Man page 1 : git-check-ref-format

git-check-ref-format - Ensures that a reference name is well formed

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:


    .ie n \ \h'-04' 1.\h'+01'\c .

1. 4.2 . They can include slash / for hierarchical (directory) grouping, but no slash-separated component can begin with a dot ..


    .ie n \ \h'-04' 2.\h'+01'\c .

2. 4.2 . They must contain at least one /. This enforces the presence of a category like heads/, tags/ etc. but the actual names are not restricted.


    .ie n \ \h'-04' 3.\h'+01'\c .

3. 4.2 . They cannot have two consecutive dots .. anywhere.


    .ie n \ \h'-04' 4.\h'+01'\c .

4. 4.2 . They cannot have ASCII control characters (i.e. bytes whose values are lower than \040, or \177 DEL), space, tilde ~, caret ^, colon :, question-mark ?, asterisk *, or open bracket [ anywhere.


    .ie n \ \h'-04' 5.\h'+01'\c .

5. 4.2 . They cannot end with a slash / nor a dot ..


    .ie n \ \h'-04' 6.\h'+01'\c .

6. 4.2 . They cannot end with the sequence .lock.


    .ie n \ \h'-04' 7.\h'+01'\c .

7. 4.2 . They cannot contain a sequence @{.


    .ie n \ \h'-04' 8.\h'+01'\c .

8. 4.2 . 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(1)):


    .ie n \ \h'-04' 1.\h'+01'\c .

1. 4.2 . 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).


    .ie n \ \h'-04' 2.\h'+01'\c .

2. 4.2 . A tilde ~ and caret ^ are used to introduce the postfix nth parent and peel onion operation.


    .ie n \ \h'-04' 3.\h'+01'\c .

3. 4.2 . A colon : is used as in srcref:dstref to mean "use srcref(cqs 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".


    .ie n \ \h'-04' 4.\h'+01'\c .

4. 4.2 . 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.

    .ie n \ \h'-04'\h'+03'\c .

2.3 . Print the name of the previous branch:


    .

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

.




    .ie n \ \h'-04'\h'+03'\c .

2.3 . Determine the reference name to use for a new branch:


    .

$ ref=$(git check-ref-format --print "refs/heads/$newbranch") ||
die "we do not like \*(Aq$newbranch\*(Aq as a branch name."

.

Part of the git(1) suite