Documentation: a few spelling fixes
[git/git.git] / Documentation / git-blame.txt
1 git-blame(1)
2 ============
3
4 NAME
5 ----
6 git-blame - Show what revision and author last modified each line of a file
7
8 SYNOPSIS
9 --------
10 [verse]
11 'git-blame' [-c] [-l] [-t] [-f] [-n] [-p] [-L n,m] [-S <revs-file>]
12 [-M] [-C] [-C] [--since=<date>] [<rev>] [--] <file>
13
14 DESCRIPTION
15 -----------
16
17 Annotates each line in the given file with information from the revision which
18 last modified the line. Optionally, start annotating from the given revision.
19
20 Also it can limit the range of lines annotated.
21
22 This report doesn't tell you anything about lines which have been deleted or
23 replaced; you need to use a tool such as gitlink:git-diff[1] or the "pickaxe"
24 interface briefly mentioned in the following paragraph.
25
26 Apart from supporting file annotation, git also supports searching the
27 development history for when a code snippet occurred in a change. This makes it
28 possible to track when a code snippet was added to a file, moved or copied
29 between files, and eventually deleted or replaced. It works by searching for
30 a text string in the diff. A small example:
31
32 -----------------------------------------------------------------------------
33 $ git log --pretty=oneline -S'blame_usage'
34 5040f17eba15504bad66b14a645bddd9b015ebb7 blame -S <ancestry-file>
35 ea4c7f9bf69e781dd0cd88d2bccb2bf5cc15c9a7 git-blame: Make the output
36 -----------------------------------------------------------------------------
37
38 OPTIONS
39 -------
40 -c, --compatibility::
41 Use the same output mode as gitlink:git-annotate[1] (Default: off).
42
43 -L n,m::
44 Annotate only the specified line range (lines count from 1).
45
46 -l, --long::
47 Show long rev (Default: off).
48
49 -t, --time::
50 Show raw timestamp (Default: off).
51
52 -S, --rev-file <revs-file>::
53 Use revs from revs-file instead of calling gitlink:git-rev-list[1].
54
55 -f, --show-name::
56 Show filename in the original commit. By default
57 filename is shown if there is any line that came from a
58 file with different name, due to rename detection.
59
60 -n, --show-number::
61 Show line number in the original commit (Default: off).
62
63 -p, --porcelain::
64 Show in a format designed for machine consumption.
65
66 -M::
67 Detect moving lines in the file as well. When a commit
68 moves a block of lines in a file (e.g. the original file
69 has A and then B, and the commit changes it to B and
70 then A), traditional 'blame' algorithm typically blames
71 the lines that were moved up (i.e. B) to the parent and
72 assigns blame to the lines that were moved down (i.e. A)
73 to the child commit. With this option, both groups of
74 lines are blamed on the parent.
75
76 -C::
77 In addition to `-M`, detect lines copied from other
78 files that were modified in the same commit. This is
79 useful when you reorganize your program and move code
80 around across files. When this option is given twice,
81 the command looks for copies from all other files in the
82 parent for the commit that creates the file in addition.
83
84 -h, --help::
85 Show help message.
86
87
88 THE PORCELAIN FORMAT
89 --------------------
90
91 In this format, each line is output after a header; the
92 header at the minimum has the first line which has:
93
94 - 40-byte SHA-1 of the commit the line is attributed to;
95 - the line number of the line in the original file;
96 - the line number of the line in the final file;
97 - on a line that starts a group of line from a different
98 commit than the previous one, the number of lines in this
99 group. On subsequent lines this field is absent.
100
101 This header line is followed by the following information
102 at least once for each commit:
103
104 - author name ("author"), email ("author-mail"), time
105 ("author-time"), and timezone ("author-tz"); similarly
106 for committer.
107 - filename in the commit the line is attributed to.
108 - the first line of the commit log message ("summary").
109
110 The contents of the actual line is output after the above
111 header, prefixed by a TAB. This is to allow adding more
112 header elements later.
113
114
115 SPECIFYING RANGES
116 -----------------
117
118 Unlike `git-blame` and `git-annotate` in older git, the extent
119 of annotation can be limited to both line ranges and revision
120 ranges. When you are interested in finding the origin for
121 ll. 40-60 for file `foo`, you can use `-L` option like this:
122
123 git blame -L 40,60 foo
124
125 Also you can use regular expression to specify the line range.
126
127 git blame -L '/^sub hello {/,/^}$/' foo
128
129 would limit the annotation to the body of `hello` subroutine.
130
131 When you are not interested in changes older than the version
132 v2.6.18, or changes older than 3 weeks, you can use revision
133 range specifiers similar to `git-rev-list`:
134
135 git blame v2.6.18.. -- foo
136 git blame --since=3.weeks -- foo
137
138 When revision range specifiers are used to limit the annotation,
139 lines that have not changed since the range boundary (either the
140 commit v2.6.18 or the most recent commit that is more than 3
141 weeks old in the above example) are blamed for that range
142 boundary commit.
143
144 A particularly useful way is to see if an added file have lines
145 created by copy-and-paste from existing files. Sometimes this
146 indicates that the developer was being sloppy and did not
147 refactor the code properly. You can first find the commit that
148 introduced the file with:
149
150 git log --diff-filter=A --pretty=short -- foo
151
152 and then annotate the change between the commit and its
153 parents, using `commit{caret}!` notation:
154
155 git blame -C -C -f $commit^! -- foo
156
157
158 SEE ALSO
159 --------
160 gitlink:git-annotate[1]
161
162 AUTHOR
163 ------
164 Written by Junio C Hamano <junkio@cox.net>
165
166 GIT
167 ---
168 Part of the gitlink:git[7] suite