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GIT-CHECK-REF-FORMAT(1) Git Manual 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, 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 2.41.0 2023-06-01 GIT-CHECK-REF-FORMAT(1)