NAME
----
-git-blame - Blame file lines on commits
+git-blame - Show what revision and author last modified each line of a file
SYNOPSIS
--------
-git-blame file [options] file [revision]
+[verse]
+'git-blame' [-c] [-l] [-t] [-f] [-n] [-p] [--incremental] [-L n,m] [-S <revs-file>]
+ [-M] [-C] [-C] [--since=<date>] [<rev>] [--] <file>
DESCRIPTION
-----------
-Annotates each line in the given file with information from the commit
-which introduced the line. Start annotation from the given revision.
+
+Annotates each line in the given file with information from the revision which
+last modified the line. Optionally, start annotating from the given revision.
+
+Also it can limit the range of lines annotated.
+
+This report doesn't tell you anything about lines which have been deleted or
+replaced; you need to use a tool such as gitlink:git-diff[1] 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 <ancestry-file>
+ea4c7f9bf69e781dd0cd88d2bccb2bf5cc15c9a7 git-blame: Make the output
+-----------------------------------------------------------------------------
OPTIONS
-------
-c, --compatibility::
- Use the same output mode as git-annotate (Default: off).
+ Use the same output mode as gitlink:git-annotate[1] (Default: off).
+
+-L n,m::
+ Annotate only the specified line range (lines count from 1).
-l, --long::
Show long rev (Default: off).
Show raw timestamp (Default: off).
-S, --rev-file <revs-file>::
- Use revs from revs-file instead of calling git-rev-list.
+ Use revs from revs-file instead of calling gitlink:git-rev-list[1].
+
+-f, --show-name::
+ Show filename in the original commit. By default
+ filename is shown if there is any line that came from a
+ file with different name, due to rename detection.
+
+-n, --show-number::
+ Show line number in the original commit (Default: off).
+
+-p, --porcelain::
+ Show in a format designed for machine consumption.
+
+--incremental::
+ Show the result incrementally in a format designed for
+ machine consumption.
+
+-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), 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.
+
+-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 looks for copies from all other files in the
+ parent for the commit that creates the file in addition.
-h, --help::
Show help message.
+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 line 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:
+
+- author name ("author"), email ("author-mail"), time
+ ("author-time"), and timezone ("author-tz"); similarly
+ for committer.
+- filename in the commit 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 git, the extent
+of annotation can be limited to both line ranges and revision
+ranges. When you are interested in finding the origin for
+ll. 40-60 for file `foo`, you can use `-L` option like these
+(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 regular expression to specify the line range.
+
+ git blame -L '/^sub hello {/,/^}$/' foo
+
+would limit the annotation to the body of `hello` subroutine.
+
+When you are not interested in changes older than the 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 have 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{caret}!` 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.
+
+. Each blame entry always starts with a line of:
+
+ <40-byte hex sha1> <sourceline> <resultline> <num_lines>
++
+Line numbers count from 1.
+
+. The first time that 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 about that "extended commit info" (author,
+ email, committer, dates, summary etc).
+
+. Unlike Porcelain format, the filename information is always
+ given and terminates the entry:
+
+ "filename" <whitespace-quoted-filename-goes-here>
++
+and thus it's 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 in between the first and last one ("<sha1>" and "filename" lines)
+where you don't 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 won't ever care.
+
+
SEE ALSO
--------
gitlink:git-annotate[1]
AUTHOR
------
-Written by Fredrik Kuivinen <freku045@student.liu.se>.
+Written by Junio C Hamano <junkio@cox.net>
GIT
---