Merge branch 'master' into lj/refs
[git/git.git] / Documentation / hooks.txt
1 Hooks used by git
2 =================
3
4 Hooks are little scripts you can place in `$GIT_DIR/hooks`
5 directory to trigger action at certain points. When
6 `git-init-db` is run, a handful example hooks are copied in the
7 `hooks` directory of the new repository, but by default they are
8 all disabled. To enable a hook, make it executable with `chmod +x`.
9
10 This document describes the currently defined hooks.
11
12 applypatch-msg
13 --------------
14
15 This hook is invoked by `git-applypatch` script, which is
16 typically invoked by `git-applymbox`. It takes a single
17 parameter, the name of the file that holds the proposed commit
18 log message. Exiting with non-zero status causes
19 `git-applypatch` to abort before applying the patch.
20
21 The hook is allowed to edit the message file in place, and can
22 be used to normalize the message into some project standard
23 format (if the project has one). It can also be used to refuse
24 the commit after inspecting the message file.
25
26 The default 'applypatch-msg' hook, when enabled, runs the
27 'commit-msg' hook, if the latter is enabled.
28
29 pre-applypatch
30 --------------
31
32 This hook is invoked by `git-applypatch` script, which is
33 typically invoked by `git-applymbox`. It takes no parameter,
34 and is invoked after the patch is applied, but before a commit
35 is made. Exiting with non-zero status causes the working tree
36 after application of the patch not committed.
37
38 It can be used to inspect the current working tree and refuse to
39 make a commit if it does not pass certain test.
40
41 The default 'pre-applypatch' hook, when enabled, runs the
42 'pre-commit' hook, if the latter is enabled.
43
44 post-applypatch
45 ---------------
46
47 This hook is invoked by `git-applypatch` script, which is
48 typically invoked by `git-applymbox`. It takes no parameter,
49 and is invoked after the patch is applied and a commit is made.
50
51 This hook is meant primarily for notification, and cannot affect
52 the outcome of `git-applypatch`.
53
54 pre-commit
55 ----------
56
57 This hook is invoked by `git-commit`, and can be bypassed
58 with `\--no-verify` option. It takes no parameter, and is
59 invoked before obtaining the proposed commit log message and
60 making a commit. Exiting with non-zero status from this script
61 causes the `git-commit` to abort.
62
63 The default 'pre-commit' hook, when enabled, catches introduction
64 of lines with trailing whitespaces and aborts the commit when
65 such a line is found.
66
67 commit-msg
68 ----------
69
70 This hook is invoked by `git-commit`, and can be bypassed
71 with `\--no-verify` option. It takes a single parameter, the
72 name of the file that holds the proposed commit log message.
73 Exiting with non-zero status causes the `git-commit` to
74 abort.
75
76 The hook is allowed to edit the message file in place, and can
77 be used to normalize the message into some project standard
78 format (if the project has one). It can also be used to refuse
79 the commit after inspecting the message file.
80
81 The default 'commit-msg' hook, when enabled, detects duplicate
82 "Signed-off-by" lines, and aborts the commit if one is found.
83
84 post-commit
85 -----------
86
87 This hook is invoked by `git-commit`. It takes no
88 parameter, and is invoked after a commit is made.
89
90 This hook is meant primarily for notification, and cannot affect
91 the outcome of `git-commit`.
92
93 The default 'post-commit' hook, when enabled, demonstrates how to
94 send out a commit notification e-mail.
95
96 update
97 ------
98
99 This hook is invoked by `git-receive-pack` on the remote repository,
100 which happens when a `git push` is done on a local repository.
101 Just before updating the ref on the remote repository, the update hook
102 is invoked. Its exit status determines the success or failure of
103 the ref update.
104
105 The hook executes once for each ref to be updated, and takes
106 three parameters:
107
108 - the name of the ref being updated,
109 - the old object name stored in the ref,
110 - and the new objectname to be stored in the ref.
111
112 A zero exit from the update hook allows the ref to be updated.
113 Exiting with a non-zero status prevents `git-receive-pack`
114 from updating the ref.
115
116 This hook can be used to prevent 'forced' update on certain refs by
117 making sure that the object name is a commit object that is a
118 descendant of the commit object named by the old object name.
119 That is, to enforce a "fast forward only" policy.
120
121 It could also be used to log the old..new status. However, it
122 does not know the entire set of branches, so it would end up
123 firing one e-mail per ref when used naively, though.
124
125 Another use suggested on the mailing list is to use this hook to
126 implement access control which is finer grained than the one
127 based on filesystem group.
128
129 The standard output of this hook is sent to `/dev/null`; if you
130 want to report something to the `git-send-pack` on the other end,
131 you can redirect your output to your `stderr`.
132
133
134 post-update
135 -----------
136
137 This hook is invoked by `git-receive-pack` on the remote repository,
138 which happens when a `git push` is done on a local repository.
139 It executes on the remote repository once after all the refs have
140 been updated.
141
142 It takes a variable number of parameters, each of which is the
143 name of ref that was actually updated.
144
145 This hook is meant primarily for notification, and cannot affect
146 the outcome of `git-receive-pack`.
147
148 The 'post-update' hook can tell what are the heads that were pushed,
149 but it does not know what their original and updated values are,
150 so it is a poor place to do log old..new.
151
152 When enabled, the default 'post-update' hook runs
153 `git-update-server-info` to keep the information used by dumb
154 transports (e.g., HTTP) up-to-date. If you are publishing
155 a git repository that is accessible via HTTP, you should
156 probably enable this hook.
157
158 The standard output of this hook is sent to `/dev/null`; if you
159 want to report something to the `git-send-pack` on the other end,
160 you can redirect your output to your `stderr`.