# gitremote-helpers

## 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_.
    
               _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.
    
               _get_
                   Can use the _get_ command to download a file from a given
                   URI.
    
               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**.
    
               _object-format_
                   This indicates that the helper is able to interact with
                   the remote side using an explicit hash algorithm
                   extension.
    


## 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, ":<keyword> <value>" for a key-value pair, 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. See REF LIST KEYWORDS for a list of currently
               defined keywords.
    
               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 the full
               path of a file under **$GIT_DIR/objects/pack** which is keeping a
               pack until refs can be suitably updated. The path must end
               with **.keep**. This is a mechanism to name a <pack,idx,keep>
               tuple by giving only the keep component. The kept pack will
               not be deleted by a concurrent repack, even though its objects
               may not be referenced until the fetch completes. The **.keep**
               file will be deleted at the conclusion of the fetch.
    
               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. Response messages will then
               have a response end packet after the flush packet to indicate
               the end of a response. 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.
    
           _get_ <uri> <path>
               Downloads the file from the given _< uri>_ to the given _< path>_.
               If _< path>_**.temp** exists, then Git assumes that the **.temp** file is
               a partial download from a previous attempt and will resume the
               download from that position.
    
           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.
    


## REF LIST KEYWORDS



           The _list_ command may produce a list of key-value pairs. The
           following keys are defined.
    
           _object-format_
               The refs are using the given hash algorithm. This keyword is
               only used if the server and client both support the
               object-format extension.
    


## 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.
    
           _option atomic_ {_true_ |_false_}
               When pushing, request the remote server to update refs in a
               single atomic transaction. If successful, all refs will be
               updated, or none will. If the remote side does not support
               this capability, the push will fail.
    
           _option object-format true_
               Indicate that the caller wants hash algorithm information to
               be passed back from the remote. This mode is used when
               fetching refs.
    


## GIT



           Part of the git(1) suite
    


* * *