Documentation / git-describe.txton commit sha1_object_info_extended(): expose a bit more info (9a49059)
   1git-describe(1)
   2===============
   3
   4NAME
   5----
   6git-describe - Show the most recent tag that is reachable from a commit
   7
   8
   9SYNOPSIS
  10--------
  11[verse]
  12'git describe' [--all] [--tags] [--contains] [--abbrev=<n>] <committish>...
  13'git describe' [--all] [--tags] [--contains] [--abbrev=<n>] --dirty[=<mark>]
  14
  15DESCRIPTION
  16-----------
  17The command finds the most recent tag that is reachable from a
  18commit.  If the tag points to the commit, then only the tag is
  19shown.  Otherwise, it suffixes the tag name with the number of
  20additional commits on top of the tagged object and the
  21abbreviated object name of the most recent commit.
  22
  23By default (without --all or --tags) `git describe` only shows
  24annotated tags.  For more information about creating annotated tags
  25see the -a and -s options to linkgit:git-tag[1].
  26
  27OPTIONS
  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-tracking 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
  90EXAMPLES
  91--------
  92
  93With something like git.git current tree, I get:
  94
  95        [torvalds@g5 git]$ git describe parent
  96        v1.0.4-14-g2414721
  97
  98i.e. the current head of my "parent" branch is based on v1.0.4,
  99but since it has a few commits on top of that,
 100describe has added the number of additional commits ("14") and
 101an abbreviated object name for the commit itself ("2414721")
 102at the end.
 103
 104The number of additional commits is the number
 105of commits which would be displayed by "git log v1.0.4..parent".
 106The hash suffix is "-g" + 7-char abbreviation for the tip commit
 107of parent (which was `2414721b194453f058079d897d13c4e377f92dc6`).
 108The "g" prefix stands for "git" and is used to allow describing the version of
 109a software depending on the SCM the software is managed with. This is useful
 110in an environment where people may use different SCMs.
 111
 112Doing a 'git describe' on a tag-name will just show the tag name:
 113
 114        [torvalds@g5 git]$ git describe v1.0.4
 115        v1.0.4
 116
 117With --all, the command can use branch heads as references, so
 118the output shows the reference path as well:
 119
 120        [torvalds@g5 git]$ git describe --all --abbrev=4 v1.0.5^2
 121        tags/v1.0.0-21-g975b
 122
 123        [torvalds@g5 git]$ git describe --all --abbrev=4 HEAD^
 124        heads/lt/describe-7-g975b
 125
 126With --abbrev set to 0, the command can be used to find the
 127closest tagname without any suffix:
 128
 129        [torvalds@g5 git]$ git describe --abbrev=0 v1.0.5^2
 130        tags/v1.0.0
 131
 132Note that the suffix you get if you type these commands today may be
 133longer than what Linus saw above when he ran these commands, as your
 134git repository may have new commits whose object names begin with
 135975b that did not exist back then, and "-g975b" suffix alone may not
 136be sufficient to disambiguate these commits.
 137
 138
 139SEARCH STRATEGY
 140---------------
 141
 142For each committish supplied, 'git describe' will first look for
 143a tag which tags exactly that commit.  Annotated tags will always
 144be preferred over lightweight tags, and tags with newer dates will
 145always be preferred over tags with older dates.  If an exact match
 146is found, its name will be output and searching will stop.
 147
 148If an exact match was not found, 'git describe' will walk back
 149through the commit history to locate an ancestor commit which
 150has been tagged.  The ancestor's tag will be output along with an
 151abbreviation of the input committish's SHA1.
 152
 153If multiple tags were found during the walk then the tag which
 154has the fewest commits different from the input committish will be
 155selected and output.  Here fewest commits different is defined as
 156the number of commits which would be shown by `git log tag..input`
 157will be the smallest number of commits possible.
 158
 159GIT
 160---
 161Part of the linkgit:git[1] suite