GIT-REMOTE-HELPERS(1) Git Manual GIT-REMOTE-HELPERS(1)NAMEgit-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.
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).
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.
connect
For fetching and pushing using git’s native packfile protocol that
requires a bidirectional, full-duplex connection.
push
For listing remote refs and pushing specified objects from the
local object store to remote refs.
fetch
For listing remote refs and fetching the associated history to the
local object store.
import
For listing remote refs and fetching the associated history as a
fast-import stream.
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 *:*.
Capabilities for Pushing
connect
Can attempt to connect to git receive-pack (for pushing), git
upload-pack, etc for communication using the packfile protocol.
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.
If a helper advertises both connect and push, git will use connect if
possible and fall back to push if the helper requests so when
connecting (see the connect command under COMMANDS).
Capabilities for Fetching
connect
Can try to connect to git upload-pack (for fetching), git
receive-pack, etc for communication using the packfile protocol.
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.
refspec <refspec>
This modifies the import capability.
A helper advertising refspec
refs/heads/*:refs/svn/origin/branches/* in its capabilities is
saying that, when it handles 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 *:*.
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.
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 version using the remote helper to
understand (unknown mandatory capability is fatal error).
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.
If push is supported this may be called as list for-push to obtain
the current refs prior to sending one or more push commands to the
helper.
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.
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 ref 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.
Supported if the helper has the "import" 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
for-push
The caller wants to use the ref list to prepare push commands. A
helper might chose to acquire the ref list by opening a different
type of connection to the destination.
unchanged
This ref is unchanged since the last import or fetch, although the
helper cannot necessarily determine what value that produced.
OPTIONS
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 ALSOgit-remote(1)git-remote-testgit(1)GIT
Part of the git(1) suite
Git 1.7.9.4 03/13/2012 GIT-REMOTE-HELPERS(1)
