1GIT-BLAME(1) Git Manual GIT-BLAME(1)
2
6 git-blame - Show what revision and author last modified each line of a
7 file
8
10 git blame [-c] [-b] [-l] [--root] [-t] [-f] [-n] [-s] [-e] [-p] [-w] [--incremental]
11 [-L <range>] [-S <revs-file>] [-M] [-C] [-C] [-C] [--since=<date>]
12 [--ignore-rev <rev>] [--ignore-revs-file <file>]
13 [--progress] [--abbrev=<n>] [<rev> | --contents <file> | --reverse <rev>..<rev>]
14 [--] <file>
15
17 Annotates each line in the given file with information from the
18 revision which last modified the line. Optionally, start annotating
19 from the given revision.
20 When specified one or more times, -L restricts annotation to the
22 requested lines.
23 The origin of lines is automatically followed across whole-file renames
25 (currently there is no option to turn the rename-following off). To
26 follow lines moved from one file to another, or to follow lines that
27 were copied and pasted from another file, etc., see the -C and -M
28 options.
29 The report does not tell you anything about lines which have been
31 deleted or replaced; you need to use a tool such as git diff or the
32 "pickaxe" interface briefly mentioned in the following paragraph.
33 Apart from supporting file annotation, Git also supports searching the
35 development history for when a code snippet occurred in a change. This
36 makes it possible to track when a code snippet was added to a file,
37 moved or copied between files, and eventually deleted or replaced. It
38 works by searching for a text string in the diff. A small example of
39 the pickaxe interface that searches for blame_usage:
40 $ git log --pretty=oneline -S'blame_usage'
42 5040f17eba15504bad66b14a645bddd9b015ebb7 blame -S <ancestry-file>
43 ea4c7f9bf69e781dd0cd88d2bccb2bf5cc15c9a7 git-blame: Make the output
44
46 -b
47 Show blank SHA-1 for boundary commits. This can also be controlled
48 via the blame.blankBoundary config option.
49 --root
51 Do not treat root commits as boundaries. This can also be
52 controlled via the blame.showRoot config option.
53 --show-stats
55 Include additional statistics at the end of blame output.
56 -L <start>,<end>, -L :<funcname>
58 Annotate only the line range given by <start>,<end>, or by the
59 function name regex <funcname>. May be specified multiple times.
60 Overlapping ranges are allowed.
61 <start> and <end> are optional. -L <start> or -L <start>, spans
63 from <start> to end of file. -L ,<end> spans from start of file to
64 <end>.
65 <start> and <end> can take one of these forms:
67 • number
69 If <start> or <end> is a number, it specifies an absolute line
71 number (lines count from 1).
72 • /regex/
74 This form will use the first line matching the given POSIX
76 regex. If <start> is a regex, it will search from the end of
77 the previous -L range, if any, otherwise from the start of
78 file. If <start> is ^/regex/, it will search from the start of
79 file. If <end> is a regex, it will search starting at the line
80 given by <start>.
81 • +offset or -offset
83 This is only valid for <end> and will specify a number of lines
85 before or after the line given by <start>.
86 If :<funcname> is given in place of <start> and <end>, it is a
88 regular expression that denotes the range from the first funcname
89 line that matches <funcname>, up to the next funcname line.
90 :<funcname> searches from the end of the previous -L range, if any,
91 otherwise from the start of file. ^:<funcname> searches from the
92 start of file. The function names are determined in the same way as
93 git diff works out patch hunk headers (see Defining a custom
94 hunk-header in gitattributes(5)).
95 -l
97 Show long rev (Default: off).
98 -t
100 Show raw timestamp (Default: off).
101 -S <revs-file>
103 Use revisions from revs-file instead of calling git-rev-list(1).
104 --reverse <rev>..<rev>
106 Walk history forward instead of backward. Instead of showing the
107 revision in which a line appeared, this shows the last revision in
108 which a line has existed. This requires a range of revision like
109 START..END where the path to blame exists in START. git blame
110 --reverse START is taken as git blame --reverse START..HEAD for
111 convenience.
112 --first-parent
114 Follow only the first parent commit upon seeing a merge commit.
115 This option can be used to determine when a line was introduced to
116 a particular integration branch, rather than when it was introduced
117 to the history overall.
118 -p, --porcelain
120 Show in a format designed for machine consumption.
121 --line-porcelain
123 Show the porcelain format, but output commit information for each
124 line, not just the first time a commit is referenced. Implies
125 --porcelain.
126 --incremental
128 Show the result incrementally in a format designed for machine
129 consumption.
130 --encoding=<encoding>
132 Specifies the encoding used to output author names and commit
133 summaries. Setting it to none makes blame output unconverted data.
134 For more information see the discussion about encoding in the git-
135 log(1) manual page.
136 --contents <file>
138 When <rev> is not specified, the command annotates the changes
139 starting backwards from the working tree copy. This flag makes the
140 command pretend as if the working tree copy has the contents of the
141 named file (specify - to make the command read from the standard
142 input).
143 --date <format>
145 Specifies the format used to output dates. If --date is not
146 provided, the value of the blame.date config variable is used. If
147 the blame.date config variable is also not set, the iso format is
148 used. For supported values, see the discussion of the --date option
149 at git-log(1).
150 --[no-]progress
152 Progress status is reported on the standard error stream by default
153 when it is attached to a terminal. This flag enables progress
154 reporting even if not attached to a terminal. Can’t use --progress
155 together with --porcelain or --incremental.
156 -M[<num>]
158 Detect moved or copied lines within a file. When a commit moves or
159 copies a block of lines (e.g. the original file has A and then B,
160 and the commit changes it to B and then A), the traditional blame
161 algorithm notices only half of the movement and typically blames
162 the lines that were moved up (i.e. B) to the parent and assigns
163 blame to the lines that were moved down (i.e. A) to the child
164 commit. With this option, both groups of lines are blamed on the
165 parent by running extra passes of inspection.
166 <num> is optional but it is the lower bound on the number of
168 alphanumeric characters that Git must detect as moving/copying
169 within a file for it to associate those lines with the parent
170 commit. The default value is 20.
171 -C[<num>]
173 In addition to -M, detect lines moved or copied from other files
174 that were modified in the same commit. This is useful when you
175 reorganize your program and move code around across files. When
176 this option is given twice, the command additionally looks for
177 copies from other files in the commit that creates the file. When
178 this option is given three times, the command additionally looks
179 for copies from other files in any commit.
180 <num> is optional but it is the lower bound on the number of
182 alphanumeric characters that Git must detect as moving/copying
183 between files for it to associate those lines with the parent
184 commit. And the default value is 40. If there are more than one -C
185 options given, the <num> argument of the last -C will take effect.
186 --ignore-rev <rev>
188 Ignore changes made by the revision when assigning blame, as if the
189 change never happened. Lines that were changed or added by an
190 ignored commit will be blamed on the previous commit that changed
191 that line or nearby lines. This option may be specified multiple
192 times to ignore more than one revision. If the
193 blame.markIgnoredLines config option is set, then lines that were
194 changed by an ignored commit and attributed to another commit will
195 be marked with a ? in the blame output. If the
196 blame.markUnblamableLines config option is set, then those lines
197 touched by an ignored commit that we could not attribute to another
198 revision are marked with a *.
199 --ignore-revs-file <file>
201 Ignore revisions listed in file, which must be in the same format
202 as an fsck.skipList. This option may be repeated, and these files
203 will be processed after any files specified with the
204 blame.ignoreRevsFile config option. An empty file name, "", will
205 clear the list of revs from previously processed files.
206 -h
208 Show help message.
209 -c
211 Use the same output mode as git-annotate(1) (Default: off).
212 --score-debug
214 Include debugging information related to the movement of lines
215 between files (see -C) and lines moved within a file (see -M). The
216 first number listed is the score. This is the number of
217 alphanumeric characters detected as having been moved between or
218 within files. This must be above a certain threshold for git blame
219 to consider those lines of code to have been moved.
220 -f, --show-name
222 Show the filename in the original commit. By default the filename
223 is shown if there is any line that came from a file with a
224 different name, due to rename detection.
225 -n, --show-number
227 Show the line number in the original commit (Default: off).
228 -s
230 Suppress the author name and timestamp from the output.
231 -e, --show-email
233 Show the author email instead of author name (Default: off). This
234 can also be controlled via the blame.showEmail config option.
235 -w
237 Ignore whitespace when comparing the parent’s version and the
238 child’s to find where the lines came from.
239 --abbrev=<n>
241 Instead of using the default 7+1 hexadecimal digits as the
242 abbreviated object name, use <m>+1 digits, where <m> is at least
243 <n> but ensures the commit object names are unique. Note that 1
244 column is used for a caret to mark the boundary commit.
245
247 In this format, each line is output after a header; the header at the
248 minimum has the first line which has:
249 • 40-byte SHA-1 of the commit the line is attributed to;
251 • the line number of the line in the original file;
253 • the line number of the line in the final file;
255 • on a line that starts a group of lines from a different commit than
257 the previous one, the number of lines in this group. On subsequent
258 lines this field is absent.
259 This header line is followed by the following information at least once
261 for each commit:
262 • the author name ("author"), email ("author-mail"), time
264 ("author-time"), and time zone ("author-tz"); similarly for
265 committer.
266 • the filename in the commit that the line is attributed to.
268 • the first line of the commit log message ("summary").
270 The contents of the actual line is output after the above header,
272 prefixed by a TAB. This is to allow adding more header elements later.
273 The porcelain format generally suppresses commit information that has
275 already been seen. For example, two lines that are blamed to the same
276 commit will both be shown, but the details for that commit will be
277 shown only once. This is more efficient, but may require more state be
278 kept by the reader. The --line-porcelain option can be used to output
279 full commit information for each line, allowing simpler (but less
280 efficient) usage like:
281 # count the number of lines attributed to each author
283 git blame --line-porcelain file |
284 sed -n 's/^author //p' |
285 sort | uniq -c | sort -rn
286
288 Unlike git blame and git annotate in older versions of git, the extent
289 of the annotation can be limited to both line ranges and revision
290 ranges. The -L option, which limits annotation to a range of lines, may
291 be specified multiple times.
292 When you are interested in finding the origin for lines 40-60 for file
294 foo, you can use the -L option like so (they mean the same thing — both
295 ask for 21 lines starting at line 40):
296 git blame -L 40,60 foo
298 git blame -L 40,+21 foo
299 Also you can use a regular expression to specify the line range:
301 git blame -L '/^sub hello {/,/^}$/' foo
303 which limits the annotation to the body of the hello subroutine.
305 When you are not interested in changes older than version v2.6.18, or
307 changes older than 3 weeks, you can use revision range specifiers
308 similar to git rev-list:
309 git blame v2.6.18.. -- foo
311 git blame --since=3.weeks -- foo
312 When revision range specifiers are used to limit the annotation, lines
314 that have not changed since the range boundary (either the commit
315 v2.6.18 or the most recent commit that is more than 3 weeks old in the
316 above example) are blamed for that range boundary commit.
317 A particularly useful way is to see if an added file has lines created
319 by copy-and-paste from existing files. Sometimes this indicates that
320 the developer was being sloppy and did not refactor the code properly.
321 You can first find the commit that introduced the file with:
322 git log --diff-filter=A --pretty=short -- foo
324 and then annotate the change between the commit and its parents, using
326 commit^! notation:
327 git blame -C -C -f $commit^! -- foo
329
331 When called with --incremental option, the command outputs the result
332 as it is built. The output generally will talk about lines touched by
333 more recent commits first (i.e. the lines will be annotated out of
334 order) and is meant to be used by interactive viewers.
335 The output format is similar to the Porcelain format, but it does not
337 contain the actual lines from the file that is being annotated.
338 1. Each blame entry always starts with a line of:
340 <40-byte hex sha1> <sourceline> <resultline> <num_lines>
342 Line numbers count from 1.
344 2. The first time that a commit shows up in the stream, it has various
346 other information about it printed out with a one-word tag at the
347 beginning of each line describing the extra commit information
348 (author, email, committer, dates, summary, etc.).
349 3. Unlike the Porcelain format, the filename information is always
351 given and terminates the entry:
352 "filename" <whitespace-quoted-filename-goes-here>
354 and thus it is really quite easy to parse for some line- and
356 word-oriented parser (which should be quite natural for most
357 scripting languages).
358 Note
360 For people who do parsing: to make it more robust, just ignore
361 any lines between the first and last one ("<sha1>" and
362 "filename" lines) where you do not recognize the tag words (or
363 care about that particular one) at the beginning of the
364 "extended information" lines. That way, if there is ever added
365 information (like the commit encoding or extended commit
366 commentary), a blame viewer will not care.
367
369 See gitmailmap(5).
370
372 git-annotate(1)
373
375 Part of the git(1) suite
376Git 2.31.1 2021-03-26 GIT-BLAME(1)