git-mktag - Creates a tag object with extra validation

Reads a tag contents on standard input and creates a tag object. The output is the new tag’s <object> identifier.

This command is mostly equivalent to git-hash-object[1] invoked with -t tag -w --stdin. I.e. both of these will create and write a tag found in my-tag:

git mktag <my-tag
git hash-object -t tag -w --stdin <my-tag

The difference is that mktag will die before writing the tag if the tag doesn’t pass a git-fsck[1] check.

The "fsck" check done mktag is stricter than what git-fsck[1] would run by default in that all fsck.<msg-id> messages are promoted from warnings to errors (so e.g. a missing "tagger" line is an error).

Extra headers in the object are also an error under mktag, but ignored by git-fsck[1]. This extra check can be turned off by setting the appropriate fsck.<msg-id> variable:

git -c fsck.extraHeaderEntry=ignore mktag <my-tag-with-headers

A tag signature file, to be fed to this command’s standard input, has a very simple fixed format: four lines of

object <hash>
type <typename>
tag <tagname>
tagger <tagger>

followed by some optional free-form message (some tags created by older Git may not have tagger line). The message, when it exists, is separated by a blank line from the header. The message part may contain a signature that Git itself doesn’t care about, but that can be verified with gpg.