a deletion, /dev/null
587           is not used in place of the a/ or b/ filenames.
588
589           When rename/copy is involved, file1 and file2 show the name of the
590           source file of the rename/copy and the name of the file that
591           rename/copy produces, respectively.
592
593        2. It is followed by one or more extended header lines:
594
595               old mode <mode>
596               new mode <mode>
597               deleted file mode <mode>
598               new file mode <mode>
599               copy from <path>
600               copy to <path>
601               rename from <path>
602               rename to <path>
603               similarity index <number>
604               dissimilarity index <number>
605               index <hash>..<hash> <mode>
606
607           File modes are printed as 6-digit octal numbers including the file
608           type and file permission bits.
609
610           Path names in extended headers do not include the a/ and b/
611           prefixes.
612
613           The similarity index is the percentage of unchanged lines, and the
614           dissimilarity index is the percentage of changed lines. It is a
615           rounded down integer, followed by a percent sign. The similarity
616           index value of 100% is thus reserved for two equal files, while
617           100% dissimilarity means that no line from the old file made it
618           into the new one.
619
620           The index line includes the SHA-1 checksum before and after the
621           change. The <mode> is included if the file mode does not change;
622           otherwise, separate lines indicate the old and the new mode.
623
624        3. TAB, LF, double quote and backslash characters in pathnames are
625           represented as \t, \n, \" and \\, respectively. If there is need
626           for such substitution then the whole pathname is put in double
627           quotes.
628
629        4. All the file1 files in the output refer to files before the commit,
630           and all the file2 files refer to files after the commit. It is
631           incorrect to apply each change to each file sequentially. For
632           example, this patch will swap a and b:
633
634               diff --git a/a b/b
635               rename from a
636               rename to b
637               diff --git a/b b/a
638               rename from b
639               rename to a
640

COMBINED DIFF FORMAT

642       Any diff-generating command can take the ‘-c` or --cc option to produce
643       a combined diff when showing a merge. This is the default format when
644       showing merges with git-diff(1) or git-show(1). Note also that you can
645       give the `-m’ option to any of these commands to force generation of
646       diffs with individual parents of a merge.
647
648       A combined diff format looks like this:
649
650           diff --combined describe.c
651           index fabadb8,cc95eb0..4866510
652           --- a/describe.c
653           +++ b/describe.c
654           @@@ -98,20 -98,12 +98,20 @@@
655                   return (a_date > b_date) ? -1 : (a_date == b_date) ? 0 : 1;
656             }
657
658           - static void describe(char *arg)
659            -static void describe(struct commit *cmit, int last_one)
660           ++static void describe(char *arg, int last_one)
661             {
662            +      unsigned char sha1[20];
663            +      struct commit *cmit;
664                   struct commit_list *list;
665                   static int initialized = 0;
666                   struct commit_name *n;
667
668            +      if (get_sha1(arg, sha1) < 0)
669            +              usage(describe_usage);
670            +      cmit = lookup_commit_reference(sha1);
671            +      if (!cmit)
672            +              usage(describe_usage);
673            +
674                   if (!initialized) {
675                           initialized = 1;
676                           for_each_ref(get_name);
677
678
679
680        1. It is preceded with a "git diff" header, that looks like this (when
681           -c option is used):
682
683               diff --combined file
684
685           or like this (when --cc option is used):
686
687               diff --cc file
688
689        2. It is followed by one or more extended header lines (this example
690           shows a merge with two parents):
691
692               index <hash>,<hash>..<hash>
693               mode <mode>,<mode>..<mode>
694               new file mode <mode>
695               deleted file mode <mode>,<mode>
696
697           The mode <mode>,<mode>..<mode> line appears only if at least one of
698           the <mode> is different from the rest. Extended headers with
699           information about detected contents movement (renames and copying
700           detection) are designed to work with diff of two <tree-ish> and are
701           not used by combined diff format.
702
703        3. It is followed by two-line from-file/to-file header
704
705               --- a/file
706               +++ b/file
707
708           Similar to two-line header for traditional unified diff format,
709           /dev/null is used to signal created or deleted files.
710
711        4. Chunk header format is modified to prevent people from accidentally
712           feeding it to patch -p1. Combined diff format was created for
713           review of merge commit changes, and was not meant for apply. The
714           change is similar to the change in the extended index header:
715
716               @@@ <from-file-range> <from-file-range> <to-file-range> @@@
717
718           There are (number of parents + 1) @ characters in the chunk header
719           for combined diff format.
720
721       Unlike the traditional unified diff format, which shows two files A and
722       B with a single column that has - (minus — appears in A but removed in
723       B), + (plus — missing in A but added to B), or " " (space — unchanged)
724       prefix, this format compares two or more files file1, file2,... with
725       one file X, and shows how X differs from each of fileN. One column for
726       each of fileN is prepended to the output line to note how X’s line is
727       different from it.
728
729       A - character in the column N means that the line appears in fileN but
730       it does not appear in the result. A + character in the column N means
731       that the line appears in the result, and fileN does not have that line
732       (in other words, the line was added, from the point of view of that
733       parent).
734
735       In the above example output, the function signature was changed from
736       both files (hence two - removals from both file1 and file2, plus ++ to
737       mean one line that was added does not appear in either file1 nor
738       file2). Also eight other lines are the same from file1 but do not
739       appear in file2 (hence prefixed with +).
740
741       When shown by git diff-tree -c, it compares the parents of a merge
742       commit with the merge result (i.e. file1..fileN are the parents). When
743       shown by git diff-files -c, it compares the two unresolved merge
744       parents with the working tree file (i.e. file1 is stage 2 aka "our
745       version", file2 is stage 3 aka "their version").
746

OTHER DIFF FORMATS

748       The --summary option describes newly added, deleted, renamed and copied
749       files. The --stat option adds diffstat(1) graph to the output. These
750       options can be combined with other options, such as -p, and are meant
751       for human consumption.
752
753       When showing a change that involves a rename or a copy, --stat output
754       formats the pathnames compactly by combining common prefix and suffix
755       of the pathnames. For example, a change that moves arch/i386/Makefile
756       to arch/x86/Makefile while modifying 4 lines will be shown like this:
757
758           arch/{i386 => x86}/Makefile    |   4 +--
759
760
761       The --numstat option gives the diffstat(1) information but is designed
762       for easier machine consumption. An entry in --numstat output looks like
763       this:
764
765           1       2       README
766           3       1       arch/{i386 => x86}/Makefile
767
768
769       That is, from left to right:
770
771        1. the number of added lines;
772
773        2. a tab;
774
775        3. the number of deleted lines;
776
777        4. a tab;
778
779        5. pathname (possibly with rename/copy information);
780
781        6. a newline.
782
783       When -z output option is in effect, the output is formatted this way:
784
785           1       2       README NUL
786           3       1       NUL arch/i386/Makefile NUL arch/x86/Makefile NUL
787
788
789       That is:
790
791        1. the number of added lines;
792
793        2. a tab;
794
795        3. the number of deleted lines;
796
797        4. a tab;
798
799        5. a NUL (only exists if renamed/copied);
800
801        6. pathname in preimage;
802
803        7. a NUL (only exists if renamed/copied);
804
805        8. pathname in postimage (only exists if renamed/copied);
806
807        9. a NUL.
808
809       The extra NUL before the preimage path in renamed case is to allow
810       scripts that read the output to tell if the current record being read
811       is a single-path record or a rename/copy record without reading ahead.
812       After reading added and deleted lines, reading up to NUL would yield
813       the pathname, but if that is NUL, the record will show two paths.
814

OPERATING MODES

816       You can choose whether you want to trust the index file entirely (using
817       the --cached flag) or ask the diff logic to show any files that don’t
818       match the stat state as being "tentatively changed". Both of these
819       operations are very useful indeed.
820

CACHED MODE

822       If --cached is specified, it allows you to ask:
823
824           show me the differences between HEAD and the current index
825           contents (the ones I'd write using 'git write-tree')
826
827       For example, let’s say that you have worked on your working directory,
828       updated some files in the index and are ready to commit. You want to
829       see exactly what you are going to commit, without having to write a new
830       tree object and compare it that way, and to do that, you just do
831
832           git diff-index --cached HEAD
833
834       Example: let’s say I had renamed commit.c to git-commit.c, and I had
835       done an update-index to make that effective in the index file. git
836       diff-files wouldn’t show anything at all, since the index file matches
837       my working directory. But doing a git diff-index does:
838
839           torvalds@ppc970:~/git> git diff-index --cached HEAD
840           -100644 blob    4161aecc6700a2eb579e842af0b7f22b98443f74        commit.c
841           +100644 blob    4161aecc6700a2eb579e842af0b7f22b98443f74        git-commit.c
842
843       You can see easily that the above is a rename.
844
845       In fact, git diff-index --cached should always be entirely equivalent
846       to actually doing a git write-tree and comparing that. Except this one
847       is much nicer for the case where you just want to check where you are.
848
849       So doing a git diff-index --cached is basically very useful when you
850       are asking yourself "what have I already marked for being committed,
851       and what’s the difference to a previous tree".
852

NON-CACHED MODE

854       The "non-cached" mode takes a different approach, and is potentially
855       the more useful of the two in that what it does can’t be emulated with
856       a git write-tree + git diff-tree. Thus that’s the default mode. The
857       non-cached version asks the question:
858
859           show me the differences between HEAD and the currently checked out
860           tree - index contents _and_ files that aren't up-to-date
861
862       which is obviously a very useful question too, since that tells you
863       what you could commit. Again, the output matches the git diff-tree -r
864       output to a tee, but with a twist.
865
866       The twist is that if some file doesn’t match the index, we don’t have a
867       backing store thing for it, and we use the magic "all-zero" sha1 to
868       show that. So let’s say that you have edited kernel/sched.c, but have
869       not actually done a git update-index on it yet - there is no "object"
870       associated with the new state, and you get:
871
872           torvalds@ppc970:~/v2.6/linux> git diff-index --abbrev HEAD
873           :100644 100664 7476bb... 000000...      kernel/sched.c
874
875       i.e., it shows that the tree has changed, and that kernel/sched.c has
876       is not up-to-date and may contain new stuff. The all-zero sha1 means
877       that to get the real diff, you need to look at the object in the
878       working directory directly rather than do an object-to-object diff.
879
880           Note
881           As with other commands of this type, git diff-index does not
882           actually look at the contents of the file at all. So maybe
883           kernel/sched.c hasn’t actually changed, and it’s just that you
884           touched it. In either case, it’s a note that you need to git
885           update-index it to make the index be in sync.
886
887           Note
888           You can have a mixture of files show up as "has been updated" and
889           "is still dirty in the working directory" together. You can always
890           tell which file is in which state, since the "has been updated"
891           ones show a valid sha1, and the "not in sync with the index" ones
892           will always have the special all-zero sha1.
893

GIT

895       Part of the git(1) suite
896
897
898
899Git 1.8.3.1                       11/19/2018                 GIT-DIFF-INDEX(1)
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