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1a3119ed06
The --contents option can be used with git blame to blame the file as if
it had the contents from the specified file. This is akin to copying the
contents into the working tree and then running git blame. This option
has been supported since 1cfe77333f ("git-blame: no rev means start
from the working tree file.")
The --contents option always blames the file as if it was based on the
current HEAD commit. If you try to pass a revision while using
--contents, you get the following error:
fatal: cannot use --contents with final commit object name
This is because the blame process generates a fake working tree commit
which always uses the HEAD object as its sole parent.
Enhance fake_working_tree_commit to take the object ID to use for the
parent instead of always using the HEAD object. Then, always generate a
fake commit when we have contents provided, even if we have a final
object. Remove the check to disallow --contents and a final revision.
Note that the behavior of generating a fake working commit is still
skipped when a revision is provided but --contents is not provided.
Generating such a commit in that case would combine the currently
checked out file contents with the provided revision, which breaks
normal blame behavior and produces unexpected results.
This enables use of --contents with an arbitrary revision, rather than
forcing the use of the local HEAD commit. This makes the --contents
option significantly more flexible, as it is no longer required to check
out the working tree to the desired commit before using --contents.
Reword the documentation so that its clear that --contents can be used
with <rev>.
Add tests for the --contents option to the annotate-tests.sh test
script.
Signed-off-by: Jacob Keller <jacob.keller@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
258 lines
8.5 KiB
Plaintext
258 lines
8.5 KiB
Plaintext
git-blame(1)
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============
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NAME
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----
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git-blame - Show what revision and author last modified each line of a file
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SYNOPSIS
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--------
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[verse]
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'git blame' [-c] [-b] [-l] [--root] [-t] [-f] [-n] [-s] [-e] [-p] [-w] [--incremental]
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[-L <range>] [-S <revs-file>] [-M] [-C] [-C] [-C] [--since=<date>]
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[--ignore-rev <rev>] [--ignore-revs-file <file>]
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[--color-lines] [--color-by-age] [--progress] [--abbrev=<n>]
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[ --contents <file> ] [<rev> | --reverse <rev>..<rev>] [--] <file>
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DESCRIPTION
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-----------
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Annotates each line in the given file with information from the revision which
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last modified the line. Optionally, start annotating from the given revision.
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When specified one or more times, `-L` restricts annotation to the requested
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lines.
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The origin of lines is automatically followed across whole-file
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renames (currently there is no option to turn the rename-following
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off). To follow lines moved from one file to another, or to follow
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lines that were copied and pasted from another file, etc., see the
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`-C` and `-M` options.
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The report does not tell you anything about lines which have been deleted or
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replaced; you need to use a tool such as 'git diff' or the "pickaxe"
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interface briefly mentioned in the following paragraph.
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Apart from supporting file annotation, Git also supports searching the
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development history for when a code snippet occurred in a change. This makes it
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possible to track when a code snippet was added to a file, moved or copied
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between files, and eventually deleted or replaced. It works by searching for
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a text string in the diff. A small example of the pickaxe interface
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that searches for `blame_usage`:
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-----------------------------------------------------------------------------
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$ git log --pretty=oneline -S'blame_usage'
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5040f17eba15504bad66b14a645bddd9b015ebb7 blame -S <ancestry-file>
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ea4c7f9bf69e781dd0cd88d2bccb2bf5cc15c9a7 git-blame: Make the output
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-----------------------------------------------------------------------------
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OPTIONS
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-------
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include::blame-options.txt[]
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-c::
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Use the same output mode as linkgit:git-annotate[1] (Default: off).
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--score-debug::
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Include debugging information related to the movement of
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lines between files (see `-C`) and lines moved within a
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file (see `-M`). The first number listed is the score.
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This is the number of alphanumeric characters detected
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as having been moved between or within files. This must be above
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a certain threshold for 'git blame' to consider those lines
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of code to have been moved.
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-f::
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--show-name::
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Show the filename in the original commit. By default
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the filename is shown if there is any line that came from a
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file with a different name, due to rename detection.
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-n::
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--show-number::
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Show the line number in the original commit (Default: off).
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-s::
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Suppress the author name and timestamp from the output.
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-e::
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--show-email::
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Show the author email instead of author name (Default: off).
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This can also be controlled via the `blame.showEmail` config
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option.
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-w::
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Ignore whitespace when comparing the parent's version and
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the child's to find where the lines came from.
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--abbrev=<n>::
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Instead of using the default 7+1 hexadecimal digits as the
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abbreviated object name, use <m>+1 digits, where <m> is at
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least <n> but ensures the commit object names are unique.
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Note that 1 column
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is used for a caret to mark the boundary commit.
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THE DEFAULT FORMAT
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------------------
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When neither `--porcelain` nor `--incremental` option is specified,
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`git blame` will output annotation for each line with:
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- abbreviated object name for the commit the line came from;
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- author ident (by default author name and date, unless `-s` or `-e`
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is specified); and
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- line number
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before the line contents.
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THE PORCELAIN FORMAT
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--------------------
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In this format, each line is output after a header; the
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header at the minimum has the first line which has:
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- 40-byte SHA-1 of the commit the line is attributed to;
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- the line number of the line in the original file;
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- the line number of the line in the final file;
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- on a line that starts a group of lines from a different
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commit than the previous one, the number of lines in this
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group. On subsequent lines this field is absent.
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This header line is followed by the following information
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at least once for each commit:
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- the author name ("author"), email ("author-mail"), time
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("author-time"), and time zone ("author-tz"); similarly
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for committer.
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- the filename in the commit that the line is attributed to.
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- the first line of the commit log message ("summary").
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The contents of the actual line is output after the above
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header, prefixed by a TAB. This is to allow adding more
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header elements later.
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The porcelain format generally suppresses commit information that has
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already been seen. For example, two lines that are blamed to the same
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commit will both be shown, but the details for that commit will be shown
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only once. This is more efficient, but may require more state be kept by
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the reader. The `--line-porcelain` option can be used to output full
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commit information for each line, allowing simpler (but less efficient)
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usage like:
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# count the number of lines attributed to each author
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git blame --line-porcelain file |
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sed -n 's/^author //p' |
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sort | uniq -c | sort -rn
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SPECIFYING RANGES
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-----------------
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Unlike 'git blame' and 'git annotate' in older versions of git, the extent
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of the annotation can be limited to both line ranges and revision
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ranges. The `-L` option, which limits annotation to a range of lines, may be
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specified multiple times.
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When you are interested in finding the origin for
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lines 40-60 for file `foo`, you can use the `-L` option like so
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(they mean the same thing -- both ask for 21 lines starting at
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line 40):
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git blame -L 40,60 foo
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git blame -L 40,+21 foo
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Also you can use a regular expression to specify the line range:
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git blame -L '/^sub hello {/,/^}$/' foo
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which limits the annotation to the body of the `hello` subroutine.
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When you are not interested in changes older than version
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v2.6.18, or changes older than 3 weeks, you can use revision
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range specifiers similar to 'git rev-list':
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git blame v2.6.18.. -- foo
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git blame --since=3.weeks -- foo
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When revision range specifiers are used to limit the annotation,
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lines that have not changed since the range boundary (either the
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commit v2.6.18 or the most recent commit that is more than 3
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weeks old in the above example) are blamed for that range
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boundary commit.
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A particularly useful way is to see if an added file has lines
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created by copy-and-paste from existing files. Sometimes this
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indicates that the developer was being sloppy and did not
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refactor the code properly. You can first find the commit that
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introduced the file with:
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git log --diff-filter=A --pretty=short -- foo
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and then annotate the change between the commit and its
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parents, using `commit^!` notation:
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git blame -C -C -f $commit^! -- foo
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INCREMENTAL OUTPUT
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------------------
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When called with `--incremental` option, the command outputs the
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result as it is built. The output generally will talk about
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lines touched by more recent commits first (i.e. the lines will
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be annotated out of order) and is meant to be used by
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interactive viewers.
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The output format is similar to the Porcelain format, but it
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does not contain the actual lines from the file that is being
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annotated.
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. Each blame entry always starts with a line of:
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<40-byte hex sha1> <sourceline> <resultline> <num_lines>
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+
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Line numbers count from 1.
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. The first time that a commit shows up in the stream, it has various
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other information about it printed out with a one-word tag at the
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beginning of each line describing the extra commit information (author,
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email, committer, dates, summary, etc.).
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. Unlike the Porcelain format, the filename information is always
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given and terminates the entry:
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"filename" <whitespace-quoted-filename-goes-here>
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+
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and thus it is really quite easy to parse for some line- and word-oriented
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parser (which should be quite natural for most scripting languages).
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+
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[NOTE]
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For people who do parsing: to make it more robust, just ignore any
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lines between the first and last one ("<sha1>" and "filename" lines)
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where you do not recognize the tag words (or care about that particular
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one) at the beginning of the "extended information" lines. That way, if
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there is ever added information (like the commit encoding or extended
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commit commentary), a blame viewer will not care.
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MAPPING AUTHORS
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---------------
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See linkgit:gitmailmap[5].
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CONFIGURATION
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-------------
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include::includes/cmd-config-section-all.txt[]
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include::config/blame.txt[]
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SEE ALSO
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--------
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linkgit:git-annotate[1]
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GIT
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---
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Part of the linkgit:git[1] suite
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