NAME

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

SYNOPSIS

       git-receive-pack <directory>

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
       remote repository. For pull operations, see git-fetch-pack(1).

       The command allows for 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

       <directory>
           The repository to sync into.

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