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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 [--ignore-rev <rev>] [--ignore-revs-file <file>]
14 [--color-lines] [--color-by-age] [--progress] [--abbrev=<n>]
15 [<rev> | --contents <file> | --reverse <rev>..<rev>] [--] <file>
16
17 DESCRIPTION
18 -----------
19
20 Annotates each line in the given file with information from the revision which
21 last modified the line. Optionally, start annotating from the given revision.
22
23 When specified one or more times, `-L` restricts annotation to the requested
24 lines.
25
26 The origin of lines is automatically followed across whole-file
27 renames (currently there is no option to turn the rename-following
28 off). To follow lines moved from one file to another, or to follow
29 lines that were copied and pasted from another file, etc., see the
30 `-C` and `-M` options.
31
32 The report does not tell you anything about lines which have been deleted or
33 replaced; you need to use a tool such as 'git diff' or the "pickaxe"
34 interface briefly mentioned in the following paragraph.
35
36 Apart from supporting file annotation, Git also supports searching the
37 development history for when a code snippet occurred in a change. This makes it
38 possible to track when a code snippet was added to a file, moved or copied
39 between files, and eventually deleted or replaced. It works by searching for
40 a text string in the diff. A small example of the pickaxe interface
41 that searches for `blame_usage`:
42
43 -----------------------------------------------------------------------------
44 $ git log --pretty=oneline -S'blame_usage'
45 5040f17eba15504bad66b14a645bddd9b015ebb7 blame -S <ancestry-file>
46 ea4c7f9bf69e781dd0cd88d2bccb2bf5cc15c9a7 git-blame: Make the output
47 -----------------------------------------------------------------------------
48
49 OPTIONS
50 -------
51 include::blame-options.txt[]
52
53 -c::
54 Use the same output mode as linkgit:git-annotate[1] (Default: off).
55
56 --score-debug::
57 Include debugging information related to the movement of
58 lines between files (see `-C`) and lines moved within a
59 file (see `-M`). The first number listed is the score.
60 This is the number of alphanumeric characters detected
61 as having been moved between or within files. This must be above
62 a certain threshold for 'git blame' to consider those lines
63 of code to have been moved.
64
65 -f::
66 --show-name::
67 Show the filename in the original commit. By default
68 the filename is shown if there is any line that came from a
69 file with a different name, due to rename detection.
70
71 -n::
72 --show-number::
73 Show the line number in the original commit (Default: off).
74
75 -s::
76 Suppress the author name and timestamp from the output.
77
78 -e::
79 --show-email::
80 Show the author email instead of author name (Default: off).
81 This can also be controlled via the `blame.showEmail` config
82 option.
83
84 -w::
85 Ignore whitespace when comparing the parent's version and
86 the child's to find where the lines came from.
87
88 --abbrev=<n>::
89 Instead of using the default 7+1 hexadecimal digits as the
90 abbreviated object name, use <m>+1 digits, where <m> is at
91 least <n> but ensures the commit object names are unique.
92 Note that 1 column
93 is used for a caret to mark the boundary commit.
94
95
96 THE DEFAULT FORMAT
97 ------------------
98
99 When neither `--porcelain` nor `--incremental` option is specified,
100 `git blame` will output annotation for each line with:
101
102 - abbreviated object name for the commit the line came from;
103 - author ident (by default author name and date, unless `-s` or `-e`
104 is specified); and
105 - line number
106
107 before the line contents.
108
109 THE PORCELAIN FORMAT
110 --------------------
111
112 In this format, each line is output after a header; the
113 header at the minimum has the first line which has:
114
115 - 40-byte SHA-1 of the commit the line is attributed to;
116 - the line number of the line in the original file;
117 - the line number of the line in the final file;
118 - on a line that starts a group of lines from a different
119 commit than the previous one, the number of lines in this
120 group. On subsequent lines this field is absent.
121
122 This header line is followed by the following information
123 at least once for each commit:
124
125 - the author name ("author"), email ("author-mail"), time
126 ("author-time"), and time zone ("author-tz"); similarly
127 for committer.
128 - the filename in the commit that the line is attributed to.
129 - the first line of the commit log message ("summary").
130
131 The contents of the actual line is output after the above
132 header, prefixed by a TAB. This is to allow adding more
133 header elements later.
134
135 The porcelain format generally suppresses commit information that has
136 already been seen. For example, two lines that are blamed to the same
137 commit will both be shown, but the details for that commit will be shown
138 only once. This is more efficient, but may require more state be kept by
139 the reader. The `--line-porcelain` option can be used to output full
140 commit information for each line, allowing simpler (but less efficient)
141 usage like:
142
143 # count the number of lines attributed to each author
144 git blame --line-porcelain file |
145 sed -n 's/^author //p' |
146 sort | uniq -c | sort -rn
147
148
149 SPECIFYING RANGES
150 -----------------
151
152 Unlike 'git blame' and 'git annotate' in older versions of git, the extent
153 of the annotation can be limited to both line ranges and revision
154 ranges. The `-L` option, which limits annotation to a range of lines, may be
155 specified multiple times.
156
157 When you are interested in finding the origin for
158 lines 40-60 for file `foo`, you can use the `-L` option like so
159 (they mean the same thing -- both ask for 21 lines starting at
160 line 40):
161
162 git blame -L 40,60 foo
163 git blame -L 40,+21 foo
164
165 Also you can use a regular expression to specify the line range:
166
167 git blame -L '/^sub hello {/,/^}$/' foo
168
169 which limits the annotation to the body of the `hello` subroutine.
170
171 When you are not interested in changes older than version
172 v2.6.18, or changes older than 3 weeks, you can use revision
173 range specifiers similar to 'git rev-list':
174
175 git blame v2.6.18.. -- foo
176 git blame --since=3.weeks -- foo
177
178 When revision range specifiers are used to limit the annotation,
179 lines that have not changed since the range boundary (either the
180 commit v2.6.18 or the most recent commit that is more than 3
181 weeks old in the above example) are blamed for that range
182 boundary commit.
183
184 A particularly useful way is to see if an added file has lines
185 created by copy-and-paste from existing files. Sometimes this
186 indicates that the developer was being sloppy and did not
187 refactor the code properly. You can first find the commit that
188 introduced the file with:
189
190 git log --diff-filter=A --pretty=short -- foo
191
192 and then annotate the change between the commit and its
193 parents, using `commit^!` notation:
194
195 git blame -C -C -f $commit^! -- foo
196
197
198 INCREMENTAL OUTPUT
199 ------------------
200
201 When called with `--incremental` option, the command outputs the
202 result as it is built. The output generally will talk about
203 lines touched by more recent commits first (i.e. the lines will
204 be annotated out of order) and is meant to be used by
205 interactive viewers.
206
207 The output format is similar to the Porcelain format, but it
208 does not contain the actual lines from the file that is being
209 annotated.
210
211 . Each blame entry always starts with a line of:
212
213 <40-byte hex sha1> <sourceline> <resultline> <num_lines>
214 +
215 Line numbers count from 1.
216
217 . The first time that a commit shows up in the stream, it has various
218 other information about it printed out with a one-word tag at the
219 beginning of each line describing the extra commit information (author,
220 email, committer, dates, summary, etc.).
221
222 . Unlike the Porcelain format, the filename information is always
223 given and terminates the entry:
224
225 "filename" <whitespace-quoted-filename-goes-here>
226 +
227 and thus it is really quite easy to parse for some line- and word-oriented
228 parser (which should be quite natural for most scripting languages).
229 +
230 [NOTE]
231 For people who do parsing: to make it more robust, just ignore any
232 lines between the first and last one ("<sha1>" and "filename" lines)
233 where you do not recognize the tag words (or care about that particular
234 one) at the beginning of the "extended information" lines. That way, if
235 there is ever added information (like the commit encoding or extended
236 commit commentary), a blame viewer will not care.
237
238
239 MAPPING AUTHORS
240 ---------------
241
242 See linkgit:gitmailmap[5].
243
244 CONFIGURATION
245 -------------
246
247 include::includes/cmd-config-section-all.txt[]
248
249 include::config/blame.txt[]
250
251 SEE ALSO
252 --------
253 linkgit:git-annotate[1]
254
255 GIT
256 ---
257 Part of the linkgit:git[1] suite