Documentation/git-check-ref-format.txt

   1 git-check-ref-format(1)
   2 =======================
   3
   4 NAME
   5 ----
   6 git-check-ref-format - Ensures that a reference name is well formed
   7
   8 SYNOPSIS
   9 --------
  10 [verse]
  11 'git check-ref-format' [--normalize]
  12        [--[no-]allow-onelevel] [--refspec-pattern]
  13        <refname>
  14 'git check-ref-format' --branch <branchname-shorthand>
  15
  16 DESCRIPTION
  17 -----------
  18 Checks if a given 'refname' is acceptable, and exits with a non-zero
  19 status if it is not.
  20
  21 A reference is used in Git to specify branches and tags.  A
  22 branch head is stored in the `refs/heads` hierarchy, while
  23 a tag is stored in the `refs/tags` hierarchy of the ref namespace
  24 (typically in `$GIT_DIR/refs/heads` and `$GIT_DIR/refs/tags`
  25 directories or, as entries in file `$GIT_DIR/packed-refs`
  26 if refs are packed by `git gc`).
  27
  28 Git imposes the following rules on how references are named:
  29
  30 . They can include slash `/` for hierarchical (directory)
  31   grouping, but no slash-separated component can begin with a
  32   dot `.` or end with the sequence `.lock`.
  33
  34 . They must contain at least one `/`. This enforces the presence of a
  35   category like `heads/`, `tags/` etc. but the actual names are not
  36   restricted.  If the `--allow-onelevel` option is used, this rule
  37   is waived.
  38
  39 . They cannot have two consecutive dots `..` anywhere.
  40
  41 . They cannot have ASCII control characters (i.e. bytes whose
  42   values are lower than \040, or \177 `DEL`), space, tilde `~`,
  43   caret `^`, or colon `:` anywhere.
  44
  45 . They cannot have question-mark `?`, asterisk `*`, or open
  46   bracket `[` anywhere.  See the `--refspec-pattern` option below for
  47   an exception to this rule.
  48
  49 . They cannot begin or end with a slash `/` or contain multiple
  50   consecutive slashes (see the `--normalize` option below for an
  51   exception to this rule)
  52
  53 . They cannot end with a dot `.`.
  54
  55 . They cannot contain a sequence `@{`.
  56
  57 . They cannot be the single character `@`.
  58
  59 . They cannot contain a `\`.
  60
  61 These rules make it easy for shell script based tools to parse
  62 reference names, pathname expansion by the shell when a reference name is used
  63 unquoted (by mistake), and also avoid ambiguities in certain
  64 reference name expressions (see linkgit:gitrevisions[7]):
  65
  66 . A double-dot `..` is often used as in `ref1..ref2`, and in some
  67   contexts this notation means `^ref1 ref2` (i.e. not in
  68   `ref1` and in `ref2`).
  69
  70 . A tilde `~` and caret `^` are used to introduce the postfix
  71   'nth parent' and 'peel onion' operation.
  72
  73 . A colon `:` is used as in `srcref:dstref` to mean "use srcref\'s
  74   value and store it in dstref" in fetch and push operations.
  75   It may also be used to select a specific object such as with
  76   'git cat-file': "git cat-file blob v1.3.3:refs.c".
  77
  78 . at-open-brace `@{` is used as a notation to access a reflog entry.
  79
  80 With the `--branch` option, the command takes a name and checks if
  81 it can be used as a valid branch name (e.g. when creating a new
  82 branch). But be cautious when using the
  83 previous checkout syntax that may refer to a detached HEAD state.
  84 The rule `git check-ref-format --branch $name` implements
  85 may be stricter than what `git check-ref-format refs/heads/$name`
  86 says (e.g. a dash may appear at the beginning of a ref component,
  87 but it is explicitly forbidden at the beginning of a branch name).
  88 When run with `--branch` option in a repository, the input is first
  89 expanded for the ``previous checkout syntax''
  90 `@{-n}`.  For example, `@{-1}` is a way to refer the last thing that
  91 was checked out using "git checkout" operation. This option should be
  92 used by porcelains to accept this syntax anywhere a branch name is
  93 expected, so they can act as if you typed the branch name. As an
  94 exception note that, the ``previous checkout operation'' might result
  95 in a commit object name when the N-th last thing checked out was not
  96 a branch.
  97
  98 OPTIONS
  99 -------
 100 --[no-]allow-onelevel::
 101         Controls whether one-level refnames are accepted (i.e.,
 102         refnames that do not contain multiple `/`-separated
 103         components).  The default is `--no-allow-onelevel`.
 104
 105 --refspec-pattern::
 106         Interpret <refname> as a reference name pattern for a refspec
 107         (as used with remote repositories).  If this option is
 108         enabled, <refname> is allowed to contain a single `*`
 109         in the refspec (e.g., `foo/bar*/baz` or `foo/bar*baz/`
 110         but not `foo/bar*/baz*`).
 111
 112 --normalize::
 113         Normalize 'refname' by removing any leading slash (`/`)
 114         characters and collapsing runs of adjacent slashes between
 115         name components into a single slash.  If the normalized
 116         refname is valid then print it to standard output and exit
 117         with a status of 0, otherwise exit with a non-zero status.
 118         (`--print` is a deprecated way to spell `--normalize`.)
 119
 120
 121 EXAMPLES
 122 --------
 123
 124 * Print the name of the previous thing checked out:
 125 +
 126 ------------
 127 $ git check-ref-format --branch @{-1}
 128 ------------
 129
 130 * Determine the reference name to use for a new branch:
 131 +
 132 ------------
 133 $ ref=$(git check-ref-format --normalize "refs/heads/$newbranch")||
 134 { echo "we do not like '$newbranch' as a branch name." >&2 ; exit 1 ; }
 135 ------------
 136
 137 GIT
 138 ---
 139 Part of the linkgit:git[1] suite