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GITREMOTE-HELPERS(1)		  Git Manual		  GITREMOTE-HELPERS(1)

NAME
       gitremote-helpers - Helper programs to interact with remote
       repositories

SYNOPSIS
       git remote-_transport_ <repository> [<URL>]

DESCRIPTION
       Remote helper programs are normally not used directly by	end users, but
       they are	invoked	by Git when it needs to	interact with remote
       repositories Git	does not support natively. A given helper will
       implement a subset of the capabilities documented here. When Git	needs
       to interact with	a repository using a remote helper, it spawns the
       helper as an independent	process, sends commands	to the helper's
       standard	input, and expects results from	the helper's standard output.
       Because a remote	helper runs as an independent process from Git,	there
       is no need to re-link Git to add	a new helper, nor any need to link the
       helper with the implementation of Git.

       Every helper must support the "capabilities" command, which Git uses to
       determine what other commands the helper	will accept. Those other
       commands	can be used to discover	and update remote refs,	transport
       objects between the object database and the remote repository, and
       update the local	object store.

       Git comes with a	"curl" family of remote	helpers, that handle various
       transport protocols, such as git-remote-http, git-remote-https,
       git-remote-ftp and git-remote-ftps. They	implement the capabilities
       fetch, option, and push.

INVOCATION
       Remote helper programs are invoked with one or (optionally) two
       arguments. The first argument specifies a remote	repository as in Git;
       it is either the	name of	a configured remote or a URL. The second
       argument	specifies a URL; it is usually of the form
       _transport_://_address_,	but any	arbitrary string is possible. The
       GIT_DIR environment variable is set up for the remote helper and	can be
       used to determine where to store	additional data	or from	which
       directory to invoke auxiliary Git commands.

       When Git	encounters a URL of the	form _transport_://_address_, where
       _transport_ is a	protocol that it cannot	handle natively, it
       automatically invokes git remote-_transport_ with the full URL as the
       second argument.	If such	a URL is encountered directly on the command
       line, the first argument	is the same as the second, and if it is
       encountered in a	configured remote, the first argument is the name of
       that remote.

       A URL of	the form _transport_::_address_	explicitly instructs Git to
       invoke git remote-_transport_ with _address_ as the second argument. If
       such a URL is encountered directly on the command line, the first
       argument	is _address_, and if it	is encountered in a configured remote,
       the first argument is the name of that remote.

       Additionally, when a configured remote has remote.<name>.vcs set	to
       _transport_, Git	explicitly invokes git remote-_transport_ with _name_
       as the first argument. If set, the second argument is
       remote.<name>.url; otherwise, the second	argument is omitted.

INPUT FORMAT
       Git sends the remote helper a list of commands on standard input, one
       per line. The first command is always the capabilities command, in
       response	to which the remote helper must	print a	list of	the
       capabilities it supports	(see below) followed by	a blank	line. The
       response	to the capabilities command determines what commands Git uses
       in the remainder	of the command stream.

       The command stream is terminated	by a blank line. In some cases
       (indicated in the documentation of the relevant commands), this blank
       line is followed	by a payload in	some other protocol (e.g., the pack
       protocol), while	in others it indicates the end of input.

   Capabilities
       Each remote helper is expected to support only a	subset of commands.
       The operations a	helper supports	are declared to	Git in the response to
       the capabilities	command	(see COMMANDS, below).

       In the following, we list all defined capabilities and for each we list
       which commands a	helper with that capability must provide.

       Capabilities for	Pushing
	   connect
	       Can attempt to connect to git receive-pack (for pushing), git
	       upload-pack, etc	for communication using	git's native packfile
	       protocol. This requires a bidirectional,	full-duplex
	       connection.

	       Supported commands: connect.

	   push
	       Can discover remote refs	and push local commits and the history
	       leading up to them to new or existing remote refs.

	       Supported commands: list	for-push, push.

	   export
	       Can discover remote refs	and push specified objects from	a
	       fast-import stream to remote refs.

	       Supported commands: list	for-push, export.

	   If a	helper advertises connect, Git will use	it if possible and
	   fall	back to	another	capability if the helper requests so when
	   connecting (see the connect command under COMMANDS).	When choosing
	   between push	and export, Git	prefers	push. Other frontends may have
	   some	other order of preference.

	   no-private-update
	       When using the refspec capability, git normally updates the
	       private ref on successful push. This update is disabled when
	       the remote-helper declares the capability no-private-update.

       Capabilities for	Fetching
	   connect
	       Can try to connect to git upload-pack (for fetching), git
	       receive-pack, etc for communication using the Git's native
	       packfile	protocol. This requires	a bidirectional, full-duplex
	       connection.

	       Supported commands: connect.

	   fetch
	       Can discover remote refs	and transfer objects reachable from
	       them to the local object	store.

	       Supported commands: list, fetch.

	   import
	       Can discover remote refs	and output objects reachable from them
	       as a stream in fast-import format.

	       Supported commands: list, import.

	   check-connectivity
	       Can guarantee that when a clone is requested, the received pack
	       is self contained and is	connected.

	   If a	helper advertises connect, Git will use	it if possible and
	   fall	back to	another	capability if the helper requests so when
	   connecting (see the connect command under COMMANDS).	When choosing
	   between fetch and import, Git prefers fetch.	Other frontends	may
	   have	some other order of preference.

       Miscellaneous capabilities
	   option
	       For specifying settings like verbosity (how much	output to
	       write to	stderr)	and depth (how much history is wanted in the
	       case of a shallow clone)	that affect how	other commands are
	       carried out.

	   refspec <refspec>
	       For remote helpers that implement import	or export, this
	       capability allows the refs to be	constrained to a private
	       namespace, instead of writing to	refs/heads or refs/remotes
	       directly. It is recommended that	all importers providing	the
	       import capability use this. It's	mandatory for export.

	       A helper	advertising the	capability refspec
	       refs/heads/*:refs/svn/origin/branches/* is saying that, when it
	       is asked	to import refs/heads/topic, the	stream it outputs will
	       update the refs/svn/origin/branches/topic ref.

	       This capability can be advertised multiple times. The first
	       applicable refspec takes	precedence. The	left-hand of refspecs
	       advertised with this capability must cover all refs reported by
	       the list	command. If no refspec capability is advertised, there
	       is an implied refspec *:*.

	       When writing remote-helpers for decentralized version control
	       systems,	it is advised to keep a	local copy of the repository
	       to interact with, and to	let the	private	namespace refs point
	       to this local repository, while the refs/remotes	namespace is
	       used to track the remote	repository.

	   bidi-import
	       This modifies the import	capability. The	fast-import commands
	       cat-blob	and ls can be used by remote-helpers to	retrieve
	       information about blobs and trees that already exist in
	       fast-import's memory. This requires a channel from fast-import
	       to the remote-helper. If	it is advertised in addition to
	       "import", Git establishes a pipe	from fast-import to the
	       remote-helper's stdin. It follows that Git and fast-import are
	       both connected to the remote-helper's stdin. Because Git	can
	       send multiple commands to the remote-helper it is required that
	       helpers that use	bidi-import buffer all import commands of a
	       batch before sending data to fast-import. This is to prevent
	       mixing commands and fast-import responses on the	helper's
	       stdin.

	   export-marks	<file>
	       This modifies the export	capability, instructing	Git to dump
	       the internal marks table	to <file> when complete. For details,
	       read up on --export-marks=<file>	in git-fast-export(1).

	   import-marks	<file>
	       This modifies the export	capability, instructing	Git to load
	       the marks specified in <file> before processing any input. For
	       details,	read up	on --import-marks=<file> in git-fast-
	       export(1).

	   signed-tags
	       This modifies the export	capability, instructing	Git to pass
	       --signed-tags=verbatim to git-fast-export(1). In	the absence of
	       this capability,	Git will use --signed-tags=warn-strip.

COMMANDS
       Commands	are given by the caller	on the helper's	standard input,	one
       per line.

       capabilities
	   Lists the capabilities of the helper, one per line, ending with a
	   blank line. Each capability may be preceded with *, which marks
	   them	mandatory for Git versions using the remote helper to
	   understand. Any unknown mandatory capability	is a fatal error.

	   Support for this command is mandatory.

       list
	   Lists the refs, one per line, in the	format "<value>	<name> [<attr>
	   ...]". The value may	be a hex sha1 hash, "@<dest>" for a symref, or
	   "?" to indicate that	the helper could not get the value of the ref.
	   A space-separated list of attributes	follows	the name; unrecognized
	   attributes are ignored. The list ends with a	blank line.

	   See REF LIST	ATTRIBUTES for a list of currently defined attributes.

	   Supported if	the helper has the "fetch" or "import" capability.

       list for-push
	   Similar to list, except that	it is used if and only if the caller
	   wants to the	resulting ref list to prepare push commands. A helper
	   supporting both push	and fetch can use this to distinguish for
	   which operation the output of list is going to be used, possibly
	   reducing the	amount of work that needs to be	performed.

	   Supported if	the helper has the "push" or "export" capability.

       option <name> <value>
	   Sets	the transport helper option <name> to <value>. Outputs a
	   single line containing one of ok (option successfully set),
	   unsupported (option not recognized) or error	_msg_ (option <name>
	   is supported	but <value> is not valid for it). Options should be
	   set before other commands, and may influence	the behavior of	those
	   commands.

	   See OPTIONS for a list of currently defined options.

	   Supported if	the helper has the "option" capability.

       fetch <sha1> <name>
	   Fetches the given object, writing the necessary objects to the
	   database. Fetch commands are	sent in	a batch, one per line,
	   terminated with a blank line. Outputs a single blank	line when all
	   fetch commands in the same batch are	complete. Only objects which
	   were	reported in the	output of list with a sha1 may be fetched this
	   way.

	   Optionally may output a lock	_file_ line indicating a file under
	   GIT_DIR/objects/pack	which is keeping a pack	until refs can be
	   suitably updated.

	   If option check-connectivity	is requested, the helper must output
	   connectivity-ok if the clone	is self-contained and connected.

	   Supported if	the helper has the "fetch" capability.

       push +<src>:<dst>
	   Pushes the given local <src>	commit or branch to the	remote branch
	   described by	<dst>. A batch sequence	of one or more push commands
	   is terminated with a	blank line (if there is	only one reference to
	   push, a single push command is followed by a	blank line). For
	   example, the	following would	be two batches of push,	the first
	   asking the remote-helper to push the	local ref master to the	remote
	   ref master and the local HEAD to the	remote branch, and the second
	   asking to push ref foo to ref bar (forced update requested by the
	   +).

	       push refs/heads/master:refs/heads/master
	       push HEAD:refs/heads/branch
	       \n
	       push +refs/heads/foo:refs/heads/bar
	       \n

	   Zero	or more	protocol options may be	entered	after the last push
	   command, before the batch's terminating blank line.

	   When	the push is complete, outputs one or more ok _dst_ or error
	   _dst_ _why_?	 lines to indicate success or failure of each pushed
	   ref.	The status report output is terminated by a blank line.	The
	   option field	<why> may be quoted in a C style string	if it contains
	   an LF.

	   Supported if	the helper has the "push" capability.

       import <name>
	   Produces a fast-import stream which imports the current value of
	   the named ref. It may additionally import other refs	as needed to
	   construct the history efficiently. The script writes	to a
	   helper-specific private namespace. The value	of the named ref
	   should be written to	a location in this namespace derived by
	   applying the	refspecs from the "refspec" capability to the name of
	   the ref.

	   Especially useful for interoperability with a foreign versioning
	   system.

	   Just	like push, a batch sequence of one or more import is
	   terminated with a blank line. For each batch	of import, the remote
	   helper should produce a fast-import stream terminated by a done
	   command.

	   Note	that if	the bidi-import	capability is used the complete	batch
	   sequence has	to be buffered before starting to send data to
	   fast-import to prevent mixing of commands and fast-import responses
	   on the helper's stdin.

	   Supported if	the helper has the "import" capability.

       export
	   Instructs the remote	helper that any	subsequent input is part of a
	   fast-import stream (generated by git	fast-export) containing
	   objects which should	be pushed to the remote.

	   Especially useful for interoperability with a foreign versioning
	   system.

	   The export-marks and	import-marks capabilities, if specified,
	   affect this command in so far as they are passed on to git
	   fast-export,	which then will	load/store a table of marks for	local
	   objects. This can be	used to	implement for incremental operations.

	   Supported if	the helper has the "export" capability.

       connect <service>
	   Connects to given service. Standard input and standard output of
	   helper are connected	to specified service (git prefix is included
	   in service name so e.g. fetching uses git-upload-pack as service)
	   on remote side. Valid replies to this command are empty line
	   (connection established), fallback (no smart	transport support,
	   fall	back to	dumb transports) and just exiting with error message
	   printed (can't connect, don't bother	trying to fall back). After
	   line	feed terminating the positive (empty) response,	the output of
	   service starts. After the connection	ends, the remote helper	exits.

	   Supported if	the helper has the "connect" capability.

       If a fatal error	occurs,	the program writes the error message to	stderr
       and exits. The caller should expect that	a suitable error message has
       been printed if the child closes	the connection without completing a
       valid response for the current command.

       Additional commands may be supported, as	may be determined from
       capabilities reported by	the helper.

REF LIST ATTRIBUTES
       The list	command	produces a list	of refs	in which each ref may be
       followed	by a list of attributes. The following ref list	attributes are
       defined.

       unchanged
	   This	ref is unchanged since the last	import or fetch, although the
	   helper cannot necessarily determine what value that produced.

OPTIONS
       The following options are defined and (under suitable circumstances)
       set by Git if the remote	helper has the option capability.

       option verbosity	<n>
	   Changes the verbosity of messages displayed by the helper. A	value
	   of 0	for <n>	means that processes operate quietly, and the helper
	   produces only error output. 1 is the	default	level of verbosity,
	   and higher values of	<n> correspond to the number of	-v flags
	   passed on the command line.

       option progress {true|false}
	   Enables (or disables) progress messages displayed by	the transport
	   helper during a command.

       option depth <depth>
	   Deepens the history of a shallow repository.

       'option deepen-since <timestamp>
	   Deepens the history of a shallow repository based on	time.

       'option deepen-not <ref>
	   Deepens the history of a shallow repository excluding ref. Multiple
	   options add up.

       option deepen-relative {'true|false}
	   Deepens the history of a shallow repository relative	to current
	   boundary. Only valid	when used with "option depth".

       option followtags {true|false}
	   If enabled the helper should	automatically fetch annotated tag
	   objects if the object the tag points	at was transferred during the
	   fetch command. If the tag is	not fetched by the helper a second
	   fetch command will usually be sent to ask for the tag specifically.
	   Some	helpers	may be able to use this	option to avoid	a second
	   network connection.

       option dry-run {true|false}: If true, pretend the operation completed
       successfully, but don't actually	change any repository data. For	most
       helpers this only applies to the	push, if supported.

       option servpath _c-style-quoted-path_
	   Sets	service	path (--upload-pack, --receive-pack etc.) for next
	   connect. Remote helper may support this option, but must not	rely
	   on this option being	set before connect request occurs.

       option check-connectivity {true|false}
	   Request the helper to check connectivity of a clone.

       option force {true|false}
	   Request the helper to perform a force update. Defaults to false.

       option cloning {true|false}
	   Notify the helper this is a clone request (i.e. the current
	   repository is guaranteed empty).

       option update-shallow {true|false}
	   Allow to extend .git/shallow	if the new refs	require	it.

       option pushcert {true|false}
	   GPG sign pushes.

       'option push-option <string>
	   Transmit <string> as	a push option. As the push option must not
	   contain LF or NUL characters, the string is not encoded.

SEE ALSO
       git-remote(1)

       git-remote-ext(1)

       git-remote-fd(1)

       git-remote-testgit(1)

       git-fast-import(1)

GIT
       Part of the git(1) suite

Git 2.13.2			  06/24/2017		  GITREMOTE-HELPERS(1)

NAME | SYNOPSIS | DESCRIPTION | INVOCATION | INPUT FORMAT | COMMANDS | REF LIST ATTRIBUTES | OPTIONS | SEE ALSO | GIT

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