git-remote-helpers

GIT-REMOTE-HELPERS(1)              Git Manual              GIT-REMOTE-HELPERS(1)



NAME
       git-remote-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.

       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.

           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>
               This modifies the import capability, allowing the produced
               fast-import stream to modify refs in 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.

               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 *:*.

           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).

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.

           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.

SEE ALSO
       git-remote(1)

       git-remote-testgit(1)

GIT
       Part of the git(1) suite



Git 1.8.1.4                        02/19/2013              GIT-REMOTE-HELPERS(1)