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 64All the `git-commit` hooks are invoked with the environment 65variable `GIT_EDITOR=:` if the command will not bring up an editor 66to modify the commit message. 67 68prepare-commit-msg 69------------------ 70 71This hook is invoked by `git-commit` right after preparing the 72default log message, and before the editor is started. 73 74It takes one to three parameters. The first is the name of the file 75that the commit log message. The second is the source of the commit 76message, and can be: `message` (if a `\-m` or `\-F` option was 77given); `template` (if a `\-t` option was given or the 78configuration option `commit.template` is set); `merge` (if the 79commit is a merge or a `.git/MERGE_MSG` file exists); `squash` 80(if a `.git/SQUASH_MSG` file exists); or `commit`, followed by 81a commit SHA1 (if a `\-c`, `\-C` or `\--amend` option was given). 82 83If the exit status is non-zero, `git-commit` will abort. 84 85The purpose of the hook is to edit the message file in place, and 86it is not suppressed by the `\--no-verify` option. A non-zero exit 87means a failure of the hook and aborts the commit. It should not 88be used as replacement for pre-commit hook. 89 90The sample `prepare-commit-msg` hook that comes with git comments 91out the `Conflicts:` part of a merge's commit message. 92 93commit-msg 94---------- 95 96This hook is invoked by `git-commit`, and can be bypassed 97with `\--no-verify` option. It takes a single parameter, the 98name of the file that holds the proposed commit log message. 99Exiting with non-zero status causes the `git-commit` to 100abort. 101 102The hook is allowed to edit the message file in place, and can 103be used to normalize the message into some project standard 104format (if the project has one). It can also be used to refuse 105the commit after inspecting the message file. 106 107The default 'commit-msg' hook, when enabled, detects duplicate 108"Signed-off-by" lines, and aborts the commit if one is found. 109 110post-commit 111----------- 112 113This hook is invoked by `git-commit`. It takes no 114parameter, and is invoked after a commit is made. 115 116This hook is meant primarily for notification, and cannot affect 117the outcome of `git-commit`. 118 119post-checkout 120----------- 121 122This hook is invoked when a `git-checkout` is run after having updated the 123worktree. The hook is given three parameters: the ref of the previous HEAD, 124the ref of the new HEAD (which may or may not have changed), and a flag 125indicating whether the checkout was a branch checkout (changing branches, 126flag=1) or a file checkout (retrieving a file from the index, flag=0). 127This hook cannot affect the outcome of `git-checkout`. 128 129This hook can be used to perform repository validity checks, auto-display 130differences from the previous HEAD if different, or set working dir metadata 131properties. 132 133post-merge 134----------- 135 136This hook is invoked by `git-merge`, which happens when a `git pull` 137is done on a local repository. The hook takes a single parameter, a status 138flag specifying whether or not the merge being done was a squash merge. 139This hook cannot affect the outcome of `git-merge`. 140 141This hook can be used in conjunction with a corresponding pre-commit hook to 142save and restore any form of metadata associated with the working tree 143(eg: permissions/ownership, ACLS, etc). See contrib/hooks/setgitperms.perl 144for an example of how to do this. 145 146[[pre-receive]] 147pre-receive 148----------- 149 150This hook is invoked by `git-receive-pack` on the remote repository, 151which happens when a `git push` is done on a local repository. 152Just before starting to update refs on the remote repository, the 153pre-receive hook is invoked. Its exit status determines the success 154or failure of the update. 155 156This hook executes once for the receive operation. It takes no 157arguments, but for each ref to be updated it receives on standard 158input a line of the format: 159 160 <old-value> SP <new-value> SP <ref-name> LF 161 162where `<old-value>` is the old object name stored in the ref, 163`<new-value>` is the new object name to be stored in the ref and 164`<ref-name>` is the full name of the ref. 165When creating a new ref, `<old-value>` is 40 `0`. 166 167If the hook exits with non-zero status, none of the refs will be 168updated. If the hook exits with zero, updating of individual refs can 169still be prevented by the <<update,'update'>> hook. 170 171Both standard output and standard error output are forwarded to 172`git-send-pack` on the other end, so you can simply `echo` messages 173for the user. 174 175[[update]] 176update 177------ 178 179This hook is invoked by `git-receive-pack` on the remote repository, 180which happens when a `git push` is done on a local repository. 181Just before updating the ref on the remote repository, the update hook 182is invoked. Its exit status determines the success or failure of 183the ref update. 184 185The hook executes once for each ref to be updated, and takes 186three parameters: 187 188 - the name of the ref being updated, 189 - the old object name stored in the ref, 190 - and the new objectname to be stored in the ref. 191 192A zero exit from the update hook allows the ref to be updated. 193Exiting with a non-zero status prevents `git-receive-pack` 194from updating that ref. 195 196This hook can be used to prevent 'forced' update on certain refs by 197making sure that the object name is a commit object that is a 198descendant of the commit object named by the old object name. 199That is, to enforce a "fast forward only" policy. 200 201It could also be used to log the old..new status. However, it 202does not know the entire set of branches, so it would end up 203firing one e-mail per ref when used naively, though. The 204<<post-receive,'post-receive'>> hook is more suited to that. 205 206Another use suggested on the mailing list is to use this hook to 207implement access control which is finer grained than the one 208based on filesystem group. 209 210Both standard output and standard error output are forwarded to 211`git-send-pack` on the other end, so you can simply `echo` messages 212for the user. 213 214The default 'update' hook, when enabled--and with 215`hooks.allowunannotated` config option turned on--prevents 216unannotated tags to be pushed. 217 218[[post-receive]] 219post-receive 220------------ 221 222This hook is invoked by `git-receive-pack` on the remote repository, 223which happens when a `git push` is done on a local repository. 224It executes on the remote repository once after all the refs have 225been updated. 226 227This hook executes once for the receive operation. It takes no 228arguments, but gets the same information as the 229<<pre-receive,'pre-receive'>> 230hook does on its standard input. 231 232This hook does not affect the outcome of `git-receive-pack`, as it 233is called after the real work is done. 234 235This supersedes the <<post-update,'post-update'>> hook in that it gets 236both old and new values of all the refs in addition to their 237names. 238 239Both standard output and standard error output are forwarded to 240`git-send-pack` on the other end, so you can simply `echo` messages 241for the user. 242 243The default 'post-receive' hook is empty, but there is 244a sample script `post-receive-email` provided in the `contrib/hooks` 245directory in git distribution, which implements sending commit 246emails. 247 248[[post-update]] 249post-update 250----------- 251 252This hook is invoked by `git-receive-pack` on the remote repository, 253which happens when a `git push` is done on a local repository. 254It executes on the remote repository once after all the refs have 255been updated. 256 257It takes a variable number of parameters, each of which is the 258name of ref that was actually updated. 259 260This hook is meant primarily for notification, and cannot affect 261the outcome of `git-receive-pack`. 262 263The 'post-update' hook can tell what are the heads that were pushed, 264but it does not know what their original and updated values are, 265so it is a poor place to do log old..new. The 266<<post-receive,'post-receive'>> hook does get both original and 267updated values of the refs. You might consider it instead if you need 268them. 269 270When enabled, the default 'post-update' hook runs 271`git-update-server-info` to keep the information used by dumb 272transports (e.g., HTTP) up-to-date. If you are publishing 273a git repository that is accessible via HTTP, you should 274probably enable this hook. 275 276Both standard output and standard error output are forwarded to 277`git-send-pack` on the other end, so you can simply `echo` messages 278for the user.