git-check-ref-format(1)

NAME

   git-check-ref-format - Ensures that a reference name is well formed

SYNOPSIS

   git check-ref-format [--normalize]
          [--[no-]allow-onelevel] [--refspec-pattern]
          <refname>
   git check-ref-format --branch <branchname-shorthand>

DESCRIPTION

   Checks if a given refname is acceptable, and exits with a non-zero
   status if it is not.

   A reference is used in Git to specify branches and tags. A branch head
   is stored in the refs/heads hierarchy, while a tag is stored in the
   refs/tags hierarchy of the ref namespace (typically in
   $GIT_DIR/refs/heads and $GIT_DIR/refs/tags directories or, as entries
   in file $GIT_DIR/packed-refs if refs are packed by git gc).

   Git imposes the following rules on how references are named:

    1. They can include slash / for hierarchical (directory) grouping, but
       no slash-separated component can begin with a dot .  or end with
       the sequence .lock.

    2. They must contain at least one /. This enforces the presence of a
       category like heads/, tags/ etc. but the actual names are not
       restricted. If the --allow-onelevel option is used, this rule is
       waived.

    3. They cannot have two consecutive dots ..  anywhere.

    4. They cannot have ASCII control characters (i.e. bytes whose values
       are lower than \040, or \177 DEL), space, tilde ~, caret ^, or
       colon : anywhere.

    5. They cannot have question-mark ?, asterisk *, or open bracket [
       anywhere. See the --refspec-pattern option below for an exception
       to this rule.

    6. They cannot begin or end with a slash / or contain multiple
       consecutive slashes (see the --normalize option below for an
       exception to this rule)

    7. They cannot end with a dot ..

    8. They cannot contain a sequence @{.

    9. They cannot be the single character @.

   10. They cannot contain a \.

   These rules make it easy for shell script based tools to parse
   reference names, pathname expansion by the shell when a reference name
   is used unquoted (by mistake), and also avoid ambiguities in certain
   reference name expressions (see gitrevisions(7)):

    1. A double-dot ..  is often used as in ref1..ref2, and in some
       contexts this notation means ^ref1 ref2 (i.e. not in ref1 and in
       ref2).

    2. A tilde ~ and caret ^ are used to introduce the postfix nth parent
       and peel onion operation.

    3. A colon : is used as in srcref:dstref to mean "use srcref's value
       and store it in dstref" in fetch and push operations. It may also
       be used to select a specific object such as with git cat-file: "git
       cat-file blob v1.3.3:refs.c".

    4. at-open-brace @{ is used as a notation to access a reflog entry.

   With the --branch option, it expands the "previous branch syntax"
   @{-n}. For example, @{-1} is a way to refer the last branch you were
   on. This option should be used by porcelains to accept this syntax
   anywhere a branch name is expected, so they can act as if you typed the
   branch name.

OPTIONS

   --[no-]allow-onelevel
       Controls whether one-level refnames are accepted (i.e., refnames
       that do not contain multiple /-separated components). The default
       is --no-allow-onelevel.

   --refspec-pattern
       Interpret <refname> as a reference name pattern for a refspec (as
       used with remote repositories). If this option is enabled,
       <refname> is allowed to contain a single * in the refspec (e.g.,
       foo/bar*/baz or foo/bar*baz/ but not foo/bar*/baz*).

   --normalize
       Normalize refname by removing any leading slash (/) characters and
       collapsing runs of adjacent slashes between name components into a
       single slash. Iff the normalized refname is valid then print it to
       standard output and exit with a status of 0. (--print is a
       deprecated way to spell --normalize.)

EXAMPLES

   *   Print the name of the previous branch:

           $ git check-ref-format --branch @{-1}

   *   Determine the reference name to use for a new branch:

           $ ref=$(git check-ref-format --normalize "refs/heads/$newbranch")||
           { echo "we do not like '$newbranch' as a branch name." >&2 ; exit 1 ; }

GIT

   Part of the git(1) suite

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