Git push --all vs --mirror

Question

What is the difference between git push --all and git push --mirror?

I only know this:

• With deleted local branch, --all doesn't push it and --mirror does.

This is correct?

Any other differences?

Answer 1

As it says in the documentation:

--all

Push all branches (i.e. refs under refs/heads/); cannot be used with other <refspec>.

--mirror

... specifies that all refs under refs/ (which includes but is not limited to refs/heads/, refs/remotes/, and refs/tags/) be mirrored ...

So a, if not the, key difference is that one means refs/heads/* and one means refs/*. The refs/heads/* names are the branch names. Anything in refs/remotes/ is a remote-tracking name, and anything in refs/tags/ is a tag name. Other notable name-spaces include refs/notes/, refs/replace/, and the singular refs/stash.

The --mirror option goes on to mention:

locally updated refs will be force updated on the remote end, and deleted refs will be removed from the remote end.

Hence --mirror effectively implies both --force and --prune; --all does not. You can, however, add --force and/or --prune to git push --all, if you like.

It is always up to the other Git to decide whether to obey polite requests (those sent without --force) or commands (--force) to make changes to its references.

With deleted local branch, --all doesn't push it and --mirror does.

This is a consequence of the --prune option: telling your Git to use --prune means "ask them to delete names in their name-space(s) that are not in mine".