describe --contains: default to HEAD when no commit-ish is given
[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 [verse]
12 'git describe' [--all] [--tags] [--contains] [--abbrev=<n>] [<commit-ish>...]
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 <commit-ish>...::
30 Commit-ish object names to describe. Defaults to HEAD if omitted.
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 `refs/` namespace. This option enables matching
40 any known branch, remote-tracking branch, or lightweight tag.
41
42 --tags::
43 Instead of using only the annotated tags, use any tag
44 found in `refs/tags` namespace. 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 commit-ish 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 `glob(7)` pattern,
85 excluding the "refs/tags/" prefix. This can be used to avoid
86 leaking private tags from the repository.
87
88 --always::
89 Show uniquely abbreviated commit object as fallback.
90
91 --first-parent::
92 Follow only the first parent commit upon seeing a merge commit.
93 This is useful when you wish to not match tags on branches merged
94 in the history of the target commit.
95
96 EXAMPLES
97 --------
98
99 With something like git.git current tree, I get:
100
101 [torvalds@g5 git]$ git describe parent
102 v1.0.4-14-g2414721
103
104 i.e. the current head of my "parent" branch is based on v1.0.4,
105 but since it has a few commits on top of that,
106 describe has added the number of additional commits ("14") and
107 an abbreviated object name for the commit itself ("2414721")
108 at the end.
109
110 The number of additional commits is the number
111 of commits which would be displayed by "git log v1.0.4..parent".
112 The hash suffix is "-g" + 7-char abbreviation for the tip commit
113 of parent (which was `2414721b194453f058079d897d13c4e377f92dc6`).
114 The "g" prefix stands for "git" and is used to allow describing the version of
115 a software depending on the SCM the software is managed with. This is useful
116 in an environment where people may use different SCMs.
117
118 Doing a 'git describe' on a tag-name will just show the tag name:
119
120 [torvalds@g5 git]$ git describe v1.0.4
121 v1.0.4
122
123 With --all, the command can use branch heads as references, so
124 the output shows the reference path as well:
125
126 [torvalds@g5 git]$ git describe --all --abbrev=4 v1.0.5^2
127 tags/v1.0.0-21-g975b
128
129 [torvalds@g5 git]$ git describe --all --abbrev=4 HEAD^
130 heads/lt/describe-7-g975b
131
132 With --abbrev set to 0, the command can be used to find the
133 closest tagname without any suffix:
134
135 [torvalds@g5 git]$ git describe --abbrev=0 v1.0.5^2
136 tags/v1.0.0
137
138 Note that the suffix you get if you type these commands today may be
139 longer than what Linus saw above when he ran these commands, as your
140 Git repository may have new commits whose object names begin with
141 975b that did not exist back then, and "-g975b" suffix alone may not
142 be sufficient to disambiguate these commits.
143
144
145 SEARCH STRATEGY
146 ---------------
147
148 For each commit-ish supplied, 'git describe' will first look for
149 a tag which tags exactly that commit. Annotated tags will always
150 be preferred over lightweight tags, and tags with newer dates will
151 always be preferred over tags with older dates. If an exact match
152 is found, its name will be output and searching will stop.
153
154 If an exact match was not found, 'git describe' will walk back
155 through the commit history to locate an ancestor commit which
156 has been tagged. The ancestor's tag will be output along with an
157 abbreviation of the input commit-ish's SHA-1. If '--first-parent' was
158 specified then the walk will only consider the first parent of each
159 commit.
160
161 If multiple tags were found during the walk then the tag which
162 has the fewest commits different from the input commit-ish will be
163 selected and output. Here fewest commits different is defined as
164 the number of commits which would be shown by `git log tag..input`
165 will be the smallest number of commits possible.
166
167 GIT
168 ---
169 Part of the linkgit:git[1] suite