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 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 avoids 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 place of a one full
  pathname component (e.g., foo/*/bar but not foo/bar*).
--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") ||
die "we do not like '$newbranch' as a branch name."