Documentation / git-describe.txton commit pack-objects: ignore ambiguous object warnings (a4544b3)
   1git-describe(1)
   2===============
   3
   4NAME
   5----
   6git-describe - Give an object a human readable name based on an available ref
   7
   8SYNOPSIS
   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
  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
  27If the given object refers to a blob, it will be described
  28as `<commit-ish>:<path>`, such that the blob can be found
  29at `<path>` in the `<commit-ish>`, which itself describes the
  30first commit in which this blob occurs in a reverse revision walk
  31from HEAD.
  32
  33OPTIONS
  34-------
  35<commit-ish>...::
  36        Commit-ish object names to describe.  Defaults to HEAD if omitted.
  37
  38--dirty[=<mark>]::
  39--broken[=<mark>]::
  40        Describe the state of the working tree.  When the working
  41        tree matches HEAD, the output is the same as "git describe
  42        HEAD".  If the working tree has local modification "-dirty"
  43        is appended to it.  If a repository is corrupt and Git
  44        cannot determine if there is local modification, Git will
  45        error out, unless `--broken' is given, which appends
  46        the suffix "-broken" instead.
  47
  48--all::
  49        Instead of using only the annotated tags, use any ref
  50        found in `refs/` namespace.  This option enables matching
  51        any known branch, remote-tracking branch, or lightweight tag.
  52
  53--tags::
  54        Instead of using only the annotated tags, use any tag
  55        found in `refs/tags` namespace.  This option enables matching
  56        a lightweight (non-annotated) tag.
  57
  58--contains::
  59        Instead of finding the tag that predates the commit, find
  60        the tag that comes after the commit, and thus contains it.
  61        Automatically implies --tags.
  62
  63--abbrev=<n>::
  64        Instead of using the default 7 hexadecimal digits as the
  65        abbreviated object name, use <n> digits, or as many digits
  66        as needed to form a unique object name.  An <n> of 0
  67        will suppress long format, only showing the closest tag.
  68
  69--candidates=<n>::
  70        Instead of considering only the 10 most recent tags as
  71        candidates to describe the input commit-ish consider
  72        up to <n> candidates.  Increasing <n> above 10 will take
  73        slightly longer but may produce a more accurate result.
  74        An <n> of 0 will cause only exact matches to be output.
  75
  76--exact-match::
  77        Only output exact matches (a tag directly references the
  78        supplied commit).  This is a synonym for --candidates=0.
  79
  80--debug::
  81        Verbosely display information about the searching strategy
  82        being employed to standard error.  The tag name will still
  83        be printed to standard out.
  84
  85--long::
  86        Always output the long format (the tag, the number of commits
  87        and the abbreviated commit name) even when it matches a tag.
  88        This is useful when you want to see parts of the commit object name
  89        in "describe" output, even when the commit in question happens to be
  90        a tagged version.  Instead of just emitting the tag name, it will
  91        describe such a commit as v1.2-0-gdeadbee (0th commit since tag v1.2
  92        that points at object deadbee....).
  93
  94--match <pattern>::
  95        Only consider tags matching the given `glob(7)` pattern,
  96        excluding the "refs/tags/" prefix. If used with `--all`, it also
  97        considers local branches and remote-tracking references matching the
  98        pattern, excluding respectively "refs/heads/" and "refs/remotes/"
  99        prefix; references of other types are never considered. If given
 100        multiple times, a list of patterns will be accumulated, and tags
 101        matching any of the patterns will be considered.  Use `--no-match` to
 102        clear and reset the list of patterns.
 103
 104--exclude <pattern>::
 105        Do not consider tags matching the given `glob(7)` pattern, excluding
 106        the "refs/tags/" prefix. If used with `--all`, it also does not consider
 107        local branches and remote-tracking references matching the pattern,
 108        excluding respectively "refs/heads/" and "refs/remotes/" prefix;
 109        references of other types are never considered. If given multiple times,
 110        a list of patterns will be accumulated and tags matching any of the
 111        patterns will be excluded. When combined with --match a tag will be
 112        considered when it matches at least one --match pattern and does not
 113        match any of the --exclude patterns. Use `--no-exclude` to clear and
 114        reset the list of patterns.
 115
 116--always::
 117        Show uniquely abbreviated commit object as fallback.
 118
 119--first-parent::
 120        Follow only the first parent commit upon seeing a merge commit.
 121        This is useful when you wish to not match tags on branches merged
 122        in the history of the target commit.
 123
 124EXAMPLES
 125--------
 126
 127With something like git.git current tree, I get:
 128
 129        [torvalds@g5 git]$ git describe parent
 130        v1.0.4-14-g2414721
 131
 132i.e. the current head of my "parent" branch is based on v1.0.4,
 133but since it has a few commits on top of that,
 134describe has added the number of additional commits ("14") and
 135an abbreviated object name for the commit itself ("2414721")
 136at the end.
 137
 138The number of additional commits is the number
 139of commits which would be displayed by "git log v1.0.4..parent".
 140The hash suffix is "-g" + 7-char abbreviation for the tip commit
 141of parent (which was `2414721b194453f058079d897d13c4e377f92dc6`).
 142The "g" prefix stands for "git" and is used to allow describing the version of
 143a software depending on the SCM the software is managed with. This is useful
 144in an environment where people may use different SCMs.
 145
 146Doing a 'git describe' on a tag-name will just show the tag name:
 147
 148        [torvalds@g5 git]$ git describe v1.0.4
 149        v1.0.4
 150
 151With --all, the command can use branch heads as references, so
 152the output shows the reference path as well:
 153
 154        [torvalds@g5 git]$ git describe --all --abbrev=4 v1.0.5^2
 155        tags/v1.0.0-21-g975b
 156
 157        [torvalds@g5 git]$ git describe --all --abbrev=4 HEAD^
 158        heads/lt/describe-7-g975b
 159
 160With --abbrev set to 0, the command can be used to find the
 161closest tagname without any suffix:
 162
 163        [torvalds@g5 git]$ git describe --abbrev=0 v1.0.5^2
 164        tags/v1.0.0
 165
 166Note that the suffix you get if you type these commands today may be
 167longer than what Linus saw above when he ran these commands, as your
 168Git repository may have new commits whose object names begin with
 169975b that did not exist back then, and "-g975b" suffix alone may not
 170be sufficient to disambiguate these commits.
 171
 172
 173SEARCH STRATEGY
 174---------------
 175
 176For each commit-ish supplied, 'git describe' will first look for
 177a tag which tags exactly that commit.  Annotated tags will always
 178be preferred over lightweight tags, and tags with newer dates will
 179always be preferred over tags with older dates.  If an exact match
 180is found, its name will be output and searching will stop.
 181
 182If an exact match was not found, 'git describe' will walk back
 183through the commit history to locate an ancestor commit which
 184has been tagged.  The ancestor's tag will be output along with an
 185abbreviation of the input commit-ish's SHA-1. If `--first-parent` was
 186specified then the walk will only consider the first parent of each
 187commit.
 188
 189If multiple tags were found during the walk then the tag which
 190has the fewest commits different from the input commit-ish will be
 191selected and output.  Here fewest commits different is defined as
 192the number of commits which would be shown by `git log tag..input`
 193will be the smallest number of commits possible.
 194
 195BUGS
 196----
 197
 198Tree objects as well as tag objects not pointing at commits, cannot be described.
 199When describing blobs, the lightweight tags pointing at blobs are ignored,
 200but the blob is still described as <committ-ish>:<path> despite the lightweight
 201tag being favorable.
 202
 203GIT
 204---
 205Part of the linkgit:git[1] suite