blame: honor the diff heuristic options and config
[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] [-b] [-l] [--root] [-t] [-f] [-n] [-s] [-e] [-p] [-w] [--incremental]
12 [-L <range>] [-S <revs-file>] [-M] [-C] [-C] [-C] [--since=<date>]
13 [--progress] [--abbrev=<n>] [<rev> | --contents <file> | --reverse <rev>]
14 [--] <file>
15
16 DESCRIPTION
17 -----------
18
19 Annotates each line in the given file with information from the revision which
20 last modified the line. Optionally, start annotating from the given revision.
21
22 When specified one or more times, `-L` restricts annotation to the requested
23 lines.
24
25 The origin of lines is automatically followed across whole-file
26 renames (currently there is no option to turn the rename-following
27 off). To follow lines moved from one file to another, or to follow
28 lines that were copied and pasted from another file, etc., see the
29 `-C` and `-M` options.
30
31 The report does not tell you anything about lines which have been deleted or
32 replaced; you need to use a tool such as 'git diff' or the "pickaxe"
33 interface briefly mentioned in the following paragraph.
34
35 Apart from supporting file annotation, Git also supports searching the
36 development history for when a code snippet occurred in a change. This makes it
37 possible to track when a code snippet was added to a file, moved or copied
38 between files, and eventually deleted or replaced. It works by searching for
39 a text string in the diff. A small example of the pickaxe interface
40 that searches for `blame_usage`:
41
42 -----------------------------------------------------------------------------
43 $ git log --pretty=oneline -S'blame_usage'
44 5040f17eba15504bad66b14a645bddd9b015ebb7 blame -S <ancestry-file>
45 ea4c7f9bf69e781dd0cd88d2bccb2bf5cc15c9a7 git-blame: Make the output
46 -----------------------------------------------------------------------------
47
48 OPTIONS
49 -------
50 include::blame-options.txt[]
51
52 -c::
53 Use the same output mode as linkgit:git-annotate[1] (Default: off).
54
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
60 as having been moved between or within files. This must be above
61 a certain threshold for 'git blame' to consider those lines
62 of code to have been moved.
63
64 -f::
65 --show-name::
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.
69
70 -n::
71 --show-number::
72 Show the line number in the original commit (Default: off).
73
74 -s::
75 Suppress the author name and timestamp from the output.
76
77 -e::
78 --show-email::
79 Show the author email instead of author name (Default: off).
80 This can also be controlled via the `blame.showEmail` config
81 option.
82
83 -w::
84 Ignore whitespace when comparing the parent's version and
85 the child's to find where the lines came from.
86
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
92 include::diff-heuristic-options.txt[]
93
94
95 THE PORCELAIN FORMAT
96 --------------------
97
98 In this format, each line is output after a header; the
99 header at the minimum has the first line which has:
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;
104 - on a line that starts a group of lines from a different
105 commit than the previous one, the number of lines in this
106 group. On subsequent lines this field is absent.
107
108 This header line is followed by the following information
109 at least once for each commit:
110
111 - the author name ("author"), email ("author-mail"), time
112 ("author-time"), and time zone ("author-tz"); similarly
113 for committer.
114 - the filename in the commit that the line is attributed to.
115 - the first line of the commit log message ("summary").
116
117 The contents of the actual line is output after the above
118 header, prefixed by a TAB. This is to allow adding more
119 header elements later.
120
121 The porcelain format generally suppresses commit information that has
122 already been seen. For example, two lines that are blamed to the same
123 commit will both be shown, but the details for that commit will be shown
124 only once. This is more efficient, but may require more state be kept by
125 the reader. The `--line-porcelain` option can be used to output full
126 commit information for each line, allowing simpler (but less efficient)
127 usage 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
134
135 SPECIFYING RANGES
136 -----------------
137
138 Unlike 'git blame' and 'git annotate' in older versions of git, the extent
139 of the annotation can be limited to both line ranges and revision
140 ranges. The `-L` option, which limits annotation to a range of lines, may be
141 specified multiple times.
142
143 When you are interested in finding the origin for
144 lines 40-60 for file `foo`, you can use the `-L` option like so
145 (they mean the same thing -- both ask for 21 lines starting at
146 line 40):
147
148 git blame -L 40,60 foo
149 git blame -L 40,+21 foo
150
151 Also you can use a regular expression to specify the line range:
152
153 git blame -L '/^sub hello {/,/^}$/' foo
154
155 which limits the annotation to the body of the `hello` subroutine.
156
157 When you are not interested in changes older than version
158 v2.6.18, or changes older than 3 weeks, you can use revision
159 range specifiers similar to 'git rev-list':
160
161 git blame v2.6.18.. -- foo
162 git blame --since=3.weeks -- foo
163
164 When revision range specifiers are used to limit the annotation,
165 lines that have not changed since the range boundary (either the
166 commit v2.6.18 or the most recent commit that is more than 3
167 weeks old in the above example) are blamed for that range
168 boundary commit.
169
170 A particularly useful way is to see if an added file has lines
171 created by copy-and-paste from existing files. Sometimes this
172 indicates that the developer was being sloppy and did not
173 refactor the code properly. You can first find the commit that
174 introduced the file with:
175
176 git log --diff-filter=A --pretty=short -- foo
177
178 and then annotate the change between the commit and its
179 parents, using `commit^!` notation:
180
181 git blame -C -C -f $commit^! -- foo
182
183
184 INCREMENTAL OUTPUT
185 ------------------
186
187 When called with `--incremental` option, the command outputs the
188 result as it is built. The output generally will talk about
189 lines touched by more recent commits first (i.e. the lines will
190 be annotated out of order) and is meant to be used by
191 interactive viewers.
192
193 The output format is similar to the Porcelain format, but it
194 does not contain the actual lines from the file that is being
195 annotated.
196
197 . Each blame entry always starts with a line of:
198
199 <40-byte hex sha1> <sourceline> <resultline> <num_lines>
200 +
201 Line numbers count from 1.
202
203 . The first time that a commit shows up in the stream, it has various
204 other information about it printed out with a one-word tag at the
205 beginning of each line describing the extra commit information (author,
206 email, committer, dates, summary, etc.).
207
208 . Unlike the Porcelain format, the filename information is always
209 given and terminates the entry:
210
211 "filename" <whitespace-quoted-filename-goes-here>
212 +
213 and thus it is really quite easy to parse for some line- and word-oriented
214 parser (which should be quite natural for most scripting languages).
215 +
216 [NOTE]
217 For people who do parsing: to make it more robust, just ignore any
218 lines between the first and last one ("<sha1>" and "filename" lines)
219 where you do not recognize the tag words (or care about that particular
220 one) at the beginning of the "extended information" lines. That way, if
221 there is ever added information (like the commit encoding or extended
222 commit commentary), a blame viewer will not care.
223
224
225 MAPPING AUTHORS
226 ---------------
227
228 include::mailmap.txt[]
229
230
231 SEE ALSO
232 --------
233 linkgit:git-annotate[1]
234
235 GIT
236 ---
237 Part of the linkgit:git[1] suite