GIT-BLAME(1) Git Manual GIT-BLAME(1)

NAME

git-blame - Show what revision and author last modified each line of
a file

SYNOPSIS

git blame [-c] [-b] [-l] [--root] [-t] [-f] [-n] [-s] [-e] [-p] [-w] [--incremental]
[-L <range>] [-S <revs-file>] [-M] [-C] [-C] [-C] [--since=<date>]
[--ignore-rev <rev>] [--ignore-revs-file <file>]
[--color-lines] [--color-by-age] [--progress] [--abbrev=<n>]
[ --contents <file> ] [<rev> | --reverse <rev>..<rev>] [--] <file>

DESCRIPTION

Annotates each line in the given file with information from the
revision which last modified the line. Optionally, start annotating
from the given revision.

When specified one or more times, -L restricts annotation to the
requested lines.

The origin of lines is automatically followed across whole-file
renames (currently there is no option to turn the rename-following
off). To follow lines moved from one file to another, or to follow
lines that were copied and pasted from another file, etc., see the -C
and -M options.

The report does not tell you anything about lines which have been
deleted or replaced; you need to use a tool such as git diff or the
"pickaxe" interface briefly mentioned in the following paragraph.

Apart from supporting file annotation, Git also supports searching
the development history for when a code snippet occurred in a change.
This makes it possible to track when a code snippet was added to a
file, moved or copied between files, and eventually deleted or
replaced. It works by searching for a text string in the diff. A
small example of the pickaxe interface that searches for blame_usage:

$ git log --pretty=oneline -S'blame_usage'
5040f17eba15504bad66b14a645bddd9b015ebb7 blame -S <ancestry-file>
ea4c7f9bf69e781dd0cd88d2bccb2bf5cc15c9a7 git-blame: Make the output

OPTIONS

-b
Show blank SHA-1 for boundary commits. This can also be
controlled via the blame.blankBoundary config option.

--root
Do not treat root commits as boundaries. This can also be
controlled via the blame.showRoot config option.

--show-stats
Include additional statistics at the end of blame output.

-L <start>,<end>, -L :<funcname>
Annotate only the line range given by <start>,<end>, or by the
function name regex <funcname>. May be specified multiple times.
Overlapping ranges are allowed.

<start> and <end> are optional. -L <start> or -L <start>, spans
from <start> to end of file. -L ,<end> spans from start of file
to <end>.

<start> and <end> can take one of these forms:

+o number

If <start> or <end> is a number, it specifies an absolute
line number (lines count from 1).

+o /regex/

This form will use the first line matching the given POSIX
regex. If <start> is a regex, it will search from the end of
the previous -L range, if any, otherwise from the start of
file. If <start> is ^/regex/, it will search from the start
of file. If <end> is a regex, it will search starting at the
line given by <start>.

+o +offset or -offset

This is only valid for <end> and will specify a number of
lines before or after the line given by <start>.

If :<funcname> is given in place of <start> and <end>, it is a
regular expression that denotes the range from the first funcname
line that matches <funcname>, up to the next funcname line.
:<funcname> searches from the end of the previous -L range, if
any, otherwise from the start of file. ^:<funcname> searches
from the start of file. The function names are determined in the
same way as git diff works out patch hunk headers (see Defining a
custom hunk-header in gitattributes(5)).

-l
Show long rev (Default: off).

-t
Show raw timestamp (Default: off).

-S <revs-file>
Use revisions from revs-file instead of calling git-rev-list(1).

--reverse <rev>..<rev>
Walk history forward instead of backward. Instead of showing the
revision in which a line appeared, this shows the last revision
in which a line has existed. This requires a range of revision
like START..END where the path to blame exists in START. git
blame --reverse START is taken as git blame --reverse START..HEAD
for convenience.

--first-parent
Follow only the first parent commit upon seeing a merge commit.
This option can be used to determine when a line was introduced
to a particular integration branch, rather than when it was
introduced to the history overall.

-p, --porcelain
Show in a format designed for machine consumption.

--line-porcelain
Show the porcelain format, but output commit information for each
line, not just the first time a commit is referenced. Implies
--porcelain.

--incremental
Show the result incrementally in a format designed for machine
consumption.

--encoding=<encoding>
Specifies the encoding used to output author names and commit
summaries. Setting it to none makes blame output unconverted
data. For more information see the discussion about encoding in
the git-log(1) manual page.

--contents <file>
Annotate using the contents from the named file, starting from
<rev> if it is specified, and HEAD otherwise. You may specify -
to make the command read from the standard input for the file
contents.

--date <format>
Specifies the format used to output dates. If --date is not
provided, the value of the blame.date config variable is used. If
the blame.date config variable is also not set, the iso format is
used. For supported values, see the discussion of the --date
option at git-log(1).

--[no-]progress
Progress status is reported on the standard error stream by
default when it is attached to a terminal. This flag enables
progress reporting even if not attached to a terminal. Can't use
--progress together with --porcelain or --incremental.

-M[<num>]
Detect moved or copied lines within a file. When a commit moves
or copies a block of lines (e.g. the original file has A and then
B, and the commit changes it to B and then A), the traditional
blame algorithm notices only half of the movement and typically
blames the lines that were moved up (i.e. B) to the parent and
assigns blame to the lines that were moved down (i.e. A) to the
child commit. With this option, both groups of lines are blamed
on the parent by running extra passes of inspection.

<num> is optional but it is the lower bound on the number of
alphanumeric characters that Git must detect as moving/copying
within a file for it to associate those lines with the parent
commit. The default value is 20.

-C[<num>]
In addition to -M, detect lines moved or copied from other files
that were modified in the same commit. This is useful when you
reorganize your program and move code around across files. When
this option is given twice, the command additionally looks for
copies from other files in the commit that creates the file. When
this option is given three times, the command additionally looks
for copies from other files in any commit.

<num> is optional but it is the lower bound on the number of
alphanumeric characters that Git must detect as moving/copying
between files for it to associate those lines with the parent
commit. And the default value is 40. If there are more than one
-C options given, the <num> argument of the last -C will take
effect.

--ignore-rev <rev>
Ignore changes made by the revision when assigning blame, as if
the change never happened. Lines that were changed or added by an
ignored commit will be blamed on the previous commit that changed
that line or nearby lines. This option may be specified multiple
times to ignore more than one revision. If the
blame.markIgnoredLines config option is set, then lines that were
changed by an ignored commit and attributed to another commit
will be marked with a ? in the blame output. If the
blame.markUnblamableLines config option is set, then those lines
touched by an ignored commit that we could not attribute to
another revision are marked with a *.

--ignore-revs-file <file>
Ignore revisions listed in file, which must be in the same format
as an fsck.skipList. This option may be repeated, and these files
will be processed after any files specified with the
blame.ignoreRevsFile config option. An empty file name, "", will
clear the list of revs from previously processed files.

--color-lines
Color line annotations in the default format differently if they
come from the same commit as the preceding line. This makes it
easier to distinguish code blocks introduced by different
commits. The color defaults to cyan and can be adjusted using the
color.blame.repeatedLines config option.

--color-by-age
Color line annotations depending on the age of the line in the
default format. The color.blame.highlightRecent config option
controls what color is used for each range of age.

-h
Show help message.

-c
Use the same output mode as git-annotate(1) (Default: off).

--score-debug
Include debugging information related to the movement of lines
between files (see -C) and lines moved within a file (see -M).
The first number listed is the score. This is the number of
alphanumeric characters detected as having been moved between or
within files. This must be above a certain threshold for git
blame to consider those lines of code to have been moved.

-f, --show-name
Show the filename in the original commit. By default the filename
is shown if there is any line that came from a file with a
different name, due to rename detection.

-n, --show-number
Show the line number in the original commit (Default: off).

-s
Suppress the author name and timestamp from the output.

-e, --show-email
Show the author email instead of the author name (Default: off).
This can also be controlled via the blame.showEmail config
option.

-w
Ignore whitespace when comparing the parent's version and the
child's to find where the lines came from.

--abbrev=<n>
Instead of using the default 7+1 hexadecimal digits as the
abbreviated object name, use <m>+1 digits, where <m> is at least
<n> but ensures the commit object names are unique. Note that 1
column is used for a caret to mark the boundary commit.

THE DEFAULT FORMAT

When neither --porcelain nor --incremental option is specified, git
blame will output annotation for each line with:

+o abbreviated object name for the commit the line came from;

+o author ident (by default the author name and date, unless -s or
-e is specified); and

+o line number

before the line contents.

THE PORCELAIN FORMAT

In this format, each line is output after a header; the header at the
minimum has the first line which has:

+o 40-byte SHA-1 of the commit the line is attributed to;

+o the line number of the line in the original file;

+o the line number of the line in the final file;

+o on a line that starts a group of lines from a different commit
than the previous one, the number of lines in this group. On
subsequent lines this field is absent.

This header line is followed by the following information at least
once for each commit:

+o the author name ("author"), email ("author-mail"), time
("author-time"), and time zone ("author-tz"); similarly for
committer.

+o the filename in the commit that the line is attributed to.

+o the first line of the commit log message ("summary").

The contents of the actual line are output after the above header,
prefixed by a TAB. This is to allow adding more header elements
later.

The porcelain format generally suppresses commit information that has
already been seen. For example, two lines that are blamed to the same
commit will both be shown, but the details for that commit will be
shown only once. This is more efficient, but may require more state
be kept by the reader. The --line-porcelain option can be used to
output full commit information for each line, allowing simpler (but
less efficient) usage like:

# count the number of lines attributed to each author
git blame --line-porcelain file |
sed -n 's/^author //p' |
sort | uniq -c | sort -rn

SPECIFYING RANGES

Unlike git blame and git annotate in older versions of git, the
extent of the annotation can be limited to both line ranges and
revision ranges. The -L option, which limits annotation to a range of
lines, may be specified multiple times.

When you are interested in finding the origin for lines 40-60 for
file foo, you can use the -L option like so (they mean the same thing
-- both ask for 21 lines starting at line 40):

git blame -L 40,60 foo
git blame -L 40,+21 foo

Also you can use a regular expression to specify the line range:

git blame -L '/^sub hello {/,/^}$/' foo

which limits the annotation to the body of the hello subroutine.

When you are not interested in changes older than version v2.6.18, or
changes older than 3 weeks, you can use revision range specifiers
similar to git rev-list:

git blame v2.6.18.. -- foo
git blame --since=3.weeks -- foo

When revision range specifiers are used to limit the annotation,
lines that have not changed since the range boundary (either the
commit v2.6.18 or the most recent commit that is more than 3 weeks
old in the above example) are blamed for that range boundary commit.

A particularly useful way is to see if an added file has lines
created by copy-and-paste from existing files. Sometimes this
indicates that the developer was being sloppy and did not refactor
the code properly. You can first find the commit that introduced the
file with:

git log --diff-filter=A --pretty=short -- foo

and then annotate the change between the commit and its parents,
using commit^! notation:

git blame -C -C -f $commit^! -- foo

INCREMENTAL OUTPUT

When called with --incremental option, the command outputs the result
as it is built. The output generally will talk about lines touched by
more recent commits first (i.e. the lines will be annotated out of
order) and is meant to be used by interactive viewers.

The output format is similar to the Porcelain format, but it does not
contain the actual lines from the file that is being annotated.

1. Each blame entry always starts with a line of:

<40-byte-hex-sha1> <sourceline> <resultline> <num-lines>

Line numbers count from 1.

2. The first time that a commit shows up in the stream, it has
various other information about it printed out with a one-word
tag at the beginning of each line describing the extra commit
information (author, email, committer, dates, summary, etc.).

3. Unlike the Porcelain format, the filename information is always
given and terminates the entry:

"filename" <whitespace-quoted-filename-goes-here>

and thus it is really quite easy to parse for some line- and
word-oriented parser (which should be quite natural for most
scripting languages).

Note
For people who do parsing: to make it more robust, just
ignore any lines between the first and last one ("<sha1>" and
"filename" lines) where you do not recognize the tag words
(or care about that particular one) at the beginning of the
"extended information" lines. That way, if there is ever
added information (like the commit encoding or extended
commit commentary), a blame viewer will not care.

MAPPING AUTHORS

See gitmailmap(5).

CONFIGURATION

Everything below this line in this section is selectively included
from the git-config(1) documentation. The content is the same as
what's found there:

blame.blankBoundary
Show blank commit object name for boundary commits in git-
blame(1). This option defaults to false.

blame.coloring
This determines the coloring scheme to be applied to blame
output. It can be repeatedLines, highlightRecent, or none which
is the default.

blame.date
Specifies the format used to output dates in git-blame(1). If
unset the iso format is used. For supported values, see the
discussion of the --date option at git-log(1).

blame.showEmail
Show the author email instead of author name in git-blame(1).
This option defaults to false.

blame.showRoot
Do not treat root commits as boundaries in git-blame(1). This
option defaults to false.

blame.ignoreRevsFile
Ignore revisions listed in the file, one unabbreviated object
name per line, in git-blame(1). Whitespace and comments beginning
with # are ignored. This option may be repeated multiple times.
Empty file names will reset the list of ignored revisions. This
option will be handled before the command line option
--ignore-revs-file.

blame.markUnblamableLines
Mark lines that were changed by an ignored revision that we could
not attribute to another commit with a * in the output of git-
blame(1).

blame.markIgnoredLines
Mark lines that were changed by an ignored revision that we
attributed to another commit with a ? in the output of git-
blame(1).

SEE ALSO

git-annotate(1)

GIT

Part of the git(1) suite

Git 2.48.1 2025-01-13 GIT-BLAME(1)