Documentation / git-describe.txton commit gitweb: Add a few comments about %feature hash (b4b20b2)
   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'git-describe' [--all] [--tags] [--abbrev=<n>] <committish>...
  12
  13DESCRIPTION
  14-----------
  15The command finds the most recent tag that is reachable from a
  16commit, and if the commit itself is pointed at by the tag, shows
  17the tag.  Otherwise, it suffixes the tag name with the number of
  18additional commits and the abbreviated object name of the commit.
  19
  20
  21OPTIONS
  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
  49EXAMPLES
  50--------
  51
  52With something like git.git current tree, I get:
  53
  54        [torvalds@g5 git]$ git-describe parent
  55        v1.0.4-14-g2414721
  56
  57i.e. the current head of my "parent" branch is based on v1.0.4,
  58but since it has a handful commits on top of that,
  59describe has added the number of additional commits ("14") and
  60an abbreviated object name for the commit itself ("2414721")
  61at the end.
  62
  63The number of additional commits is the number
  64of commits which would be displayed by "git log v1.0.4..parent".
  65The hash suffix is "-g" + 7-char abbreviation for the tip commit
  66of parent (which was `2414721b194453f058079d897d13c4e377f92dc6`).
  67
  68Doing 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
  73With --all, the command can use branch heads as references, so
  74the 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
  82With --abbrev set to 0, the command can be used to find the
  83closest tagname without any suffix:
  84
  85        [torvalds@g5 git]$ git describe --abbrev=0 v1.0.5^2
  86        tags/v1.0.0
  87
  88SEARCH STRATEGY
  89---------------
  90
  91For each committish supplied "git describe" will first look for
  92a tag which tags exactly that commit.  Annotated tags will always
  93be preferred over lightweight tags, and tags with newer dates will
  94always be preferred over tags with older dates.  If an exact match
  95is found, its name will be output and searching will stop.
  96
  97If an exact match was not found "git describe" will walk back
  98through the commit history to locate an ancestor commit which
  99has been tagged.  The ancestor's tag will be output along with an
 100abbreviation of the input committish's SHA1.
 101
 102If multiple tags were found during the walk then the tag which
 103has the fewest commits different from the input committish will be
 104selected and output.  Here fewest commits different is defined as
 105the number of commits which would be shown by "git log tag..input"
 106will be the smallest number of commits possible.
 107
 108
 109Author
 110------
 111Written by Linus Torvalds <torvalds@osdl.org>, but somewhat
 112butchered by Junio C Hamano <junkio@cox.net>.  Later significantly
 113updated by Shawn Pearce <spearce@spearce.org>.
 114
 115Documentation
 116--------------
 117Documentation by David Greaves, Junio C Hamano and the git-list <git@vger.kernel.org>.
 118
 119GIT
 120---
 121Part of the gitlink:git[7] suite
 122