git-blame

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] [-p] [-w] [--incremental] [-L n,m]
                   [-S ] [-M] [-C] [-C] [-C] [--since=]
                   [ | --contents  | --reverse ] [--] 


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.

       The command can also limit the range of lines annotated.

       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:

           $ git log --pretty=oneline -S'blame_usage'
           5040f17eba15504bad66b14a645bddd9b015ebb7 blame -S 
           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 ,
           Annotate only the given line range.  and  can take one
           of these forms:

           ·   number

               If  or  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  is a regex, it will search starting at the line
               given by .

           ·   +offset or -offset

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

       -l
           Show long rev (Default: off).

       -t
           Show raw timestamp (Default: off).

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

       --reverse
           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.

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

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

       --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 
           When  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 
           The value is one of the following alternatives:
           {relative,local,default,iso,rfc,short}. 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 more information, See the discussion of the --date option at
           git-log(1).

       -M||
           Detect moving lines in the file as well. When a commit moves a
           block of lines in a file (e.g. the original file has A and then B,
           and the commit changes it to B and then A), the traditional blame
           algorithm 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.

            is optional but it is the lower bound on the number of
           alphanumeric characters that git must detect as moving within a
           file for it to associate those lines with the parent commit.

       -C||
           In addition to -M, detect lines 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.

            is optional but it is the lower bound on the number of
           alphanumeric characters that git must detect as moving between
           files for it to associate those lines with the parent commit.

       -h, --help
           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.

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

THE PORCELAIN FORMAT
       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 timezone ("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.

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. 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>   

           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" 

           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 ("" 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
       If the file .mailmap exists at the toplevel of the repository, or at
       the location pointed to by the mailmap.file configuration option, it is
       used to map author and committer names and email addresses to canonical
       real names and email addresses.

       In the simple form, each line in the file consists of the canonical
       real name of an author, whitespace, and an email address used in the
       commit (enclosed by < and >) to map to the name. For example:

           Proper Name 

       The more complex forms are:

            

       which allows mailmap to replace only the email part of a commit, and:

           Proper Name  

       which allows mailmap to replace both the name and the email of a commit
       matching the specified commit email address, and:

           Proper Name  Commit Name 

       which allows mailmap to replace both the name and the email of a commit
       matching both the specified commit name and email address.

       Example 1: Your history contains commits by two authors, Jane and Joe,
       whose names appear in the repository under several forms:

           Joe Developer 
           Joe R. Developer 
           Jane Doe 
           Jane Doe 
           Jane D. 


       Now suppose that Joe wants his middle name initial used, and Jane
       prefers her family name fully spelled out. A proper .mailmap file would
       look like:

           Jane Doe         
           Joe R. Developer 


       Note how there is no need for an entry for ,
       because the real name of that author is already correct.

       Example 2: Your repository contains commits from the following authors:

           nick1 
           nick2 
           nick2 
           santa 
           claus 
           CTO 


       Then you might want a .mailmap file that looks like:

                                  
           Some Dude          nick1 
           Other Author    nick2 
           Other Author          
           Santa Claus  


       Use hash # for comments that are either on their own line, or after the
       email address.

SEE ALSO
       git-annotate(1)

AUTHOR
       Written by Junio C Hamano 

GIT
       Part of the git(1) suite

NOTES
        1. jane@laptop
           mailto:jane@laptop

        2. gitster@pobox.com
           mailto:gitster@pobox.com



Git 1.7.0.4                       12/03/2010                      GIT-BLAME(1)