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
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 a helper does not need a specific refspec capability then it should advertise refspec *:*.
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.
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.
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 1.8.3.1 03/23/2016 GITREMOTE-HELPERS(1)
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