`+`, followed by the source ref <src>, followed
by a colon `:`, followed by the destination ref <dst>.
It is used to specify with what <src> object the <dst> ref
- in the remote repository is to be updated.
+ in the remote repository is to be updated. If not specified,
+ the behavior of the command is controlled by the `push.default`
+ configuration variable.
+
The <src> is often the name of the branch you would want to push, but
it can be any arbitrary "SHA-1 expression", such as `master~4` or
the local side, the remote side is updated if a branch of the same name
already exists on the remote side. This is the default operation mode
if no explicit refspec is found (that is neither on the command line
-nor in any Push line of the corresponding remotes file---see below).
+nor in any Push line of the corresponding remotes file---see below) and
+no `push.default` configuration variable is set.
--all::
Instead of naming each ref to push, specifies that all
`git push origin :`.
+
The default behavior of this command when no <refspec> is given can be
-configured by setting the `push` option of the remote.
+configured by setting the `push` option of the remote, or the `push.default`
+configuration variable.
+
For example, to default to pushing only the current branch to `origin`
use `git config remote.origin.push HEAD`. Any valid <refspec> (like