update
------
-This hook is invoked by `git-receive-pack`, which is invoked
-when a `git push` is done against the repository. It takes
-three parameters, name of the ref being updated, old object name
-stored in the ref, and the new objectname to be stored in the
-ref. Exiting with non-zero status from this hook prevents
-`git-receive-pack` from updating the ref.
-
-This can be used to prevent 'forced' update on certain refs by
+This hook is invoked by `git-receive-pack` on the remote repository,
+which is happens when a `git push` is done on a local repository.
+Just before updating the ref on the remote repository, the update hook
+is invoked. Its exit status determines the success or failure of
+the ref update.
+
+The hook executes once for each ref to be updated, and takes
+three parameters:
+ - the name of the ref being updated,
+ - the old object name stored in the ref,
+ - and the new objectname to be stored in the ref.
+
+A zero exit from the update hook allows the ref to be updated.
+Exiting with a non-zero status prevents `git-receive-pack`
+from updating the ref.
+
+This hook can be used to prevent 'forced' update on certain refs by
making sure that the object name is a commit object that is a
descendant of the commit object named by the old object name.
+That is, to enforce a "fast forward only" policy.
+
+It could also be used to log the old..new status. However, it
+does not know the entire set of branches, so it would end up
+firing one e-mail per ref when used naively, though.
+
Another use suggested on the mailing list is to use this hook to
implement access control which is finer grained than the one
based on filesystem group.
want to report something to the git-send-pack on the other end,
you can redirect your output to your stderr.
+
post-update
-----------
-This hook is invoked by `git-receive-pack`, which is invoked
-when a `git push` is done against the repository. It takes
-variable number of parameters; each of which is the name of ref
-that was actually updated.
+This hook is invoked by `git-receive-pack` on the remote repository,
+which is happens when a `git push` is done on a local repository.
+It executes on the remote repository once after all the refs have
+been updated.
+
+It takes a variable number of parameters, each of which is the
+name of ref that was actually updated.
This hook is meant primarily for notification, and cannot affect
the outcome of `git-receive-pack`.
+The post-update hook can tell what are the heads that were pushed,
+but it does not know what their original and updated values are,
+so it is a poor place to do log old..new.
+
The default post-update hook, when enabled, runs
`git-update-server-info` to keep the information used by dumb
-transport up-to-date.
+transports (e.g., http) up-to-date. If you are publishing
+a git repository that is accessible via http, you should
+probably enable this hook.
The standard output of this hook is sent to /dev/null; if you
want to report something to the git-send-pack on the other end,