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[git/git.git] / Documentation / git-describe.txt
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 'git-describe' [--all] [--tags] [--abbrev=<n>] <committish>...
12
13 DESCRIPTION
14 -----------
15 The command finds the most recent tag that is reachable from a
16 commit, and if the commit itself is pointed at by the tag, shows
17 the tag. Otherwise, it suffixes the tag name with the number of
18 additional commits and the abbreviated object name of the commit.
19
20
21 OPTIONS
22 -------
23 <committish>::
24 The object name of the committish.
25
26 --all::
27 Instead of using only the annotated tags, use any ref
28 found in `.git/refs/`.
29
30 --tags::
31 Instead of using only the annotated tags, use any tag
32 found in `.git/refs/tags`.
33
34 --abbrev=<n>::
35 Instead of using the default 8 hexadecimal digits as the
36 abbreviated object name, use <n> digits.
37
38 --candidates=<n>::
39 Instead of considering only the 10 most recent tags as
40 candidates to describe the input committish consider
41 up to <n> candidates. Increasing <n> above 10 will take
42 slightly longer but may produce a more accurate result.
43
44 --debug::
45 Verbosely display information about the searching strategy
46 being employed to standard error. The tag name will still
47 be printed to standard out.
48
49 EXAMPLES
50 --------
51
52 With something like git.git current tree, I get:
53
54 [torvalds@g5 git]$ git-describe parent
55 v1.0.4-14-g2414721
56
57 i.e. the current head of my "parent" branch is based on v1.0.4,
58 but since it has a handful commits on top of that,
59 describe has added the number of additional commits ("14") and
60 an abbreviated object name for the commit itself ("2414721")
61 at the end.
62
63 The number of additional commits is the number
64 of commits which would be displayed by "git log v1.0.4..parent".
65 The hash suffix is "-g" + 7-char abbreviation for the tip commit
66 of parent (which was `2414721b194453f058079d897d13c4e377f92dc6`).
67
68 Doing a "git-describe" on a tag-name will just show the tag name:
69
70 [torvalds@g5 git]$ git-describe v1.0.4
71 v1.0.4
72
73 With --all, the command can use branch heads as references, so
74 the output shows the reference path as well:
75
76 [torvalds@g5 git]$ git describe --all --abbrev=4 v1.0.5^2
77 tags/v1.0.0-21-g975b
78
79 [torvalds@g5 git]$ git describe --all HEAD^
80 heads/lt/describe-7-g975b
81
82 With --abbrev set to 0, the command can be used to find the
83 closest tagname without any suffix:
84
85 [torvalds@g5 git]$ git describe --abbrev=0 v1.0.5^2
86 tags/v1.0.0
87
88 SEARCH STRATEGY
89 ---------------
90
91 For each committish supplied "git describe" will first look for
92 a tag which tags exactly that commit. Annotated tags will always
93 be preferred over lightweight tags, and tags with newer dates will
94 always be preferred over tags with older dates. If an exact match
95 is found, its name will be output and searching will stop.
96
97 If an exact match was not found "git describe" will walk back
98 through the commit history to locate an ancestor commit which
99 has been tagged. The ancestor's tag will be output along with an
100 abbreviation of the input committish's SHA1.
101
102 If multiple tags were found during the walk then the tag which
103 has the fewest commits different from the input committish will be
104 selected and output. Here fewest commits different is defined as
105 the number of commits which would be shown by "git log tag..input"
106 will be the smallest number of commits possible.
107
108
109 Author
110 ------
111 Written by Linus Torvalds <torvalds@osdl.org>, but somewhat
112 butchered by Junio C Hamano <junkio@cox.net>. Later significantly
113 updated by Shawn Pearce <spearce@spearce.org>.
114
115 Documentation
116 --------------
117 Documentation by David Greaves, Junio C Hamano and the git-list <git@vger.kernel.org>.
118
119 GIT
120 ---
121 Part of the gitlink:git[7] suite
122