1Hooks used by git 2================= 3 4Hooks are little scripts you can place in `$GIT_DIR/hooks` 5directory to trigger action at certain points. When 6`git-init` is run, a handful example hooks are copied in the 7`hooks` directory of the new repository, but by default they are 8all disabled. To enable a hook, make it executable with `chmod +x`. 9 10This document describes the currently defined hooks. 11 12applypatch-msg 13-------------- 14 15This hook is invoked by `git-am` script. It takes a single 16parameter, the name of the file that holds the proposed commit 17log message. Exiting with non-zero status causes 18`git-am` to abort before applying the patch. 19 20The hook is allowed to edit the message file in place, and can 21be used to normalize the message into some project standard 22format (if the project has one). It can also be used to refuse 23the commit after inspecting the message file. 24 25The default 'applypatch-msg' hook, when enabled, runs the 26'commit-msg' hook, if the latter is enabled. 27 28pre-applypatch 29-------------- 30 31This hook is invoked by `git-am`. It takes no parameter, 32and is invoked after the patch is applied, but before a commit 33is made. Exiting with non-zero status causes the working tree 34after application of the patch not committed. 35 36It can be used to inspect the current working tree and refuse to 37make a commit if it does not pass certain test. 38 39The default 'pre-applypatch' hook, when enabled, runs the 40'pre-commit' hook, if the latter is enabled. 41 42post-applypatch 43--------------- 44 45This hook is invoked by `git-am`. It takes no parameter, 46and is invoked after the patch is applied and a commit is made. 47 48This hook is meant primarily for notification, and cannot affect 49the outcome of `git-am`. 50 51pre-commit 52---------- 53 54This hook is invoked by `git-commit`, and can be bypassed 55with `\--no-verify` option. It takes no parameter, and is 56invoked before obtaining the proposed commit log message and 57making a commit. Exiting with non-zero status from this script 58causes the `git-commit` to abort. 59 60The default 'pre-commit' hook, when enabled, catches introduction 61of lines with trailing whitespaces and aborts the commit when 62such a line is found. 63 64commit-msg 65---------- 66 67This hook is invoked by `git-commit`, and can be bypassed 68with `\--no-verify` option. It takes a single parameter, the 69name of the file that holds the proposed commit log message. 70Exiting with non-zero status causes the `git-commit` to 71abort. 72 73The hook is allowed to edit the message file in place, and can 74be used to normalize the message into some project standard 75format (if the project has one). It can also be used to refuse 76the commit after inspecting the message file. 77 78The default 'commit-msg' hook, when enabled, detects duplicate 79"Signed-off-by" lines, and aborts the commit if one is found. 80 81post-commit 82----------- 83 84This hook is invoked by `git-commit`. It takes no 85parameter, and is invoked after a commit is made. 86 87This hook is meant primarily for notification, and cannot affect 88the outcome of `git-commit`. 89 90[[pre-receive]] 91pre-receive 92----------- 93 94This hook is invoked by `git-receive-pack` on the remote repository, 95which happens when a `git push` is done on a local repository. 96Just before starting to update refs on the remote repository, the 97pre-receive hook is invoked. Its exit status determines the success 98or failure of the update. 99 100This hook executes once for the receive operation. It takes no 101arguments, but for each ref to be updated it receives on standard 102input a line of the format: 103 104 <old-value> SP <new-value> SP <ref-name> LF 105 106where `<old-value>` is the old object name stored in the ref, 107`<new-value>` is the new object name to be stored in the ref and 108`<ref-name>` is the full name of the ref. 109When creating a new ref, `<old-value>` is 40 `0`. 110 111If the hook exits with non-zero status, none of the refs will be 112updated. If the hook exits with zero, updating of individual refs can 113still be prevented by the <<update,'update'>> hook. 114 115Both standard output and standard error output are forwarded to 116`git-send-pack` on the other end, so you can simply `echo` messages 117for the user. 118 119[[update]] 120update 121------ 122 123This hook is invoked by `git-receive-pack` on the remote repository, 124which happens when a `git push` is done on a local repository. 125Just before updating the ref on the remote repository, the update hook 126is invoked. Its exit status determines the success or failure of 127the ref update. 128 129The hook executes once for each ref to be updated, and takes 130three parameters: 131 132 - the name of the ref being updated, 133 - the old object name stored in the ref, 134 - and the new objectname to be stored in the ref. 135 136A zero exit from the update hook allows the ref to be updated. 137Exiting with a non-zero status prevents `git-receive-pack` 138from updating that ref. 139 140This hook can be used to prevent 'forced' update on certain refs by 141making sure that the object name is a commit object that is a 142descendant of the commit object named by the old object name. 143That is, to enforce a "fast forward only" policy. 144 145It could also be used to log the old..new status. However, it 146does not know the entire set of branches, so it would end up 147firing one e-mail per ref when used naively, though. The 148<<post-receive,'post-receive'>> hook is more suited to that. 149 150Another use suggested on the mailing list is to use this hook to 151implement access control which is finer grained than the one 152based on filesystem group. 153 154Both standard output and standard error output are forwarded to 155`git-send-pack` on the other end, so you can simply `echo` messages 156for the user. 157 158The default 'update' hook, when enabled--and with 159`hooks.allowunannotated` config option turned on--prevents 160unannotated tags to be pushed. 161 162[[post-receive]] 163post-receive 164------------ 165 166This hook is invoked by `git-receive-pack` on the remote repository, 167which happens when a `git push` is done on a local repository. 168It executes on the remote repository once after all the refs have 169been updated. 170 171This hook executes once for the receive operation. It takes no 172arguments, but gets the same information as the 173<<pre-receive,'pre-receive'>> 174hook does on its standard input. 175 176This hook does not affect the outcome of `git-receive-pack`, as it 177is called after the real work is done. 178 179This supersedes the <<post-update,'post-update'>> hook in that it get's 180both old and new values of all the refs in addition to their 181names. 182 183Both standard output and standard error output are forwarded to 184`git-send-pack` on the other end, so you can simply `echo` messages 185for the user. 186 187The default 'post-receive' hook is empty, but there is 188a sample script `post-receive-email` provided in the `contrib/hooks` 189directory in git distribution, which implements sending commit 190emails. 191 192[[post-update]] 193post-update 194----------- 195 196This hook is invoked by `git-receive-pack` on the remote repository, 197which happens when a `git push` is done on a local repository. 198It executes on the remote repository once after all the refs have 199been updated. 200 201It takes a variable number of parameters, each of which is the 202name of ref that was actually updated. 203 204This hook is meant primarily for notification, and cannot affect 205the outcome of `git-receive-pack`. 206 207The 'post-update' hook can tell what are the heads that were pushed, 208but it does not know what their original and updated values are, 209so it is a poor place to do log old..new. The 210<<post-receive,'post-receive'>> hook does get both original and 211updated values of the refs. You might consider it instead if you need 212them. 213 214When enabled, the default 'post-update' hook runs 215`git-update-server-info` to keep the information used by dumb 216transports (e.g., HTTP) up-to-date. If you are publishing 217a git repository that is accessible via HTTP, you should 218probably enable this hook. 219 220Both standard output and standard error output are forwarded to 221`git-send-pack` on the other end, so you can simply `echo` messages 222for the user.