Ubuntu Manpage: githooks - Hooks used by Git

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NAME

       githooks - Hooks used by Git

SYNOPSIS

       $GIT_DIR/hooks/* (or `git config core.hooksPath`/*)

DESCRIPTION

Hooks are programs you can place in a hooks directory to trigger actions at certain points
in git’s execution. Hooks that don’t have the executable bit set are ignored.

By default the hooks directory is $GIT_DIR/hooks, but that can be changed via the
core.hooksPath configuration variable (see git-config(1)).

Before Git invokes a hook, it changes its working directory to either $GIT_DIR in a bare
repository or the root of the working tree in a non-bare repository. An exception are
hooks triggered during a push (pre-receive, update, post-receive, post-update,
push-to-checkout) which are always executed in $GIT_DIR.

Environment variables, such as GIT_DIR, GIT_WORK_TREE, etc., are exported so that Git
commands run by the hook can correctly locate the repository. If your hook needs to invoke
Git commands in a foreign repository or in a different working tree of the same
repository, then it should clear these environment variables so they do not interfere with
Git operations at the foreign location. For example:

local_desc=$(git describe)
foreign_desc=$(unset $(git rev-parse --local-env-vars); git -C ../foreign-repo describe)

Hooks can get their arguments via the environment, command-line arguments, and stdin. See
the documentation for each hook below for details.

git init may copy hooks to the new repository, depending on its configuration. See the
"TEMPLATE DIRECTORY" section in git-init(1) for details. When the rest of this document
refers to "default hooks" it’s talking about the default template shipped with Git.

The currently supported hooks are described below.

HOOKS

applypatch-msg
This hook is invoked by git-am(1). It takes a single parameter, the name of the file that
holds the proposed commit log message. Exiting with a non-zero status causes git am 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. 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.

pre-applypatch
This hook is invoked by git-am(1). It takes no parameter, and is invoked after the patch
is applied, but before a commit is made.

If it exits with non-zero status, then the working tree will not be committed after
applying the patch.

It can be used to inspect the current working tree and refuse to make a commit if it does
not pass certain tests.

The default pre-applypatch hook, when enabled, runs the pre-commit hook, if the latter is
enabled.

post-applypatch
This hook is invoked by git-am(1). It takes no parameter, and is invoked after the patch
is applied and a commit is made.

This hook is meant primarily for notification, and cannot affect the outcome of git am.

pre-commit
This hook is invoked by git-commit(1), and can be bypassed with the --no-verify option. It
takes no parameters, and is invoked before obtaining the proposed commit log message and
making a commit. Exiting with a non-zero status from this script causes the git commit
command to abort before creating a commit.

The default pre-commit hook, when enabled, catches introduction of lines with trailing
whitespaces and aborts the commit when such a line is found.

All the git commit hooks are invoked with the environment variable GIT_EDITOR=: if the
command will not bring up an editor to modify the commit message.

The default pre-commit hook, when enabled—and with the hooks.allownonascii config option
unset or set to false—prevents the use of non-ASCII filenames.

pre-merge-commit
This hook is invoked by git-merge(1), and can be bypassed with the --no-verify option. It
takes no parameters, and is invoked after the merge has been carried out successfully and
before obtaining the proposed commit log message to make a commit. Exiting with a non-zero
status from this script causes the git merge command to abort before creating a commit.

The default pre-merge-commit hook, when enabled, runs the pre-commit hook, if the latter
is enabled.

This hook is invoked with the environment variable GIT_EDITOR=: if the command will not
bring up an editor to modify the commit message.

If the merge cannot be carried out automatically, the conflicts need to be resolved and
the result committed separately (see git-merge(1)). At that point, this hook will not be
executed, but the pre-commit hook will, if it is enabled.

prepare-commit-msg
This hook is invoked by git-commit(1) right after preparing the default log message, and
before the editor is started.

It takes one to three parameters. The first is the name of the file that contains the
commit log message. The second is the source of the commit message, and can be: message
(if a -m or -F option was given); template (if a -t option was given or the configuration
option commit.template is set); merge (if the commit is a merge or a .git/MERGE_MSG file
exists); squash (if a .git/SQUASH_MSG file exists); or commit, followed by a commit object
name (if a -c, -C or --amend option was given).

If the exit status is non-zero, git commit will abort.

The purpose of the hook is to edit the message file in place, and it is not suppressed by
the --no-verify option. A non-zero exit means a failure of the hook and aborts the commit.
It should not be used as a replacement for the pre-commit hook.

The sample prepare-commit-msg hook that comes with Git removes the help message found in
the commented portion of the commit template.

commit-msg
This hook is invoked by git-commit(1) and git-merge(1), and can be bypassed with the
--no-verify option. It takes a single parameter, the name of the file that holds the
proposed commit log message. Exiting with a non-zero status causes the command to abort.

The default commit-msg hook, when enabled, detects duplicate Signed-off-by trailers, and
aborts the commit if one is found.

post-commit
This hook is invoked by git-commit(1). It takes no parameters, and is invoked after a
commit is made.

This hook is meant primarily for notification, and cannot affect the outcome of git
commit.

pre-rebase
This hook is called by git-rebase(1) and can be used to prevent a branch from getting
rebased. The hook may be called with one or two parameters. The first parameter is the
upstream from which the series was forked. The second parameter is the branch being
rebased, and is not set when rebasing the current branch.

post-checkout
This hook is invoked when a git-checkout(1) or git-switch(1) is run after having updated
the worktree. The hook is given three parameters: the ref of the previous HEAD, the ref of
the new HEAD (which may or may not have changed), and a flag indicating whether the
checkout was a branch checkout (changing branches, flag=1) or a file checkout (retrieving
a file from the index, flag=0). This hook cannot affect the outcome of git switch or git
checkout, other than that the hook’s exit status becomes the exit status of these two
commands.

It is also run after git-clone(1), unless the --no-checkout (-n) option is used. The first
parameter given to the hook is the null-ref, the second the ref of the new HEAD and the
flag is always 1. Likewise for git worktree add unless --no-checkout is used.

This hook can be used to perform repository validity checks, auto-display differences from
the previous HEAD if different, or set working dir metadata properties.

post-merge
This hook is invoked by git-merge(1), which happens when a git pull is done on a local
repository. The hook takes a single parameter, a status flag specifying whether or not the
merge being done was a squash merge. This hook cannot affect the outcome of git merge and
is not executed, if the merge failed due to conflicts.

This hook can be used in conjunction with a corresponding pre-commit hook to save and
restore any form of metadata associated with the working tree (e.g.:
permissions/ownership, ACLS, etc). See contrib/hooks/setgitperms.perl for an example of
how to do this.

pre-push
This hook is called by git-push(1) and can be used to prevent a push from taking place.
The hook is called with two parameters which provide the name and location of the
destination remote, if a named remote is not being used both values will be the same.

Information about what is to be pushed is provided on the hook’s standard input with lines
of the form:

<local-ref> SP <local-object-name> SP <remote-ref> SP <remote-object-name> LF

For instance, if the command git push origin master:foreign were run the hook would
receive a line like the following:

refs/heads/master 67890 refs/heads/foreign 12345

although the full object name would be supplied. If the foreign ref does not yet exist the
<remote-object-name> will be the all-zeroes object name. If a ref is to be deleted, the
<local-ref> will be supplied as (delete) and the <local-object-name> will be the
all-zeroes object name. If the local commit was specified by something other than a name
which could be expanded (such as HEAD~, or an object name) it will be supplied as it was
originally given.

If this hook exits with a non-zero status, git push will abort without pushing anything.
Information about why the push is rejected may be sent to the user by writing to standard
error.

pre-receive
This hook is invoked by git-receive-pack(1) when it reacts to git push and updates
reference(s) in its repository. Just before starting to update refs on the remote
repository, the pre-receive hook is invoked. Its exit status determines the success or
failure of the update.

This hook executes once for the receive operation. It takes no arguments, but for each ref
to be updated it receives on standard input a line of the format:

<old-oid> SP <new-oid> SP <ref-name> LF

where <old-oid> is the old object name stored in the ref, <new-oid> is the new object name
to be stored in the ref and <ref-name> is the full name of the ref. When creating a new
ref, <old-oid> is the all-zeroes object name.

If the hook exits with non-zero status, none of the refs will be updated. If the hook
exits with zero, updating of individual refs can still be prevented by the update hook.

Both standard output and standard error output are forwarded to git send-pack on the other
end, so you can simply echo messages for the user.

The number of push options given on the command line of git push --push-option=... can be
read from the environment variable GIT_PUSH_OPTION_COUNT, and the options themselves are
found in GIT_PUSH_OPTION_0, GIT_PUSH_OPTION_1,... If it is negotiated to not use the push
options phase, the environment variables will not be set. If the client selects to use
push options, but doesn’t transmit any, the count variable will be set to zero,
GIT_PUSH_OPTION_COUNT=0.

See the section on "Quarantine Environment" in git-receive-pack(1) for some caveats.

update
This hook is invoked by git-receive-pack(1) when it reacts to git push and updates
reference(s) in its 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 object name 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 that 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. The
post-receive hook is more suited to that.

In an environment that restricts the users' access only to git commands over the wire,
this hook can be used to implement access control without relying on filesystem ownership
and group membership. See git-shell(1) for how you might use the login shell to restrict
the user’s access to only git commands.

Both standard output and standard error output are forwarded to git send-pack on the other
end, so you can simply echo messages for the user.

The default update hook, when enabled—and with hooks.allowunannotated config option unset
or set to false—prevents unannotated tags from being pushed.

proc-receive
This hook is invoked by git-receive-pack(1). If the server has set the multi-valued config
variable receive.procReceiveRefs, and the commands sent to receive-pack have matching
reference names, these commands will be executed by this hook, instead of by the internal
execute_commands() function. This hook is responsible for updating the relevant references
and reporting the results back to receive-pack.

This hook executes once for the receive operation. It takes no arguments, but uses a
pkt-line format protocol to communicate with receive-pack to read commands, push-options
and send results. In the following example for the protocol, the letter S stands for
receive-pack and the letter H stands for this hook.

# Version and features negotiation.
S: PKT-LINE(version=1\0push-options atomic...)
S: flush-pkt
H: PKT-LINE(version=1\0push-options...)
H: flush-pkt

# Send commands from server to the hook.
S: PKT-LINE(<old-oid> <new-oid> <ref>)
S: ... ...
S: flush-pkt
# Send push-options only if the 'push-options' feature is enabled.
S: PKT-LINE(push-option)
S: ... ...
S: flush-pkt

# Receive results from the hook.
# OK, run this command successfully.
H: PKT-LINE(ok <ref>)
# NO, I reject it.
H: PKT-LINE(ng <ref> <reason>)
# Fall through, let 'receive-pack' execute it.
H: PKT-LINE(ok <ref>)
H: PKT-LINE(option fall-through)
# OK, but has an alternate reference. The alternate reference name
# and other status can be given in option directives.
H: PKT-LINE(ok <ref>)
H: PKT-LINE(option refname <refname>)
H: PKT-LINE(option old-oid <old-oid>)
H: PKT-LINE(option new-oid <new-oid>)
H: PKT-LINE(option forced-update)
H: ... ...
H: flush-pkt

Each command for the proc-receive hook may point to a pseudo-reference and always has a
zero-old as its old-oid, while the proc-receive hook may update an alternate reference and
the alternate reference may exist already with a non-zero old-oid. For this case, this
hook will use "option" directives to report extended attributes for the reference given by
the leading "ok" directive.

The report of the commands of this hook should have the same order as the input. The exit
status of the proc-receive hook only determines the success or failure of the group of
commands sent to it, unless atomic push is in use.

post-receive
This hook is invoked by git-receive-pack(1) when it reacts to git push and updates
reference(s) in its repository. It executes on the remote repository once after all the
refs have been updated.

This hook executes once for the receive operation. It takes no arguments, but gets the
same information as the pre-receive hook does on its standard input.

This hook does not affect the outcome of git receive-pack, as it is called after the real
work is done.

This supersedes the post-update hook in that it gets both old and new values of all the
refs in addition to their names.

Both standard output and standard error output are forwarded to git send-pack on the other
end, so you can simply echo messages for the user.

The default post-receive hook is empty, but there is a sample script post-receive-email
provided in the contrib/hooks directory in Git distribution, which implements sending
commit emails.

post-update
This hook is invoked by git-receive-pack(1) when it reacts to git push and updates
reference(s) in its 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
post-receive hook does get both original and updated values of the refs. You might
consider it instead if you need them.

When enabled, the default post-update hook runs git update-server-info to keep the
information used by dumb 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.

Both standard output and standard error output are forwarded to git send-pack on the other
end, so you can simply echo messages for the user.

reference-transaction
This hook is invoked by any Git command that performs reference updates. It executes
whenever a reference transaction is prepared, committed or aborted and may thus get called
multiple times. The hook does not cover symbolic references (but that may change in the
future).

The hook takes exactly one argument, which is the current state the given reference
transaction is in:

• "prepared": All reference updates have been queued to the transaction and references
were locked on disk.

• "committed": The reference transaction was committed and all references now have their
respective new value.

• "aborted": The reference transaction was aborted, no changes were performed and the
locks have been released.

For each reference update that was added to the transaction, the hook receives on standard
input a line of the format:

<old-oid> SP <new-oid> SP <ref-name> LF

where <old-oid> is the old object name passed into the reference transaction, <new-oid> is
the new object name to be stored in the ref and <ref-name> is the full name of the ref.
When force updating the reference regardless of its current value or when the reference is
to be created anew, <old-oid> is the all-zeroes object name. To distinguish these cases,
you can inspect the current value of <ref-name> via git rev-parse.

The exit status of the hook is ignored for any state except for the "prepared" state. In
the "prepared" state, a non-zero exit status will cause the transaction to be aborted. The
hook will not be called with "aborted" state in that case.

push-to-checkout
This hook is invoked by git-receive-pack(1) when it reacts to git push and updates
reference(s) in its repository, and when the push tries to update the branch that is
currently checked out and the receive.denyCurrentBranch configuration variable is set to
updateInstead. Such a push by default is refused if the working tree and the index of the
remote repository has any difference from the currently checked out commit; when both the
working tree and the index match the current commit, they are updated to match the newly
pushed tip of the branch. This hook is to be used to override the default behaviour.

The hook receives the commit with which the tip of the current branch is going to be
updated. It can exit with a non-zero status to refuse the push (when it does so, it must
not modify the index or the working tree). Or it can make any necessary changes to the
working tree and to the index to bring them to the desired state when the tip of the
current branch is updated to the new commit, and exit with a zero status.

For example, the hook can simply run git read-tree -u -m HEAD "$1" in order to emulate git
fetch that is run in the reverse direction with git push, as the two-tree form of git
read-tree -u -m is essentially the same as git switch or git checkout that switches
branches while keeping the local changes in the working tree that do not interfere with
the difference between the branches.

pre-auto-gc
This hook is invoked by git gc --auto (see git-gc(1)). It takes no parameter, and exiting
with non-zero status from this script causes the git gc --auto to abort.

post-rewrite
This hook is invoked by commands that rewrite commits (git-commit(1) when called with
--amend and git-rebase(1); however, full-history (re)writing tools like git-fast-import(1)
or git-filter-repo[1] typically do not call it!). Its first argument denotes the command
it was invoked by: currently one of amend or rebase. Further command-dependent arguments
may be passed in the future.

The hook receives a list of the rewritten commits on stdin, in the format

<old-object-name> SP <new-object-name> [ SP <extra-info> ] LF

The extra-info is again command-dependent. If it is empty, the preceding SP is also
omitted. Currently, no commands pass any extra-info.

The hook always runs after the automatic note copying (see "notes.rewrite.<command>" in
git-config(1)) has happened, and thus has access to these notes.

The following command-specific comments apply:

rebase
For the squash and fixup operation, all commits that were squashed are listed as being
rewritten to the squashed commit. This means that there will be several lines sharing
the same new-object-name.

The commits are guaranteed to be listed in the order that they were processed by
rebase.

sendemail-validate
This hook is invoked by git-send-email(1).

It takes these command line arguments. They are, 1. the name of the file which holds the
contents of the email to be sent. 2. The name of the file which holds the SMTP headers of
the email.

The SMTP headers are passed in the exact same way as they are passed to the user’s Mail
Transport Agent (MTA). In effect, the email given to the user’s MTA, is the contents of $2
followed by the contents of $1.

An example of a few common headers is shown below. Take notice of the capitalization and
multi-line tab structure.

From: Example <from@example.com>
To: to@example.com
Cc: cc@example.com,
A <author@example.com>,
One <one@example.com>,
two@example.com
Subject: PATCH-STRING

Exiting with a non-zero status causes git send-email to abort before sending any e-mails.

The following environment variables are set when executing the hook.

GIT_SENDEMAIL_FILE_COUNTER
A 1-based counter incremented by one for every file holding an e-mail to be sent
(excluding any FIFOs). This counter does not follow the patch series counter scheme.
It will always start at 1 and will end at GIT_SENDEMAIL_FILE_TOTAL.

GIT_SENDEMAIL_FILE_TOTAL
The total number of files that will be sent (excluding any FIFOs). This counter does
not follow the patch series counter scheme. It will always be equal to the number of
files being sent, whether there is a cover letter or not.

These variables may for instance be used to validate patch series.

The sample sendemail-validate hook that comes with Git checks that all sent patches
(excluding the cover letter) can be applied on top of the upstream repository default
branch without conflicts. Some placeholders are left for additional validation steps to be
performed after all patches of a given series have been applied.

fsmonitor-watchman
This hook is invoked when the configuration option core.fsmonitor is set to
.git/hooks/fsmonitor-watchman or .git/hooks/fsmonitor-watchmanv2 depending on the version
of the hook to use.

Version 1 takes two arguments, a version (1) and the time in elapsed nanoseconds since
midnight, January 1, 1970.

Version 2 takes two arguments, a version (2) and a token that is used for identifying
changes since the token. For watchman this would be a clock id. This version must output
to stdout the new token followed by a NUL before the list of files.

The hook should output to stdout the list of all files in the working directory that may
have changed since the requested time. The logic should be inclusive so that it does not
miss any potential changes. The paths should be relative to the root of the working
directory and be separated by a single NUL.

It is OK to include files which have not actually changed. All changes including
newly-created and deleted files should be included. When files are renamed, both the old
and the new name should be included.

Git will limit what files it checks for changes as well as which directories are checked
for untracked files based on the path names given.

An optimized way to tell git "all files have changed" is to return the filename /.

The exit status determines whether git will use the data from the hook to limit its
search. On error, it will fall back to verifying all files and folders.

p4-changelist
This hook is invoked by git-p4 submit.

The p4-changelist hook is executed after the changelist message has been edited by the
user. It can be bypassed with the --no-verify option. It takes a single parameter, the
name of the file that holds the proposed changelist text. Exiting with a non-zero status
causes the command to abort.

The hook is allowed to edit the changelist file and can be used to normalize the text into
some project standard format. It can also be used to refuse the Submit after inspect the
message file.

Run git-p4 submit --help for details.

p4-prepare-changelist
This hook is invoked by git-p4 submit.

The p4-prepare-changelist hook is executed right after preparing the default changelist
message and before the editor is started. It takes one parameter, the name of the file
that contains the changelist text. Exiting with a non-zero status from the script will
abort the process.

The purpose of the hook is to edit the message file in place, and it is not suppressed by
the --no-verify option. This hook is called even if --prepare-p4-only is set.

Run git-p4 submit --help for details.

p4-post-changelist
This hook is invoked by git-p4 submit.

The p4-post-changelist hook is invoked after the submit has successfully occurred in P4.
It takes no parameters and is meant primarily for notification and cannot affect the
outcome of the git p4 submit action.

Run git-p4 submit --help for details.

p4-pre-submit
This hook is invoked by git-p4 submit. It takes no parameters and nothing from standard
input. Exiting with non-zero status from this script prevent git-p4 submit from launching.
It can be bypassed with the --no-verify command line option. Run git-p4 submit --help for
details.

post-index-change
This hook is invoked when the index is written in read-cache.c do_write_locked_index.

The first parameter passed to the hook is the indicator for the working directory being
updated. "1" meaning working directory was updated or "0" when the working directory was
not updated.

The second parameter passed to the hook is the indicator for whether or not the index was
updated and the skip-worktree bit could have changed. "1" meaning skip-worktree bits could
have been updated and "0" meaning they were not.

Only one parameter should be set to "1" when the hook runs. The hook running passing "1",
"1" should not be possible.

GIT

       Part of the git(1) suite

NOTES

        1. git-filter-repo
           https://github.com/newren/git-filter-repo

NAME

SYNOPSIS

DESCRIPTION

HOOKS

SEE ALSO

GIT

NOTES