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 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.

SEE ALSO
       git-remote(1)

       git-remote-testgit(1)

GIT
       Part of the git(1) suite



Git 2.1.4                         03/19/2016              GITREMOTE-HELPERS(1)
