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+gitremote-helpers(7)
+====================
+
+NAME
+----
+gitremote-helpers - Helper programs to interact with remote repositories
+
+SYNOPSIS
+--------
+[verse]
+'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'.
+
+'stateless-connect'::
+	Experimental; for internal use only.
+	Can attempt to connect to a remote server for communication
+	using git's wire-protocol version 2.  See the documentation
+	for the stateless-connect command for more information.
++
+Supported commands: 'stateless-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'.
+
+'stateless-connect'::
+	Experimental; for internal use only.
+	Can attempt to connect to a remote server for communication
+	using git's wire-protocol version 2.  See the documentation
+	for the stateless-connect command for more information.
++
+Supported commands: 'stateless-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 linkgit: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 linkgit:git-fast-export[1].
+
+'signed-tags'::
+	This modifies the 'export' capability, instructing Git to pass
+	`--signed-tags=verbatim` to linkgit: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.
+
+'stateless-connect' <service>::
+	Experimental; for internal use only.
+	Connects to the given remote service for communication using
+	git's wire-protocol version 2.  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 the service starts.  Messages
+	(both request and response) must consist of zero or more
+	PKT-LINEs, terminating in a flush packet. The client must not
+	expect the server to store any state in between request-response
+	pairs.  After the connection ends, the remote helper exits.
++
+Supported if the helper has the "stateless-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.
+
+'option from-promisor' {'true'|'false'}::
+	Indicate that these objects are being fetched from a promisor.
+
+'option no-dependents' {'true'|'false'}::
+	Indicate that only the objects wanted need to be fetched, not
+	their dependents.
+
+SEE ALSO
+--------
+linkgit:git-remote[1]
+
+linkgit:git-remote-ext[1]
+
+linkgit:git-remote-fd[1]
+
+linkgit:git-fast-import[1]
+
+GIT
+---
+Part of the linkgit:git[1] suite