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' <refname>
  12 'git check-ref-format' --print <refname>
  13 'git check-ref-format' --branch <branchname-shorthand>
  14
  15 DESCRIPTION
  16 -----------
  17 Checks if a given 'refname' is acceptable, and exits with a non-zero
  18 status if it is not.
  19
  20 A reference is used in git to specify branches and tags.  A
  21 branch head is stored under the `$GIT_DIR/refs/heads` directory, and
  22 a tag is stored under the `$GIT_DIR/refs/tags` directory (or, if refs
  23 are packed by `git gc`, as entries in the `$GIT_DIR/packed-refs` file).
  24 git imposes the following rules on how references are named:
  25
  26 . They can include slash `/` for hierarchical (directory)
  27   grouping, but no slash-separated component can begin with a
  28   dot `.`.
  29
  30 . They must contain at least one `/`. This enforces the presence of a
  31   category like `heads/`, `tags/` etc. but the actual names are not
  32   restricted.
  33
  34 . They cannot have two consecutive dots `..` anywhere.
  35
  36 . They cannot have ASCII control characters (i.e. bytes whose
  37   values are lower than \040, or \177 `DEL`), space, tilde `~`,
  38   caret `{caret}`, colon `:`, question-mark `?`, asterisk `*`,
  39   or open bracket `[` anywhere.
  40
  41 . They cannot end with a slash `/` nor a dot `.`.
  42
  43 . They cannot end with the sequence `.lock`.
  44
  45 . They cannot contain a sequence `@{`.
  46
  47 . They cannot contain a `\`.
  48
  49 These rules make it easy for shell script based tools to parse
  50 reference names, pathname expansion by the shell when a reference name is used
  51 unquoted (by mistake), and also avoids ambiguities in certain
  52 reference name expressions (see linkgit:gitrevisions[7]):
  53
  54 . A double-dot `..` is often used as in `ref1..ref2`, and in some
  55   contexts this notation means `{caret}ref1 ref2` (i.e. not in
  56   `ref1` and in `ref2`).
  57
  58 . A tilde `~` and caret `{caret}` are used to introduce the postfix
  59   'nth parent' and 'peel onion' operation.
  60
  61 . A colon `:` is used as in `srcref:dstref` to mean "use srcref\'s
  62   value and store it in dstref" in fetch and push operations.
  63   It may also be used to select a specific object such as with
  64   'git cat-file': "git cat-file blob v1.3.3:refs.c".
  65
  66 . at-open-brace `@{` is used as a notation to access a reflog entry.
  67
  68 With the `--print` option, if 'refname' is acceptable, it prints the
  69 canonicalized name of a hypothetical reference with that name.  That is,
  70 it prints 'refname' with any extra `/` characters removed.
  71
  72 With the `--branch` option, it expands the ``previous branch syntax''
  73 `@{-n}`.  For example, `@{-1}` is a way to refer the last branch you
  74 were on.  This option should be used by porcelains to accept this
  75 syntax anywhere a branch name is expected, so they can act as if you
  76 typed the branch name.
  77
  78 EXAMPLES
  79 --------
  80
  81 * Print the name of the previous branch:
  82 +
  83 ------------
  84 $ git check-ref-format --branch @{-1}
  85 ------------
  86
  87 * Determine the reference name to use for a new branch:
  88 +
  89 ------------
  90 $ ref=$(git check-ref-format --print "refs/heads/$newbranch") ||
  91 die "we do not like '$newbranch' as a branch name."
  92 ------------
  93
  94 GIT
  95 ---
  96 Part of the linkgit:git[1] suite