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git-check-ref-format - Ensures that a reference name is well formed
'git check-ref-format' <refname>
'git check-ref-format' --print <refname>
'git check-ref-format' --branch <branchname-shorthand>
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 under the `$GIT_DIR/refs/heads` directory, and
a tag is stored under the `$GIT_DIR/refs/tags` directory (or, if refs
are packed by `git gc`, as entries in the `$GIT_DIR/packed-refs` file).
git imposes the following rules on how references are named:
. They can include slash `/` for hierarchical (directory)
grouping, but no slash-separated component can begin with a
dot `.`.
. They must contain at least one `/`. This enforces the presence of a
category like `heads/`, `tags/` etc. but the actual names are not
. They cannot have two consecutive dots `..` anywhere.
. They cannot have ASCII control characters (i.e. bytes whose
values are lower than \040, or \177 `DEL`), space, tilde `~`,
caret `{caret}`, colon `:`, question-mark `?`, asterisk `*`,
or open bracket `[` anywhere.
. They cannot end with a slash `/` nor a dot `.`.
. They cannot end with the sequence `.lock`.
. They cannot contain a sequence `@{`.
. 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 linkgit:gitrevisions[7]):
. A double-dot `..` is often used as in `ref1..ref2`, and in some
contexts this notation means `{caret}ref1 ref2` (i.e. not in
`ref1` and in `ref2`).
. A tilde `~` and caret `{caret}` are used to introduce the postfix
'nth parent' and 'peel onion' operation.
. 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".
. at-open-brace `@{` is used as a notation to access a reflog entry.
With the `--print` option, if 'refname' is acceptable, it prints the
canonicalized name of a hypothetical reference with that name. That is,
it prints 'refname' with any extra `/` characters removed.
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.
* Print the name of the previous branch:
$ git check-ref-format --branch @{-1}
* Determine the reference name to use for a new branch:
$ ref=$(git check-ref-format --print "refs/heads/$newbranch") ||
die "we do not like '$newbranch' as a branch name."
Part of the linkgit:git[1] suite