NAME
gitremote-helpers - Helper programs to interact with remote repositories
SYNOPSIS
git remote-<transport>\n <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
Supported commands: connect.
stateless-connect
Supported commands: stateless-connect.
push
Supported commands: list for-push, push.
export
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
Capabilities for Fetching
connect
Supported commands: connect.
stateless-connect
Supported commands: stateless-connect.
fetch
Supported commands: list, fetch.
import
Supported commands: list, import.
check-connectivity
get
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
refspec <refspec>
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
export-marks <file>
import-marks <file>
signed-tags
object-format
COMMANDS
Commands are given by the caller on the helper’s standard input, one per line.
capabilities
Support for this command is mandatory.
list
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
Supported if the helper has the "push" or "export" capability.
option <name> <value>
See OPTIONS for a list of currently defined options.
Supported if the helper has the "option" capability.
fetch <sha1> <name>
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>
push refs/heads/master:refs/heads/master
push HEAD:refs/heads/branch
\n
push +refs/heads/foo:refs/heads/bar
\nZero 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>
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
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>
Supported if the helper has the "connect" capability.
stateless-connect <service>
Supported if the helper has the "stateless-connect" capability.
get <uri> <path>
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
REF LIST KEYWORDS
The list command may produce a list of key-value pairs. The following keys are defined.
object-format
OPTIONS
The following options are defined and (under suitable circumstances) set by Git if the remote helper has the option capability.
option verbosity <n>
option progress {true|false}
option depth <depth>
option deepen-since <timestamp>
option deepen-not <ref>
option deepen-relative {true|false}
option followtags {true|false}
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>
option check-connectivity {true|false}
option force {true|false}
option cloning {true|false}
option update-shallow {true|false}
option pushcert {true|false}
option push-option <string>
option from-promisor {true|false}
option no-dependents {true|false}
option atomic {true|false}
option object-format true
SEE ALSO
git-remote(1)
git-remote-ext(1)
git-remote-fd(1)
git-fast-import(1)
GIT
Part of the git(1) suite