GIT-CHECK-REF-FORMAT(1)

💅 git-check-ref-format — bestie's guide to well-formed refs

okay so real talk: this is from the Git Manual (git-check-ref-format(1)), and it's literally the vibe-check page for reference names. Let's get into it 💖

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✨ NAME ✨

git-check-ref-format — bestie, it makes sure a reference name is well formed. that's the whole job. and she does it flawlessly. 👑

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🎀 SYNOPSIS 🎀

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

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🌸 DESCRIPTION 🌸

So what she does is: she checks if a given <refname> is acceptable, and exits with a non-zero status if it's not. i.e. if it's ugly, she says no. 😤

A reference is what Git uses to specify branches and tags. A branch head lives in the refs/heads hierarchy, and a tag lives in the refs/tags hierarchy of the ref namespace — typically in the $GIT_DIR/refs/heads and $GIT_DIR/refs/tags directories, or, if your refs got packed by git gc, as entries in the file $GIT_DIR/packed-refs. slay, storage options. 🗂️

Git imposes the following rules on how references are named (and honestly? they're giving strict but fair):

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. (waived!! she's flexible 💅)
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 \.

🦋 why are we like this 🦋

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

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.

💜 the --branch situation 💜

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. so like, don't assume they're the same check, bestie.

When run with the --branch option in a repository, the input is first expanded for the "previous checkout syntax" @{-n}. For example, @{-1} is a way to refer to 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. plot twist 😭

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🔥 OPTIONS 🔥

• --allow-onelevel, --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*). one star. that's the limit. 💀
• --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.) 🫶

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🌈 EXAMPLES 🌈

• Print the name of the previous thing checked out:

$ 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 ; }

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⭐ GIT ⭐

Part of the git(1) suite. 💖 one big happy family fr fr.

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and that's the page, bestie — she ate and left no crumbs 👑✨

signed off with love from Git 2.56.0, dated 2026-09-27 — version and date both iconic, no cap 🎀💅