git-check-ref-format

GIT-CHECK-REF-FOR(1)              Git Manual              GIT-CHECK-REF-FOR(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, the command takes a name and checks if it can
       be used as a valid branch name (e.g. when creating a new branch). But
       be cautious when using the previous checkout syntax that may refer to a
       detached HEAD state. The rule git check-ref-format --branch $name
       implements may be stricter than what git check-ref-format
       refs/heads/$name says (e.g. a dash may appear at the beginning of a ref
       component, but it is explicitly forbidden at the beginning of a branch
       name). When run with --branch option in a repository, the input is
       first expanded for the "previous checkout syntax" @{-n}. For example,
       @{-1} is a way to refer the last thing that was checked out using "git
       switch" or "git checkout" operation. 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. As an exception note
       that, the "previous checkout operation" might result in a commit object
       name when the N-th last thing checked out was not a branch.

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. If the normalized refname is valid then print it to
           standard output and exit with a status of 0, otherwise exit with a
           non-zero status. (--print is a deprecated way to spell
           --normalize.)

EXAMPLES
       o   Print the name of the previous thing checked out:

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

       o   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

Git 2.25.1                        04/26/2023              GIT-CHECK-REF-FOR(1)