git-receive-pack

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 <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

Git 2.25.1                        04/26/2023               GIT-RECEIVE-PACK(1)