Document git blame --reverse.
[git/git.git] / Documentation / git-blame.txt
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1git-blame(1)
2============
3
4NAME
5----
26e8c5d3 6git-blame - Show what revision and author last modified each line of a file
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7
8SYNOPSIS
9--------
acca687f 10[verse]
b1889c36 11'git blame' [-c] [-b] [-l] [--root] [-t] [-f] [-n] [-s] [-p] [-w] [--incremental] [-L n,m]
635f4a30 12 [-S <revs-file>] [-M] [-C] [-C] [--since=<date>]
b452cc16 13 [<rev> | --contents <file> | --reverse <rev>] [--] <file>
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14
15DESCRIPTION
16-----------
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17
18Annotates each line in the given file with information from the revision which
19last modified the line. Optionally, start annotating from the given revision.
20
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21Also it can limit the range of lines annotated.
22
26e8c5d3 23This report doesn't tell you anything about lines which have been deleted or
ba020ef5 24replaced; you need to use a tool such as 'git-diff' or the "pickaxe"
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25interface briefly mentioned in the following paragraph.
26
27Apart from supporting file annotation, git also supports searching the
23bfbb81 28development history for when a code snippet occurred in a change. This makes it
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29possible to track when a code snippet was added to a file, moved or copied
30between files, and eventually deleted or replaced. It works by searching for
31a text string in the diff. A small example:
32
33-----------------------------------------------------------------------------
34$ git log --pretty=oneline -S'blame_usage'
355040f17eba15504bad66b14a645bddd9b015ebb7 blame -S <ancestry-file>
36ea4c7f9bf69e781dd0cd88d2bccb2bf5cc15c9a7 git-blame: Make the output
37-----------------------------------------------------------------------------
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38
39OPTIONS
40-------
635f4a30 41include::blame-options.txt[]
b19ee24b 42
635f4a30 43-c::
5162e697 44 Use the same output mode as linkgit:git-annotate[1] (Default: off).
8f2b72a9 45
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46--score-debug::
47 Include debugging information related to the movement of
48 lines between files (see `-C`) and lines moved within a
49 file (see `-M`). The first number listed is the score.
50 This is the number of alphanumeric characters detected
51 to be moved between or within files. This must be above
ba020ef5 52 a certain threshold for 'git-blame' to consider those lines
635f4a30 53 of code to have been moved.
8f2b72a9 54
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55-f::
56--show-name::
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57 Show filename in the original commit. By default
58 filename is shown if there is any line that came from a
59 file with different name, due to rename detection.
60
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61-n::
62--show-number::
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63 Show line number in the original commit (Default: off).
64
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65-s::
66 Suppress author name and timestamp from the output.
67
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68-w::
69 Ignore whitespace when comparing parent's version and
70 child's to find where the lines came from.
71
72
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73THE PORCELAIN FORMAT
74--------------------
75
76In this format, each line is output after a header; the
23bfbb81 77header at the minimum has the first line which has:
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78
79- 40-byte SHA-1 of the commit the line is attributed to;
80- the line number of the line in the original file;
81- the line number of the line in the final file;
82- on a line that starts a group of line from a different
83 commit than the previous one, the number of lines in this
84 group. On subsequent lines this field is absent.
85
86This header line is followed by the following information
87at least once for each commit:
88
89- author name ("author"), email ("author-mail"), time
90 ("author-time"), and timezone ("author-tz"); similarly
91 for committer.
92- filename in the commit the line is attributed to.
93- the first line of the commit log message ("summary").
94
95The contents of the actual line is output after the above
96header, prefixed by a TAB. This is to allow adding more
97header elements later.
98
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100SPECIFYING RANGES
101-----------------
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ba020ef5 103Unlike 'git-blame' and 'git-annotate' in older git, the extent
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104of annotation can be limited to both line ranges and revision
105ranges. When you are interested in finding the origin for
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106ll. 40-60 for file `foo`, you can use `-L` option like these
107(they mean the same thing -- both ask for 21 lines starting at
108line 40):
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109
110 git blame -L 40,60 foo
42f62db9 111 git blame -L 40,+21 foo
acca687f 112
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113Also you can use regular expression to specify the line range.
114
115 git blame -L '/^sub hello {/,/^}$/' foo
116
117would limit the annotation to the body of `hello` subroutine.
118
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119When you are not interested in changes older than the version
120v2.6.18, or changes older than 3 weeks, you can use revision
ba020ef5 121range specifiers similar to 'git-rev-list':
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122
123 git blame v2.6.18.. -- foo
124 git blame --since=3.weeks -- foo
125
126When revision range specifiers are used to limit the annotation,
127lines that have not changed since the range boundary (either the
128commit v2.6.18 or the most recent commit that is more than 3
129weeks old in the above example) are blamed for that range
130boundary commit.
131
132A particularly useful way is to see if an added file have lines
133created by copy-and-paste from existing files. Sometimes this
134indicates that the developer was being sloppy and did not
135refactor the code properly. You can first find the commit that
136introduced the file with:
137
138 git log --diff-filter=A --pretty=short -- foo
139
140and then annotate the change between the commit and its
141parents, using `commit{caret}!` notation:
142
143 git blame -C -C -f $commit^! -- foo
144
145
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146INCREMENTAL OUTPUT
147------------------
148
149When called with `--incremental` option, the command outputs the
150result as it is built. The output generally will talk about
151lines touched by more recent commits first (i.e. the lines will
152be annotated out of order) and is meant to be used by
153interactive viewers.
154
155The output format is similar to the Porcelain format, but it
156does not contain the actual lines from the file that is being
157annotated.
158
159. Each blame entry always starts with a line of:
160
161 <40-byte hex sha1> <sourceline> <resultline> <num_lines>
162+
163Line numbers count from 1.
164
165. The first time that commit shows up in the stream, it has various
166 other information about it printed out with a one-word tag at the
167 beginning of each line about that "extended commit info" (author,
168 email, committer, dates, summary etc).
169
170. Unlike Porcelain format, the filename information is always
171 given and terminates the entry:
172
173 "filename" <whitespace-quoted-filename-goes-here>
174+
175and thus it's really quite easy to parse for some line- and word-oriented
176parser (which should be quite natural for most scripting languages).
177+
178[NOTE]
179For people who do parsing: to make it more robust, just ignore any
180lines in between the first and last one ("<sha1>" and "filename" lines)
181where you don't recognize the tag-words (or care about that particular
182one) at the beginning of the "extended information" lines. That way, if
183there is ever added information (like the commit encoding or extended
184commit commentary), a blame viewer won't ever care.
185
186
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187SEE ALSO
188--------
5162e697 189linkgit:git-annotate[1]
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190
191AUTHOR
192------
59eb68aa 193Written by Junio C Hamano <gitster@pobox.com>
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194
195GIT
196---
9e1f0a85 197Part of the linkgit:git[1] suite