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NAME | SYNOPSIS | DESCRIPTION | INVOCATION | INPUT FORMAT | COMMANDS | REF LIST ATTRIBUTES | OPTIONS | SEE ALSO | GIT | COLOPHON |
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GITREMOTE-HELPERS(1) Git Manual GITREMOTE-HELPERS(1)
gitremote-helpers - Helper programs to interact with remote
repositories
git remote-<transport> <repository> [<URL>]
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.
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.
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.
stateless-connect
Experimental; for internal use only. Can attempt to
connect to a remote server for communication using git’s
wire-protocol version 2. See the documentation for the
stateless-connect command for more information.
Supported commands: stateless-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.
stateless-connect
Experimental; for internal use only. Can attempt to
connect to a remote server for communication using git’s
wire-protocol version 2. See the documentation for the
stateless-connect command for more information.
Supported commands: stateless-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 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.
stateless-connect <service>
Experimental; for internal use only. Connects to the given
remote service for communication using git’s wire-protocol
version 2. 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 the service starts. Messages (both
request and response) must consist of zero or more PKT-LINEs,
terminating in a flush packet. The client must not expect the
server to store any state in between request-response pairs.
After the connection ends, the remote helper exits.
Supported if the helper has the "stateless-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.
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.
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 deepen-since <timestamp>
Deepens the history of a shallow repository based on time.
'option deepen-not <ref>
Deepens the history of a shallow repository excluding ref.
Multiple options add up.
option deepen-relative {'true|false}
Deepens the history of a shallow repository relative to
current boundary. Only valid when used with "option depth".
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.
option pushcert {true|false}
GPG sign pushes.
'option push-option <string>
Transmit <string> as a push option. As the push option must
not contain LF or NUL characters, the string is not encoded.
option from-promisor {true|false}
Indicate that these objects are being fetched from a
promisor.
option no-dependents {true|false}
Indicate that only the objects wanted need to be fetched, not
their dependents.
git-remote(1)
git-remote-ext(1)
git-remote-fd(1)
git-remote-testgit(1)
git-fast-import(1)
Part of the git(1) suite
This page is part of the git (Git distributed version control
system) project. Information about the project can be found at
⟨http://git-scm.com/⟩. If you have a bug report for this manual
page, see ⟨http://git-scm.com/community⟩. This page was obtained
from the project's upstream Git repository
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corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
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Git 2.19.1.593.gc670b1 10/28/2018 GITREMOTE-HELPERS(1)
Pages that refer to this page: git-remote-testgit(1)
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