blame: honor the diff heuristic options and config
[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]
13b8f68c 11'git blame' [-c] [-b] [-l] [--root] [-t] [-f] [-n] [-s] [-e] [-p] [-w] [--incremental]
5bd9b79a 12 [-L <range>] [-S <revs-file>] [-M] [-C] [-C] [-C] [--since=<date>]
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13 [--progress] [--abbrev=<n>] [<rev> | --contents <file> | --reverse <rev>]
14 [--] <file>
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15
16DESCRIPTION
17-----------
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18
19Annotates each line in the given file with information from the revision which
20last modified the line. Optionally, start annotating from the given revision.
21
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22When specified one or more times, `-L` restricts annotation to the requested
23lines.
acca687f 24
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25The origin of lines is automatically followed across whole-file
26renames (currently there is no option to turn the rename-following
27off). To follow lines moved from one file to another, or to follow
28lines that were copied and pasted from another file, etc., see the
29`-C` and `-M` options.
30
b89510f0 31The report does not tell you anything about lines which have been deleted or
0b444cdb 32replaced; you need to use a tool such as 'git diff' or the "pickaxe"
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33interface briefly mentioned in the following paragraph.
34
2de9b711 35Apart from supporting file annotation, Git also supports searching the
23bfbb81 36development history for when a code snippet occurred in a change. This makes it
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37possible to track when a code snippet was added to a file, moved or copied
38between files, and eventually deleted or replaced. It works by searching for
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39a text string in the diff. A small example of the pickaxe interface
40that searches for `blame_usage`:
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41
42-----------------------------------------------------------------------------
43$ git log --pretty=oneline -S'blame_usage'
445040f17eba15504bad66b14a645bddd9b015ebb7 blame -S <ancestry-file>
45ea4c7f9bf69e781dd0cd88d2bccb2bf5cc15c9a7 git-blame: Make the output
46-----------------------------------------------------------------------------
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47
48OPTIONS
49-------
635f4a30 50include::blame-options.txt[]
b19ee24b 51
635f4a30 52-c::
5162e697 53 Use the same output mode as linkgit:git-annotate[1] (Default: off).
8f2b72a9 54
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55--score-debug::
56 Include debugging information related to the movement of
57 lines between files (see `-C`) and lines moved within a
58 file (see `-M`). The first number listed is the score.
59 This is the number of alphanumeric characters detected
b89510f0 60 as having been moved between or within files. This must be above
0b444cdb 61 a certain threshold for 'git blame' to consider those lines
635f4a30 62 of code to have been moved.
8f2b72a9 63
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64-f::
65--show-name::
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66 Show the filename in the original commit. By default
67 the filename is shown if there is any line that came from a
68 file with a different name, due to rename detection.
b24642b2 69
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70-n::
71--show-number::
b89510f0 72 Show the line number in the original commit (Default: off).
b24642b2 73
093dc5be 74-s::
b89510f0 75 Suppress the author name and timestamp from the output.
093dc5be 76
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77-e::
78--show-email::
79 Show the author email instead of author name (Default: off).
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80 This can also be controlled via the `blame.showEmail` config
81 option.
1b8cdce9 82
b82871b3 83-w::
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84 Ignore whitespace when comparing the parent's version and
85 the child's to find where the lines came from.
b82871b3 86
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87--abbrev=<n>::
88 Instead of using the default 7+1 hexadecimal digits as the
89 abbreviated object name, use <n>+1 digits. Note that 1 column
90 is used for a caret to mark the boundary commit.
91
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92include::diff-heuristic-options.txt[]
93
b82871b3 94
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95THE PORCELAIN FORMAT
96--------------------
97
98In this format, each line is output after a header; the
23bfbb81 99header at the minimum has the first line which has:
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100
101- 40-byte SHA-1 of the commit the line is attributed to;
102- the line number of the line in the original file;
103- the line number of the line in the final file;
b89510f0 104- on a line that starts a group of lines from a different
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105 commit than the previous one, the number of lines in this
106 group. On subsequent lines this field is absent.
107
108This header line is followed by the following information
109at least once for each commit:
110
b89510f0 111- the author name ("author"), email ("author-mail"), time
0ffa154b 112 ("author-time"), and time zone ("author-tz"); similarly
b24642b2 113 for committer.
b89510f0 114- the filename in the commit that the line is attributed to.
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115- the first line of the commit log message ("summary").
116
117The contents of the actual line is output after the above
118header, prefixed by a TAB. This is to allow adding more
119header elements later.
120
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121The porcelain format generally suppresses commit information that has
122already been seen. For example, two lines that are blamed to the same
123commit will both be shown, but the details for that commit will be shown
124only once. This is more efficient, but may require more state be kept by
125the reader. The `--line-porcelain` option can be used to output full
126commit information for each line, allowing simpler (but less efficient)
127usage like:
128
129 # count the number of lines attributed to each author
130 git blame --line-porcelain file |
131 sed -n 's/^author //p' |
132 sort | uniq -c | sort -rn
133
acca687f 134
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135SPECIFYING RANGES
136-----------------
acca687f 137
0b444cdb 138Unlike 'git blame' and 'git annotate' in older versions of git, the extent
b89510f0 139of the annotation can be limited to both line ranges and revision
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140ranges. The `-L` option, which limits annotation to a range of lines, may be
141specified multiple times.
142
143When you are interested in finding the origin for
b89510f0 144lines 40-60 for file `foo`, you can use the `-L` option like so
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145(they mean the same thing -- both ask for 21 lines starting at
146line 40):
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147
148 git blame -L 40,60 foo
42f62db9 149 git blame -L 40,+21 foo
acca687f 150
b89510f0 151Also you can use a regular expression to specify the line range:
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152
153 git blame -L '/^sub hello {/,/^}$/' foo
154
b89510f0 155which limits the annotation to the body of the `hello` subroutine.
18d5453e 156
b89510f0 157When you are not interested in changes older than version
acca687f 158v2.6.18, or changes older than 3 weeks, you can use revision
0b444cdb 159range specifiers similar to 'git rev-list':
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160
161 git blame v2.6.18.. -- foo
162 git blame --since=3.weeks -- foo
163
164When revision range specifiers are used to limit the annotation,
165lines that have not changed since the range boundary (either the
166commit v2.6.18 or the most recent commit that is more than 3
167weeks old in the above example) are blamed for that range
168boundary commit.
169
b89510f0 170A particularly useful way is to see if an added file has lines
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171created by copy-and-paste from existing files. Sometimes this
172indicates that the developer was being sloppy and did not
173refactor the code properly. You can first find the commit that
174introduced the file with:
175
176 git log --diff-filter=A --pretty=short -- foo
177
178and then annotate the change between the commit and its
6cf378f0 179parents, using `commit^!` notation:
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180
181 git blame -C -C -f $commit^! -- foo
182
183
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184INCREMENTAL OUTPUT
185------------------
186
187When called with `--incremental` option, the command outputs the
188result as it is built. The output generally will talk about
189lines touched by more recent commits first (i.e. the lines will
190be annotated out of order) and is meant to be used by
191interactive viewers.
192
193The output format is similar to the Porcelain format, but it
194does not contain the actual lines from the file that is being
195annotated.
196
197. Each blame entry always starts with a line of:
198
199 <40-byte hex sha1> <sourceline> <resultline> <num_lines>
200+
201Line numbers count from 1.
202
b89510f0 203. The first time that a commit shows up in the stream, it has various
57e7a0a4 204 other information about it printed out with a one-word tag at the
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205 beginning of each line describing the extra commit information (author,
206 email, committer, dates, summary, etc.).
57e7a0a4 207
b89510f0 208. Unlike the Porcelain format, the filename information is always
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209 given and terminates the entry:
210
211 "filename" <whitespace-quoted-filename-goes-here>
212+
b89510f0 213and thus it is really quite easy to parse for some line- and word-oriented
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214parser (which should be quite natural for most scripting languages).
215+
216[NOTE]
217For people who do parsing: to make it more robust, just ignore any
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218lines between the first and last one ("<sha1>" and "filename" lines)
219where you do not recognize the tag words (or care about that particular
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220one) at the beginning of the "extended information" lines. That way, if
221there is ever added information (like the commit encoding or extended
b89510f0 222commit commentary), a blame viewer will not care.
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223
224
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225MAPPING AUTHORS
226---------------
227
228include::mailmap.txt[]
229
230
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231SEE ALSO
232--------
5162e697 233linkgit:git-annotate[1]
8f2b72a9 234
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235GIT
236---
9e1f0a85 237Part of the linkgit:git[1] suite