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GITHOOKS(5) Git Manual GITHOOKS(5)

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 test.

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
replacement for 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-value> SP <new-value> SP <ref-name> LF

where <old-value> is the old object name stored in the ref, <new-value>
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-value> 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:

o the name of the ref being updated,

o the old object name stored in the ref,

o 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 to be
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 result 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' to 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:

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

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

o "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-value> SP <new-value> SP <ref-name> LF

where <old-value> is the old object name passed into the reference
transaction, <new-value> 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-value> 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.

DragonFly On-Line Manual Pages

NAME

SYNOPSIS

DESCRIPTION

HOOKS

SEE ALSO

GIT

NOTES