git-blame(1) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | THE PORCELAIN FORMAT | SPECIFYING RANGES | INCREMENTAL OUTPUT | MAPPING AUTHORS | SEE ALSO | GIT | COLOPHON

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

NAME         top

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

SYNOPSIS         top

       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>]
                   [--progress] [--abbrev=<n>] [<rev> | --contents <file> | --reverse <rev>..<rev>]
                   [--] <file>

DESCRIPTION         top

       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         top

       -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:

           •   number

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

           •   /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>.

           •   +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>
           When <rev> is not specified, the command annotates the
           changes starting backwards from the working tree copy. This
           flag makes the command pretend as if the working tree copy
           has the contents of the named file (specify - to make the
           command read from the standard input).

       --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.

       -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 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 PORCELAIN FORMAT         top

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

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

       •   the line number of the line in the original file;

       •   the line number of the line in the final file;

       •   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:

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

       •   the filename in the commit that the line is attributed to.

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

       The contents of the actual line is 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         top

       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         top

       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         top

       See gitmailmap(5).

SEE ALSO         top

       git-annotate(1)

GIT         top

       Part of the git(1) suite

COLOPHON         top

       This page is part of the git (Git distributed version control
       system) project.  Information about the project can be found at
       ⟨http://git-scm.com/⟩.  If you have a bug report for this manual
       page, see ⟨http://git-scm.com/community⟩.  This page was obtained
       from the project's upstream Git repository
       ⟨https://github.com/git/git.git⟩ on 2021-08-27.  (At that time,
       the date of the most recent commit that was found in the
       repository was 2021-08-24.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

Git 2.33.0.69.gc420321         08/27/2021                   GIT-BLAME(1)

Pages that refer to this page: git(1)git-annotate(1)git-bisect(1)git-config(1)git-diff-tree(1)git-log(1)git-rev-list(1)git-show(1)gitweb.conf(5)gitworkflows(7)