Hooks are little scripts you can place in `$GIT_DIR/hooks`
directory to trigger action at certain points. When
-`git-init-db` is run, a handful example hooks are copied in the
+`git-init` is run, a handful example hooks are copied in the
`hooks` directory of the new repository, but by default they are
-all disabled. To enable a hook, make it executable with `chmod
-+x`.
+all disabled. To enable a hook, make it executable with `chmod +x`.
This document describes the currently defined hooks.
This hook is invoked by `git-applypatch` script, which is
typically invoked by `git-applymbox`. It takes a single
parameter, the name of the file that holds the proposed commit
-log message. Exiting with non-zero status causes the
-'git-applypatch' to abort before applying the patch.
+log message. Exiting with non-zero status causes
+`git-applypatch` to abort before applying the patch.
The hook is allowed to edit the message file in place, and can
be used to normalize the message into some project standard
format (if the project has one). It can also be used to refuse
the commit after inspecting the message file.
-The default applypatch-msg hook, when enabled, runs the
-commit-msg hook, if the latter is enabled.
+The default 'applypatch-msg' hook, when enabled, runs the
+'commit-msg' hook, if the latter is enabled.
pre-applypatch
--------------
It can be used to inspect the current working tree and refuse to
make a commit if it does not pass certain test.
-The default pre-applypatch hook, when enabled, runs the
-pre-commit hook, if the latter is enabled.
+The default 'pre-applypatch' hook, when enabled, runs the
+'pre-commit' hook, if the latter is enabled.
post-applypatch
---------------
making a commit. Exiting with non-zero status from this script
causes the `git-commit` to abort.
-The default pre-commit hook, when enabled, catches introduction
+The default 'pre-commit' hook, when enabled, catches introduction
of lines with trailing whitespaces and aborts the commit when
-a such line is found.
+such a line is found.
commit-msg
----------
format (if the project has one). It can also be used to refuse
the commit after inspecting the message file.
-The default commit-msg hook, when enabled, detects duplicate
-Signed-off-by: lines, and aborts the commit when one is found.
+The default 'commit-msg' hook, when enabled, detects duplicate
+"Signed-off-by" lines, and aborts the commit if one is found.
post-commit
-----------
This hook is meant primarily for notification, and cannot affect
the outcome of `git-commit`.
-The default post-commit hook, when enabled, demonstrates how to
+The default 'post-commit' hook, when enabled, demonstrates how to
send out a commit notification e-mail.
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 hook is invoked by `git-receive-pack` on the remote repository,
+which 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.
-This can be used to prevent 'forced' update on certain refs by
+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.
-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,
-you can redirect your output to your stderr.
+The standard output of this hook is sent to `stderr`, so if you
+want to report something to the `git-send-pack` on the other end,
+you can simply `echo` your messages.
+
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 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 default post-update hook, when enabled, runs
+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.
+
+When enabled, the default 'post-update' hook 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,
-you can redirect your output to your stderr.
+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,
+you can redirect your output to your `stderr`.