[thirdparty/git.git] / Documentation / git-describe.txt

git-describe(1)
===============

NAME
----
git-describe - Show the most recent tag that is reachable from a commit


SYNOPSIS
--------
[verse]
'git describe' [--all] [--tags] [--contains] [--abbrev=<n>] <committish>...
'git describe' [--all] [--tags] [--contains] [--abbrev=<n>] --dirty[=<mark>]

DESCRIPTION
-----------
The command finds the most recent tag that is reachable from a
commit.  If the tag points to the commit, then only the tag is
shown.  Otherwise, it suffixes the tag name with the number of
additional commits on top of the tagged object and the
abbreviated object name of the most recent commit.

By default (without --all or --tags) `git describe` only shows
annotated tags.  For more information about creating annotated tags
see the -a and -s options to linkgit:git-tag[1].

OPTIONS
-------
<committish>...::
	Committish object names to describe.

--dirty[=<mark>]::
	Describe the working tree.
	It means describe HEAD and appends <mark> (`-dirty` by
	default) if the working tree is dirty.

--all::
	Instead of using only the annotated tags, use any ref
	found in `.git/refs/`.  This option enables matching
	any known branch, remote branch, or lightweight tag.

--tags::
	Instead of using only the annotated tags, use any tag
	found in `.git/refs/tags`.  This option enables matching
	a lightweight (non-annotated) tag.

--contains::
	Instead of finding the tag that predates the commit, find
	the tag that comes after the commit, and thus contains it.
	Automatically implies --tags.

--abbrev=<n>::
	Instead of using the default 7 hexadecimal digits as the
	abbreviated object name, use <n> digits, or as many digits
	as needed to form a unique object name.  An <n> of 0
	will suppress long format, only showing the closest tag.

--candidates=<n>::
	Instead of considering only the 10 most recent tags as
	candidates to describe the input committish consider
	up to <n> candidates.  Increasing <n> above 10 will take
	slightly longer but may produce a more accurate result.
	An <n> of 0 will cause only exact matches to be output.

--exact-match::
	Only output exact matches (a tag directly references the
	supplied commit).  This is a synonym for --candidates=0.

--debug::
	Verbosely display information about the searching strategy
	being employed to standard error.  The tag name will still
	be printed to standard out.

--long::
	Always output the long format (the tag, the number of commits
	and the abbreviated commit name) even when it matches a tag.
	This is useful when you want to see parts of the commit object name
	in "describe" output, even when the commit in question happens to be
	a tagged version.  Instead of just emitting the tag name, it will
	describe such a commit as v1.2-0-gdeadbee (0th commit since tag v1.2
	that points at object deadbee....).

--match <pattern>::
	Only consider tags matching the given pattern (can be used to avoid
	leaking private tags made from the repository).

--always::
	Show uniquely abbreviated commit object as fallback.

EXAMPLES
--------

With something like git.git current tree, I get:

	[torvalds@g5 git]$ git describe parent
	v1.0.4-14-g2414721

i.e. the current head of my "parent" branch is based on v1.0.4,
but since it has a few commits on top of that,
describe has added the number of additional commits ("14") and
an abbreviated object name for the commit itself ("2414721")
at the end.

The number of additional commits is the number
of commits which would be displayed by "git log v1.0.4..parent".
The hash suffix is "-g" + 7-char abbreviation for the tip commit
of parent (which was `2414721b194453f058079d897d13c4e377f92dc6`).

Doing a 'git describe' on a tag-name will just show the tag name:

	[torvalds@g5 git]$ git describe v1.0.4
	v1.0.4

With --all, the command can use branch heads as references, so
the output shows the reference path as well:

	[torvalds@g5 git]$ git describe --all --abbrev=4 v1.0.5^2
	tags/v1.0.0-21-g975b

	[torvalds@g5 git]$ git describe --all --abbrev=4 HEAD^
	heads/lt/describe-7-g975b

With --abbrev set to 0, the command can be used to find the
closest tagname without any suffix:

	[torvalds@g5 git]$ git describe --abbrev=0 v1.0.5^2
	tags/v1.0.0

Note that the suffix you get if you type these commands today may be
longer than what Linus saw above when he ran these commands, as your
git repository may have new commits whose object names begin with
975b that did not exist back then, and "-g975b" suffix alone may not
be sufficient to disambiguate these commits.


SEARCH STRATEGY
---------------

For each committish supplied, 'git describe' will first look for
a tag which tags exactly that commit.  Annotated tags will always
be preferred over lightweight tags, and tags with newer dates will
always be preferred over tags with older dates.  If an exact match
is found, its name will be output and searching will stop.

If an exact match was not found, 'git describe' will walk back
through the commit history to locate an ancestor commit which
has been tagged.  The ancestor's tag will be output along with an
abbreviation of the input committish's SHA1.

If multiple tags were found during the walk then the tag which
has the fewest commits different from the input committish will be
selected and output.  Here fewest commits different is defined as
the number of commits which would be shown by `git log tag..input`
will be the smallest number of commits possible.


Author
------
Written by Linus Torvalds <torvalds@osdl.org>, but somewhat
butchered by Junio C Hamano <gitster@pobox.com>.  Later significantly
updated by Shawn Pearce <spearce@spearce.org>.

Documentation
--------------
Documentation by David Greaves, Junio C Hamano and the git-list <git@vger.kernel.org>.

GIT
---
Part of the linkgit:git[1] suite
Commit	Line	Data
	1	git-describe(1)
	2	===============
	3
	4	NAME
	5	----
	6	git-describe - Show the most recent tag that is reachable from a commit
	7
	8
	9	SYNOPSIS
	10	--------
	11	[verse]
	12	'git describe' [--all] [--tags] [--contains] [--abbrev=<n>] <committish>...
	13	'git describe' [--all] [--tags] [--contains] [--abbrev=<n>] --dirty[=<mark>]
	14
	15	DESCRIPTION
	16	-----------
	17	The command finds the most recent tag that is reachable from a
	18	commit. If the tag points to the commit, then only the tag is
	19	shown. Otherwise, it suffixes the tag name with the number of
	20	additional commits on top of the tagged object and the
	21	abbreviated object name of the most recent commit.
	22
	23	By default (without --all or --tags) `git describe` only shows
	24	annotated tags. For more information about creating annotated tags
	25	see the -a and -s options to linkgit:git-tag[1].
	26
	27	OPTIONS
	28	-------
	29	<committish>...::
	30	Committish object names to describe.
	31
	32	--dirty[=<mark>]::
	33	Describe the working tree.
	34	It means describe HEAD and appends <mark> (`-dirty` by
	35	default) if the working tree is dirty.
	36
	37	--all::
	38	Instead of using only the annotated tags, use any ref
	39	found in `.git/refs/`. This option enables matching
	40	any known branch, remote branch, or lightweight tag.
	41
	42	--tags::
	43	Instead of using only the annotated tags, use any tag
	44	found in `.git/refs/tags`. This option enables matching
	45	a lightweight (non-annotated) tag.
	46
	47	--contains::
	48	Instead of finding the tag that predates the commit, find
	49	the tag that comes after the commit, and thus contains it.
	50	Automatically implies --tags.
	51
	52	--abbrev=<n>::
	53	Instead of using the default 7 hexadecimal digits as the
	54	abbreviated object name, use <n> digits, or as many digits
	55	as needed to form a unique object name. An <n> of 0
	56	will suppress long format, only showing the closest tag.
	57
	58	--candidates=<n>::
	59	Instead of considering only the 10 most recent tags as
	60	candidates to describe the input committish consider
	61	up to <n> candidates. Increasing <n> above 10 will take
	62	slightly longer but may produce a more accurate result.
	63	An <n> of 0 will cause only exact matches to be output.
	64
	65	--exact-match::
	66	Only output exact matches (a tag directly references the
	67	supplied commit). This is a synonym for --candidates=0.
	68
	69	--debug::
	70	Verbosely display information about the searching strategy
	71	being employed to standard error. The tag name will still
	72	be printed to standard out.
	73
	74	--long::
	75	Always output the long format (the tag, the number of commits
	76	and the abbreviated commit name) even when it matches a tag.
	77	This is useful when you want to see parts of the commit object name
	78	in "describe" output, even when the commit in question happens to be
	79	a tagged version. Instead of just emitting the tag name, it will
	80	describe such a commit as v1.2-0-gdeadbee (0th commit since tag v1.2
	81	that points at object deadbee....).
	82
	83	--match <pattern>::
	84	Only consider tags matching the given pattern (can be used to avoid
	85	leaking private tags made from the repository).
	86
	87	--always::
	88	Show uniquely abbreviated commit object as fallback.
	89
	90	EXAMPLES
	91	--------
	92
	93	With something like git.git current tree, I get:
	94
	95	[torvalds@g5 git]$ git describe parent
	96	v1.0.4-14-g2414721
	97
	98	i.e. the current head of my "parent" branch is based on v1.0.4,
	99	but since it has a few commits on top of that,
	100	describe has added the number of additional commits ("14") and
	101	an abbreviated object name for the commit itself ("2414721")
	102	at the end.
	103
	104	The number of additional commits is the number
	105	of commits which would be displayed by "git log v1.0.4..parent".
	106	The hash suffix is "-g" + 7-char abbreviation for the tip commit
	107	of parent (which was `2414721b194453f058079d897d13c4e377f92dc6`).
	108
	109	Doing a 'git describe' on a tag-name will just show the tag name:
	110
	111	[torvalds@g5 git]$ git describe v1.0.4
	112	v1.0.4
	113
	114	With --all, the command can use branch heads as references, so
	115	the output shows the reference path as well:
	116
	117	[torvalds@g5 git]$ git describe --all --abbrev=4 v1.0.5^2
	118	tags/v1.0.0-21-g975b
	119
	120	[torvalds@g5 git]$ git describe --all --abbrev=4 HEAD^
	121	heads/lt/describe-7-g975b
	122
	123	With --abbrev set to 0, the command can be used to find the
	124	closest tagname without any suffix:
	125
	126	[torvalds@g5 git]$ git describe --abbrev=0 v1.0.5^2
	127	tags/v1.0.0
	128
	129	Note that the suffix you get if you type these commands today may be
	130	longer than what Linus saw above when he ran these commands, as your
	131	git repository may have new commits whose object names begin with
	132	975b that did not exist back then, and "-g975b" suffix alone may not
	133	be sufficient to disambiguate these commits.
	134
	135
	136	SEARCH STRATEGY
	137	---------------
	138
	139	For each committish supplied, 'git describe' will first look for
	140	a tag which tags exactly that commit. Annotated tags will always
	141	be preferred over lightweight tags, and tags with newer dates will
	142	always be preferred over tags with older dates. If an exact match
	143	is found, its name will be output and searching will stop.
	144
	145	If an exact match was not found, 'git describe' will walk back
	146	through the commit history to locate an ancestor commit which
	147	has been tagged. The ancestor's tag will be output along with an
	148	abbreviation of the input committish's SHA1.
	149
	150	If multiple tags were found during the walk then the tag which
	151	has the fewest commits different from the input committish will be
	152	selected and output. Here fewest commits different is defined as
	153	the number of commits which would be shown by `git log tag..input`
	154	will be the smallest number of commits possible.
	155
	156
	157	Author
	158	------
	159	Written by Linus Torvalds <torvalds@osdl.org>, but somewhat
	160	butchered by Junio C Hamano <gitster@pobox.com>. Later significantly
	161	updated by Shawn Pearce <spearce@spearce.org>.
	162
	163	Documentation
	164	--------------
	165	Documentation by David Greaves, Junio C Hamano and the git-list <git@vger.kernel.org>.
	166
	167	GIT
	168	---
	169	Part of the linkgit:git[1] suite