Documentation/git-describe.txt

   1 git-describe(1)
   2 ===============
   3
   4 NAME
   5 ----
   6 git-describe - Give an object a human readable name based on an available ref
   7
   8 SYNOPSIS
   9 --------
  10 [verse]
  11 'git describe' [--all] [--tags] [--contains] [--abbrev=<n>] [<commit-ish>...]
  12 'git describe' [--all] [--tags] [--contains] [--abbrev=<n>] --dirty[=<mark>]
  13 'git describe' <blob>
  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. The result
  22 is a "human-readable" object name which can also be used to
  23 identify the commit to other git commands.
  24
  25 By default (without --all or --tags) `git describe` only shows
  26 annotated tags.  For more information about creating annotated tags
  27 see the -a and -s options to linkgit:git-tag[1].
  28
  29 If the given object refers to a blob, it will be described
  30 as `<commit-ish>:<path>`, such that the blob can be found
  31 at `<path>` in the `<commit-ish>`, which itself describes the
  32 first commit in which this blob occurs in a reverse revision walk
  33 from HEAD.
  34
  35 OPTIONS
  36 -------
  37 <commit-ish>...::
  38         Commit-ish object names to describe.  Defaults to HEAD if omitted.
  39
  40 --dirty[=<mark>]::
  41 --broken[=<mark>]::
  42         Describe the state of the working tree.  When the working
  43         tree matches HEAD, the output is the same as "git describe
  44         HEAD".  If the working tree has local modification "-dirty"
  45         is appended to it.  If a repository is corrupt and Git
  46         cannot determine if there is local modification, Git will
  47         error out, unless `--broken' is given, which appends
  48         the suffix "-broken" instead.
  49
  50 --all::
  51         Instead of using only the annotated tags, use any ref
  52         found in `refs/` namespace.  This option enables matching
  53         any known branch, remote-tracking branch, or lightweight tag.
  54
  55 --tags::
  56         Instead of using only the annotated tags, use any tag
  57         found in `refs/tags` namespace.  This option enables matching
  58         a lightweight (non-annotated) tag.
  59
  60 --contains::
  61         Instead of finding the tag that predates the commit, find
  62         the tag that comes after the commit, and thus contains it.
  63         Automatically implies --tags.
  64
  65 --abbrev=<n>::
  66         Instead of using the default number of hexadecimal digits (which
  67         will vary according to the number of objects in the repository with
  68         a default of 7) of the abbreviated object name, use <n> digits, or
  69         as many digits as needed to form a unique object name. An <n> of 0
  70         will suppress long format, only showing the closest tag.
  71
  72 --candidates=<n>::
  73         Instead of considering only the 10 most recent tags as
  74         candidates to describe the input commit-ish consider
  75         up to <n> candidates.  Increasing <n> above 10 will take
  76         slightly longer but may produce a more accurate result.
  77         An <n> of 0 will cause only exact matches to be output.
  78
  79 --exact-match::
  80         Only output exact matches (a tag directly references the
  81         supplied commit).  This is a synonym for --candidates=0.
  82
  83 --debug::
  84         Verbosely display information about the searching strategy
  85         being employed to standard error.  The tag name will still
  86         be printed to standard out.
  87
  88 --long::
  89         Always output the long format (the tag, the number of commits
  90         and the abbreviated commit name) even when it matches a tag.
  91         This is useful when you want to see parts of the commit object name
  92         in "describe" output, even when the commit in question happens to be
  93         a tagged version.  Instead of just emitting the tag name, it will
  94         describe such a commit as v1.2-0-gdeadbee (0th commit since tag v1.2
  95         that points at object deadbee....).
  96
  97 --match <pattern>::
  98         Only consider tags matching the given `glob(7)` pattern,
  99         excluding the "refs/tags/" prefix. If used with `--all`, it also
 100         considers local branches and remote-tracking references matching the
 101         pattern, excluding respectively "refs/heads/" and "refs/remotes/"
 102         prefix; references of other types are never considered. If given
 103         multiple times, a list of patterns will be accumulated, and tags
 104         matching any of the patterns will be considered.  Use `--no-match` to
 105         clear and reset the list of patterns.
 106
 107 --exclude <pattern>::
 108         Do not consider tags matching the given `glob(7)` pattern, excluding
 109         the "refs/tags/" prefix. If used with `--all`, it also does not consider
 110         local branches and remote-tracking references matching the pattern,
 111         excluding respectively "refs/heads/" and "refs/remotes/" prefix;
 112         references of other types are never considered. If given multiple times,
 113         a list of patterns will be accumulated and tags matching any of the
 114         patterns will be excluded. When combined with --match a tag will be
 115         considered when it matches at least one --match pattern and does not
 116         match any of the --exclude patterns. Use `--no-exclude` to clear and
 117         reset the list of patterns.
 118
 119 --always::
 120         Show uniquely abbreviated commit object as fallback.
 121
 122 --first-parent::
 123         Follow only the first parent commit upon seeing a merge commit.
 124         This is useful when you wish to not match tags on branches merged
 125         in the history of the target commit.
 126
 127 EXAMPLES
 128 --------
 129
 130 With something like git.git current tree, I get:
 131
 132         [torvalds@g5 git]$ git describe parent
 133         v1.0.4-14-g2414721
 134
 135 i.e. the current head of my "parent" branch is based on v1.0.4,
 136 but since it has a few commits on top of that,
 137 describe has added the number of additional commits ("14") and
 138 an abbreviated object name for the commit itself ("2414721")
 139 at the end.
 140
 141 The number of additional commits is the number
 142 of commits which would be displayed by "git log v1.0.4..parent".
 143 The hash suffix is "-g" + an unambiguous abbreviation for the tip commit
 144 of parent (which was `2414721b194453f058079d897d13c4e377f92dc6`). The
 145 length of the abbreviation scales as the repository grows, using the
 146 approximate number of objects in the repository and a bit of math
 147 around the birthday paradox, and defaults to a minimum of 7.
 148 The "g" prefix stands for "git" and is used to allow describing the version of
 149 a software depending on the SCM the software is managed with. This is useful
 150 in an environment where people may use different SCMs.
 151
 152 Doing a 'git describe' on a tag-name will just show the tag name:
 153
 154         [torvalds@g5 git]$ git describe v1.0.4
 155         v1.0.4
 156
 157 With --all, the command can use branch heads as references, so
 158 the output shows the reference path as well:
 159
 160         [torvalds@g5 git]$ git describe --all --abbrev=4 v1.0.5^2
 161         tags/v1.0.0-21-g975b
 162
 163         [torvalds@g5 git]$ git describe --all --abbrev=4 HEAD^
 164         heads/lt/describe-7-g975b
 165
 166 With --abbrev set to 0, the command can be used to find the
 167 closest tagname without any suffix:
 168
 169         [torvalds@g5 git]$ git describe --abbrev=0 v1.0.5^2
 170         tags/v1.0.0
 171
 172 Note that the suffix you get if you type these commands today may be
 173 longer than what Linus saw above when he ran these commands, as your
 174 Git repository may have new commits whose object names begin with
 175 975b that did not exist back then, and "-g975b" suffix alone may not
 176 be sufficient to disambiguate these commits.
 177
 178
 179 SEARCH STRATEGY
 180 ---------------
 181
 182 For each commit-ish supplied, 'git describe' will first look for
 183 a tag which tags exactly that commit.  Annotated tags will always
 184 be preferred over lightweight tags, and tags with newer dates will
 185 always be preferred over tags with older dates.  If an exact match
 186 is found, its name will be output and searching will stop.
 187
 188 If an exact match was not found, 'git describe' will walk back
 189 through the commit history to locate an ancestor commit which
 190 has been tagged.  The ancestor's tag will be output along with an
 191 abbreviation of the input commit-ish's SHA-1. If `--first-parent` was
 192 specified then the walk will only consider the first parent of each
 193 commit.
 194
 195 If multiple tags were found during the walk then the tag which
 196 has the fewest commits different from the input commit-ish will be
 197 selected and output.  Here fewest commits different is defined as
 198 the number of commits which would be shown by `git log tag..input`
 199 will be the smallest number of commits possible.
 200
 201 BUGS
 202 ----
 203
 204 Tree objects as well as tag objects not pointing at commits, cannot be described.
 205 When describing blobs, the lightweight tags pointing at blobs are ignored,
 206 but the blob is still described as <commit-ish>:<path> despite the lightweight
 207 tag being favorable.
 208
 209 GIT
 210 ---
 211 Part of the linkgit:git[1] suite