GIT-RECEIVE-PACK(1) Git Manual GIT-RECEIVE-PACK(1)

NAME

git-receive-pack - Receive what is pushed into the repository

SYNOPSIS

git receive-pack <git-dir>

DESCRIPTION

Invoked by git send-pack and updates the repository with the
information fed from the remote end.

This command is usually not invoked directly by the end user. The UI
for the protocol is on the git send-pack side, and the program pair
is meant to be used to push updates to a remote repository. For pull
operations, see git-fetch-pack(1).

The command allows for the creation and fast-forwarding of sha1 refs
(heads/tags) on the remote end (strictly speaking, it is the local
end git-receive-pack runs, but to the user who is sitting at the
send-pack end, it is updating the remote. Confused?)

There are other real-world examples of using update and post-update
hooks found in the Documentation/howto directory.

git-receive-pack honours the receive.denyNonFastForwards config
option, which tells it if updates to a ref should be denied if they
are not fast-forwards.

A number of other receive.* config options are available to tweak its
behavior, see git-config(1).

OPTIONS

<git-dir>
The repository to sync into.

--http-backend-info-refs
Used by git-http-backend(1) to serve up
$GIT_URL/info/refs?service=git-receive-pack requests. See
--http-backend-info-refs in git-upload-pack(1).

PRE-RECEIVE HOOK
Before any ref is updated, if $GIT_DIR/hooks/pre-receive file exists
and is executable, it will be invoked once with no parameters. The
standard input of the hook will be one line per ref to be updated:

sha1-old SP sha1-new SP refname LF

The refname value is relative to $GIT_DIR; e.g. for the master head
this is "refs/heads/master". The two sha1 values before each refname
are the object names for the refname before and after the update.
Refs to be created will have sha1-old equal to 0{40}, while refs to
be deleted will have sha1-new equal to 0{40}, otherwise sha1-old and
sha1-new should be valid objects in the repository.

When accepting a signed push (see git-push(1)), the signed push
certificate is stored in a blob and an environment variable
GIT_PUSH_CERT can be consulted for its object name. See the
description of post-receive hook for an example. In addition, the
certificate is verified using GPG and the result is exported with the
following environment variables:

GIT_PUSH_CERT_SIGNER
The name and the e-mail address of the owner of the key that
signed the push certificate.

GIT_PUSH_CERT_KEY
The GPG key ID of the key that signed the push certificate.

GIT_PUSH_CERT_STATUS
The status of GPG verification of the push certificate, using the
same mnemonic as used in %G? format of git log family of commands
(see git-log(1)).

GIT_PUSH_CERT_NONCE
The nonce string the process asked the signer to include in the
push certificate. If this does not match the value recorded on
the "nonce" header in the push certificate, it may indicate that
the certificate is a valid one that is being replayed from a
separate "git push" session.

GIT_PUSH_CERT_NONCE_STATUS

UNSOLICITED
"git push --signed" sent a nonce when we did not ask it to
send one.

MISSING
"git push --signed" did not send any nonce header.

BAD
"git push --signed" sent a bogus nonce.

OK
"git push --signed" sent the nonce we asked it to send.

SLOP
"git push --signed" sent a nonce different from what we asked
it to send now, but in a previous session. See
GIT_PUSH_CERT_NONCE_SLOP environment variable.

GIT_PUSH_CERT_NONCE_SLOP
"git push --signed" sent a nonce different from what we asked it
to send now, but in a different session whose starting time is
different by this many seconds from the current session. Only
meaningful when GIT_PUSH_CERT_NONCE_STATUS says SLOP. Also read
about receive.certNonceSlop variable in git-config(1).

This hook is called before any refname is updated and before any
fast-forward checks are performed.

If the pre-receive hook exits with a non-zero exit status no updates
will be performed, and the update, post-receive and post-update hooks
will not be invoked either. This can be useful to quickly bail out if
the update is not to be supported.

See the notes on the quarantine environment below.

UPDATE HOOK

Before each ref is updated, if $GIT_DIR/hooks/update file exists and
is executable, it is invoked once per ref, with three parameters:

$GIT_DIR/hooks/update refname sha1-old sha1-new

The refname parameter is relative to $GIT_DIR; e.g. for the master
head this is "refs/heads/master". The two sha1 arguments are the
object names for the refname before and after the update. Note that
the hook is called before the refname is updated, so either sha1-old
is 0{40} (meaning there is no such ref yet), or it should match what
is recorded in refname.

The hook should exit with non-zero status if it wants to disallow
updating the named ref. Otherwise it should exit with zero.

Successful execution (a zero exit status) of this hook does not
ensure the ref will actually be updated, it is only a prerequisite.
As such it is not a good idea to send notices (e.g. email) from this
hook. Consider using the post-receive hook instead.

POST-RECEIVE HOOK
After all refs were updated (or attempted to be updated), if any ref
update was successful, and if $GIT_DIR/hooks/post-receive file exists
and is executable, it will be invoked once with no parameters. The
standard input of the hook will be one line for each successfully
updated ref:

sha1-old SP sha1-new SP refname LF

The refname value is relative to $GIT_DIR; e.g. for the master head
this is "refs/heads/master". The two sha1 values before each refname
are the object names for the refname before and after the update.
Refs that were created will have sha1-old equal to 0{40}, while refs
that were deleted will have sha1-new equal to 0{40}, otherwise
sha1-old and sha1-new should be valid objects in the repository.

The GIT_PUSH_CERT* environment variables can be inspected, just as in
pre-receive hook, after accepting a signed push.

Using this hook, it is easy to generate mails describing the updates
to the repository. This example script sends one mail message per ref
listing the commits pushed to the repository, and logs the push
certificates of signed pushes with good signatures to a logger
service:

#!/bin/sh
# mail out commit update information.
while read oval nval ref
do
if expr "$oval" : '0*$' >/dev/null
then
echo "Created a new ref, with the following commits:"
git rev-list --pretty "$nval"
else
echo "New commits:"
git rev-list --pretty "$nval" "^$oval"
fi |
mail -s "Changes to ref $ref" commit-list@mydomain
done
# log signed push certificate, if any
if test -n "${GIT_PUSH_CERT-}" && test ${GIT_PUSH_CERT_STATUS} = G
then
(
echo expected nonce is ${GIT_PUSH_NONCE}
git cat-file blob ${GIT_PUSH_CERT}
) | mail -s "push certificate from $GIT_PUSH_CERT_SIGNER" push-log@mydomain
fi
exit 0

The exit code from this hook invocation is ignored, however a
non-zero exit code will generate an error message.

Note that it is possible for refname to not have sha1-new when this
hook runs. This can easily occur if another user modifies the ref
after it was updated by git-receive-pack, but before the hook was
able to evaluate it. It is recommended that hooks rely on sha1-new
rather than the current value of refname.

POST-UPDATE HOOK
After all other processing, if at least one ref was updated, and if
$GIT_DIR/hooks/post-update file exists and is executable, then
post-update will be called with the list of refs that have been
updated. This can be used to implement any repository wide cleanup
tasks.

The exit code from this hook invocation is ignored; the only thing
left for git-receive-pack to do at that point is to exit itself
anyway.

This hook can be used, for example, to run git update-server-info if
the repository is packed and is served via a dumb transport.

#!/bin/sh
exec git update-server-info

QUARANTINE ENVIRONMENT

When receive-pack takes in objects, they are placed into a temporary
"quarantine" directory within the $GIT_DIR/objects directory and
migrated into the main object store only after the pre-receive hook
has completed. If the push fails before then, the temporary directory
is removed entirely.

This has a few user-visible effects and caveats:

1. Pushes which fail due to problems with the incoming pack, missing
objects, or due to the pre-receive hook will not leave any
on-disk data. This is usually helpful to prevent repeated failed
pushes from filling up your disk, but can make debugging more
challenging.

2. Any objects created by the pre-receive hook will be created in
the quarantine directory (and migrated only if it succeeds).

3. The pre-receive hook MUST NOT update any refs to point to
quarantined objects. Other programs accessing the repository will
not be able to see the objects (and if the pre-receive hook
fails, those refs would become corrupted). For safety, any ref
updates from within pre-receive are automatically rejected.

SEE ALSO

git-send-pack(1), gitnamespaces(7)

GIT

Part of the git(1) suite

Git 2.48.1 2025-01-13 GIT-RECEIVE-PACK(1)