Do a cross-project merge of Paul Mackerras' gitk visualizer
[git/git.git] / Documentation / diff-format.txt
1 The output format from "git-diff-cache", "git-diff-tree" and
2 "git-diff-files" is very similar.
3
4 These commands all compare two sets of things; what are
5 compared are different:
6
7 git-diff-cache <tree-ish>::
8 compares the <tree-ish> and the files on the filesystem.
9
10 git-diff-cache --cached <tree-ish>::
11 compares the <tree-ish> and the cache.
12
13 git-diff-tree [-r] <tree-ish-1> <tree-ish-2> [<pattern>...]::
14 compares the trees named by the two arguments.
15
16 git-diff-files [<pattern>...]::
17 compares the cache and the files on the filesystem.
18
19
20 An output line is formatted this way:
21
22 in-place edit :100644 100644 bcd1234... 0123456... M file0
23 copy-edit :100644 100644 abcd123... 1234567... C68 file1 file2
24 rename-edit :100644 100644 abcd123... 1234567... R86 file1 file3
25 create :000000 100644 0000000... 1234567... N file4
26 delete :100644 000000 1234567... 0000000... D file5
27 unmerged :000000 000000 0000000... 0000000... U file6
28
29 That is, from the left to the right:
30
31 (1) a colon.
32 (2) mode for "src"; 000000 if creation or unmerged.
33 (3) a space.
34 (4) mode for "dst"; 000000 if deletion or unmerged.
35 (5) a space.
36 (6) sha1 for "src"; 0{40} if creation or unmerged.
37 (7) a space.
38 (8) sha1 for "dst"; 0{40} if creation, unmerged or "look at work tree".
39 (9) a space.
40 (10) status, followed by optional "score" number.
41 (11) a tab or a NUL when '-z' option is used.
42 (12) path for "src"
43 (13) a tab or a NUL when '-z' option is used; only exists for C or R.
44 (14) path for "dst"; only exists for C or R.
45 (15) an LF or a NUL when '-z' option is used, to terminate the record.
46
47 <sha1> is shown as all 0's if new is a file on the filesystem
48 and it is out of sync with the cache. Example:
49
50 :100644 100644 5be4a4...... 000000...... M file.c
51
52 Generating patches with -p
53 --------------------------
54
55 When "git-diff-cache", "git-diff-tree", or "git-diff-files" are run
56 with a '-p' option, they do not produce the output described above;
57 instead they produce a patch file.
58
59 The patch generation can be customized at two levels. This
60 customization also applies to "git-diff-helper".
61
62 1. When the environment variable 'GIT_EXTERNAL_DIFF' is not set,
63 these commands internally invoke "diff" like this:
64
65 diff -L a/<path> -L a/<path> -pu <old> <new>
66 +
67 For added files, `/dev/null` is used for <old>. For removed
68 files, `/dev/null` is used for <new>
69 +
70 The "diff" formatting options can be customized via the
71 environment variable 'GIT_DIFF_OPTS'. For example, if you
72 prefer context diff:
73
74 GIT_DIFF_OPTS=-c git-diff-cache -p $(cat .git/HEAD)
75
76
77 2. When the environment variable 'GIT_EXTERNAL_DIFF' is set, the
78 program named by it is called, instead of the diff invocation
79 described above.
80 +
81 For a path that is added, removed, or modified,
82 'GIT_EXTERNAL_DIFF' is called with 7 parameters:
83
84 path old-file old-hex old-mode new-file new-hex new-mode
85 +
86 where:
87
88 <old|new>-file:: are files GIT_EXTERNAL_DIFF can use to read the
89 contents of <old|ne>,
90 <old|new>-hex:: are the 40-hexdigit SHA1 hashes,
91 <old|new>-mode:: are the octal representation of the file modes.
92
93 +
94 The file parameters can point at the user's working file
95 (e.g. `new-file` in "git-diff-files"), `/dev/null` (e.g. `old-file`
96 when a new file is added), or a temporary file (e.g. `old-file` in the
97 cache). 'GIT_EXTERNAL_DIFF' should not worry about unlinking the
98 temporary file --- it is removed when 'GIT_EXTERNAL_DIFF' exits.
99
100 For a path that is unmerged, 'GIT_EXTERNAL_DIFF' is called with 1
101 parameter, <path>.
102
103
104 Git specific extention to diff format
105 -------------------------------------
106
107 What -p option produces is slightly different from the
108 traditional diff format.
109
110 (1) It is preceeded with a "git diff" header, that looks like
111 this:
112
113 diff --git a/file1 b/file2
114
115 The a/ and b/ filenames are the same unless rename/copy is
116 involved. Especially, even for a creation or a deletion,
117 /dev/null is _not_ used in place of a/ or b/ filename.
118
119 When rename/copy is involved, file1 and file2 shows the
120 name of the source file of the rename/copy and the name of
121 the file that rename/copy produces, respectively.
122
123 (2) It is followed by extended header lines that are one or
124 more of:
125
126 old mode <mode>
127 new mode <mode>
128 deleted file mode <mode>
129 new file mode <mode>
130 copy from <path>
131 copy to <path>
132 rename from <path>
133 rename to <path>
134 similarity index <number>
135 dissimilarity index <number>