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

       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 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

       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).


SEE ALSO

       git-annotate(1)


GIT

       Part of the git(1) suite



Git 2.31.0                        03/15/2021                      git-blame(1)

git 2.31.0 - Generated Tue Mar 16 20:23:03 CDT 2021
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