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https://github.com/git/git
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![Derrick Stolee](/assets/img/avatar_default.png)
A future change will want a way to download a file over HTTP(S) using the simplest of download mechanisms. We do not want to assume that the server on the other side understands anything about the Git protocol but could be a simple static web server. Create the new 'get' capability for the remote helpers which advertises that the 'get' command is avalable. A caller can send a line containing 'get <url> <path>' to download the file at <url> into the file at <path>. Reviewed-by: Josh Steadmon <steadmon@google.com> Signed-off-by: Derrick Stolee <derrickstolee@github.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
566 lines
21 KiB
Plaintext
566 lines
21 KiB
Plaintext
gitremote-helpers(7)
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====================
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NAME
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----
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gitremote-helpers - Helper programs to interact with remote repositories
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SYNOPSIS
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--------
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[verse]
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'git remote-<transport>' <repository> [<URL>]
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DESCRIPTION
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-----------
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Remote helper programs are normally not used directly by end users,
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but they are invoked by Git when it needs to interact with remote
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repositories Git does not support natively. A given helper will
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implement a subset of the capabilities documented here. When Git
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needs to interact with a repository using a remote helper, it spawns
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the helper as an independent process, sends commands to the helper's
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standard input, and expects results from the helper's standard
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output. Because a remote helper runs as an independent process from
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Git, there is no need to re-link Git to add a new helper, nor any
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need to link the helper with the implementation of Git.
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Every helper must support the "capabilities" command, which Git
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uses to determine what other commands the helper will accept. Those
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other commands can be used to discover and update remote refs,
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transport objects between the object database and the remote repository,
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and update the local object store.
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Git comes with a "curl" family of remote helpers, that handle various
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transport protocols, such as 'git-remote-http', 'git-remote-https',
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'git-remote-ftp' and 'git-remote-ftps'. They implement the capabilities
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'fetch', 'option', and 'push'.
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INVOCATION
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----------
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Remote helper programs are invoked with one or (optionally) two
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arguments. The first argument specifies a remote repository as in Git;
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it is either the name of a configured remote or a URL. The second
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argument specifies a URL; it is usually of the form
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'<transport>://<address>', but any arbitrary string is possible.
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The `GIT_DIR` environment variable is set up for the remote helper
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and can be used to determine where to store additional data or from
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which directory to invoke auxiliary Git commands.
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When Git encounters a URL of the form '<transport>://<address>', where
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'<transport>' is a protocol that it cannot handle natively, it
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automatically invokes 'git remote-<transport>' with the full URL as
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the second argument. If such a URL is encountered directly on the
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command line, the first argument is the same as the second, and if it
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is encountered in a configured remote, the first argument is the name
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of that remote.
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A URL of the form '<transport>::<address>' explicitly instructs Git to
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invoke 'git remote-<transport>' with '<address>' as the second
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argument. If such a URL is encountered directly on the command line,
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the first argument is '<address>', and if it is encountered in a
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configured remote, the first argument is the name of that remote.
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Additionally, when a configured remote has `remote.<name>.vcs` set to
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'<transport>', Git explicitly invokes 'git remote-<transport>' with
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'<name>' as the first argument. If set, the second argument is
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`remote.<name>.url`; otherwise, the second argument is omitted.
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INPUT FORMAT
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------------
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Git sends the remote helper a list of commands on standard input, one
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per line. The first command is always the 'capabilities' command, in
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response to which the remote helper must print a list of the
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capabilities it supports (see below) followed by a blank line. The
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response to the capabilities command determines what commands Git uses
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in the remainder of the command stream.
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The command stream is terminated by a blank line. In some cases
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(indicated in the documentation of the relevant commands), this blank
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line is followed by a payload in some other protocol (e.g., the pack
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protocol), while in others it indicates the end of input.
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Capabilities
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~~~~~~~~~~~~
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Each remote helper is expected to support only a subset of commands.
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The operations a helper supports are declared to Git in the response
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to the `capabilities` command (see COMMANDS, below).
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In the following, we list all defined capabilities and for
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each we list which commands a helper with that capability
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must provide.
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Capabilities for Pushing
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^^^^^^^^^^^^^^^^^^^^^^^^
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'connect'::
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Can attempt to connect to 'git receive-pack' (for pushing),
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'git upload-pack', etc for communication using
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git's native packfile protocol. This
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requires a bidirectional, full-duplex connection.
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+
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Supported commands: 'connect'.
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'stateless-connect'::
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Experimental; for internal use only.
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Can attempt to connect to a remote server for communication
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using git's wire-protocol version 2. See the documentation
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for the stateless-connect command for more information.
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+
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Supported commands: 'stateless-connect'.
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'push'::
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Can discover remote refs and push local commits and the
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history leading up to them to new or existing remote refs.
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+
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Supported commands: 'list for-push', 'push'.
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'export'::
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Can discover remote refs and push specified objects from a
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fast-import stream to remote refs.
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+
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Supported commands: 'list for-push', 'export'.
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If a helper advertises 'connect', Git will use it if possible and
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fall back to another capability if the helper requests so when
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connecting (see the 'connect' command under COMMANDS).
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When choosing between 'push' and 'export', Git prefers 'push'.
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Other frontends may have some other order of preference.
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'no-private-update'::
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When using the 'refspec' capability, git normally updates the
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private ref on successful push. This update is disabled when
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the remote-helper declares the capability 'no-private-update'.
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Capabilities for Fetching
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^^^^^^^^^^^^^^^^^^^^^^^^^
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'connect'::
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Can try to connect to 'git upload-pack' (for fetching),
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'git receive-pack', etc for communication using the
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Git's native packfile protocol. This
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requires a bidirectional, full-duplex connection.
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+
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Supported commands: 'connect'.
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'stateless-connect'::
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Experimental; for internal use only.
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Can attempt to connect to a remote server for communication
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using git's wire-protocol version 2. See the documentation
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for the stateless-connect command for more information.
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+
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Supported commands: 'stateless-connect'.
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'fetch'::
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Can discover remote refs and transfer objects reachable from
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them to the local object store.
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+
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Supported commands: 'list', 'fetch'.
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'import'::
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Can discover remote refs and output objects reachable from
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them as a stream in fast-import format.
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+
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Supported commands: 'list', 'import'.
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'check-connectivity'::
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Can guarantee that when a clone is requested, the received
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pack is self contained and is connected.
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'get'::
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Can use the 'get' command to download a file from a given URI.
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If a helper advertises 'connect', Git will use it if possible and
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fall back to another capability if the helper requests so when
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connecting (see the 'connect' command under COMMANDS).
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When choosing between 'fetch' and 'import', Git prefers 'fetch'.
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Other frontends may have some other order of preference.
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Miscellaneous capabilities
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^^^^^^^^^^^^^^^^^^^^^^^^^^
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'option'::
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For specifying settings like `verbosity` (how much output to
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write to stderr) and `depth` (how much history is wanted in the
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case of a shallow clone) that affect how other commands are
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carried out.
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'refspec' <refspec>::
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For remote helpers that implement 'import' or 'export', this capability
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allows the refs to be constrained to a private namespace, instead of
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writing to refs/heads or refs/remotes directly.
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It is recommended that all importers providing the 'import'
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capability use this. It's mandatory for 'export'.
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+
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A helper advertising the capability
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`refspec refs/heads/*:refs/svn/origin/branches/*`
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is saying that, when it is asked to `import refs/heads/topic`, the
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stream it outputs will update the `refs/svn/origin/branches/topic`
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ref.
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+
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This capability can be advertised multiple times. The first
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applicable refspec takes precedence. The left-hand of refspecs
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advertised with this capability must cover all refs reported by
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the list command. If no 'refspec' capability is advertised,
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there is an implied `refspec *:*`.
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+
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When writing remote-helpers for decentralized version control
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systems, it is advised to keep a local copy of the repository to
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interact with, and to let the private namespace refs point to this
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local repository, while the refs/remotes namespace is used to track
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the remote repository.
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'bidi-import'::
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This modifies the 'import' capability.
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The fast-import commands 'cat-blob' and 'ls' can be used by remote-helpers
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to retrieve information about blobs and trees that already exist in
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fast-import's memory. This requires a channel from fast-import to the
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remote-helper.
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If it is advertised in addition to "import", Git establishes a pipe from
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fast-import to the remote-helper's stdin.
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It follows that Git and fast-import are both connected to the
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remote-helper's stdin. Because Git can send multiple commands to
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the remote-helper it is required that helpers that use 'bidi-import'
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buffer all 'import' commands of a batch before sending data to fast-import.
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This is to prevent mixing commands and fast-import responses on the
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helper's stdin.
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'export-marks' <file>::
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This modifies the 'export' capability, instructing Git to dump the
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internal marks table to <file> when complete. For details,
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read up on `--export-marks=<file>` in linkgit:git-fast-export[1].
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'import-marks' <file>::
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This modifies the 'export' capability, instructing Git to load the
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marks specified in <file> before processing any input. For details,
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read up on `--import-marks=<file>` in linkgit:git-fast-export[1].
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'signed-tags'::
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This modifies the 'export' capability, instructing Git to pass
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`--signed-tags=verbatim` to linkgit:git-fast-export[1]. In the
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absence of this capability, Git will use `--signed-tags=warn-strip`.
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'object-format'::
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This indicates that the helper is able to interact with the remote
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side using an explicit hash algorithm extension.
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COMMANDS
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--------
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Commands are given by the caller on the helper's standard input, one per line.
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'capabilities'::
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Lists the capabilities of the helper, one per line, ending
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with a blank line. Each capability may be preceded with '*',
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which marks them mandatory for Git versions using the remote
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helper to understand. Any unknown mandatory capability is a
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fatal error.
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+
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Support for this command is mandatory.
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'list'::
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Lists the refs, one per line, in the format "<value> <name>
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[<attr> ...]". The value may be a hex sha1 hash, "@<dest>" for
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a symref, ":<keyword> <value>" for a key-value pair, or
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"?" to indicate that the helper could not get the value of the
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ref. A space-separated list of attributes follows the name;
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unrecognized attributes are ignored. The list ends with a
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blank line.
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+
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See REF LIST ATTRIBUTES for a list of currently defined attributes.
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See REF LIST KEYWORDS for a list of currently defined keywords.
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+
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Supported if the helper has the "fetch" or "import" capability.
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'list for-push'::
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Similar to 'list', except that it is used if and only if
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the caller wants to the resulting ref list to prepare
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push commands.
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A helper supporting both push and fetch can use this
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to distinguish for which operation the output of 'list'
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is going to be used, possibly reducing the amount
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of work that needs to be performed.
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+
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Supported if the helper has the "push" or "export" capability.
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'option' <name> <value>::
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Sets the transport helper option <name> to <value>. Outputs a
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single line containing one of 'ok' (option successfully set),
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'unsupported' (option not recognized) or 'error <msg>'
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(option <name> is supported but <value> is not valid
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for it). Options should be set before other commands,
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and may influence the behavior of those commands.
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+
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See OPTIONS for a list of currently defined options.
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+
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Supported if the helper has the "option" capability.
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'fetch' <sha1> <name>::
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Fetches the given object, writing the necessary objects
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to the database. Fetch commands are sent in a batch, one
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per line, terminated with a blank line.
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Outputs a single blank line when all fetch commands in the
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same batch are complete. Only objects which were reported
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in the output of 'list' with a sha1 may be fetched this way.
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+
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Optionally may output a 'lock <file>' line indicating the full path of
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a file under `$GIT_DIR/objects/pack` which is keeping a pack until
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refs can be suitably updated. The path must end with `.keep`. This is
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a mechanism to name a <pack,idx,keep> tuple by giving only the keep
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component. The kept pack will not be deleted by a concurrent repack,
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even though its objects may not be referenced until the fetch completes.
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The `.keep` file will be deleted at the conclusion of the fetch.
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+
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If option 'check-connectivity' is requested, the helper must output
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'connectivity-ok' if the clone is self-contained and connected.
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+
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Supported if the helper has the "fetch" capability.
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'push' +<src>:<dst>::
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Pushes the given local <src> commit or branch to the
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remote branch described by <dst>. A batch sequence of
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one or more 'push' commands is terminated with a blank line
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(if there is only one reference to push, a single 'push' command
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is followed by a blank line). For example, the following would
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be two batches of 'push', the first asking the remote-helper
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to push the local ref 'master' to the remote ref 'master' and
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the local `HEAD` to the remote 'branch', and the second
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asking to push ref 'foo' to ref 'bar' (forced update requested
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by the '+').
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+
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------------
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push refs/heads/master:refs/heads/master
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push HEAD:refs/heads/branch
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\n
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push +refs/heads/foo:refs/heads/bar
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\n
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------------
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+
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Zero or more protocol options may be entered after the last 'push'
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command, before the batch's terminating blank line.
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+
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When the push is complete, outputs one or more 'ok <dst>' or
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'error <dst> <why>?' lines to indicate success or failure of
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each pushed ref. The status report output is terminated by
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a blank line. The option field <why> may be quoted in a C
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style string if it contains an LF.
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+
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Supported if the helper has the "push" capability.
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'import' <name>::
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Produces a fast-import stream which imports the current value
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of the named ref. It may additionally import other refs as
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needed to construct the history efficiently. The script writes
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to a helper-specific private namespace. The value of the named
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ref should be written to a location in this namespace derived
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by applying the refspecs from the "refspec" capability to the
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name of the ref.
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+
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Especially useful for interoperability with a foreign versioning
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system.
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+
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Just like 'push', a batch sequence of one or more 'import' is
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terminated with a blank line. For each batch of 'import', the remote
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helper should produce a fast-import stream terminated by a 'done'
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command.
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+
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Note that if the 'bidi-import' capability is used the complete batch
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sequence has to be buffered before starting to send data to fast-import
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to prevent mixing of commands and fast-import responses on the helper's
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stdin.
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+
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Supported if the helper has the "import" capability.
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'export'::
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Instructs the remote helper that any subsequent input is
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part of a fast-import stream (generated by 'git fast-export')
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containing objects which should be pushed to the remote.
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+
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Especially useful for interoperability with a foreign versioning
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system.
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+
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The 'export-marks' and 'import-marks' capabilities, if specified,
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affect this command in so far as they are passed on to 'git
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fast-export', which then will load/store a table of marks for
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local objects. This can be used to implement for incremental
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operations.
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+
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Supported if the helper has the "export" capability.
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'connect' <service>::
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Connects to given service. Standard input and standard output
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of helper are connected to specified service (git prefix is
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included in service name so e.g. fetching uses 'git-upload-pack'
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as service) on remote side. Valid replies to this command are
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empty line (connection established), 'fallback' (no smart
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transport support, fall back to dumb transports) and just
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exiting with error message printed (can't connect, don't
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bother trying to fall back). After line feed terminating the
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positive (empty) response, the output of service starts. After
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the connection ends, the remote helper exits.
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+
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Supported if the helper has the "connect" capability.
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'stateless-connect' <service>::
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Experimental; for internal use only.
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Connects to the given remote service for communication using
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git's wire-protocol version 2. Valid replies to this command
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are empty line (connection established), 'fallback' (no smart
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transport support, fall back to dumb transports) and just
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exiting with error message printed (can't connect, don't bother
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trying to fall back). After line feed terminating the positive
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(empty) response, the output of the service starts. Messages
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(both request and response) must consist of zero or more
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PKT-LINEs, terminating in a flush packet. Response messages will
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then have a response end packet after the flush packet to
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indicate the end of a response. The client must not
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expect the server to store any state in between request-response
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pairs. After the connection ends, the remote helper exits.
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+
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Supported if the helper has the "stateless-connect" capability.
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'get' <uri> <path>::
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Downloads the file from the given `<uri>` to the given `<path>`. If
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`<path>.temp` exists, then Git assumes that the `.temp` file is a
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partial download from a previous attempt and will resume the
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download from that position.
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If a fatal error occurs, the program writes the error message to
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stderr and exits. The caller should expect that a suitable error
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message has been printed if the child closes the connection without
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completing a valid response for the current command.
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Additional commands may be supported, as may be determined from
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capabilities reported by the helper.
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REF LIST ATTRIBUTES
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-------------------
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The 'list' command produces a list of refs in which each ref
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may be followed by a list of attributes. The following ref list
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attributes are defined.
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'unchanged'::
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This ref is unchanged since the last import or fetch, although
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the helper cannot necessarily determine what value that produced.
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REF LIST KEYWORDS
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-----------------
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The 'list' command may produce a list of key-value pairs.
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The following keys are defined.
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'object-format'::
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The refs are using the given hash algorithm. This keyword is only
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used if the server and client both support the object-format
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extension.
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OPTIONS
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-------
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The following options are defined and (under suitable circumstances)
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set by Git if the remote helper has the 'option' capability.
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'option verbosity' <n>::
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Changes the verbosity of messages displayed by the helper.
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A value of 0 for <n> means that processes operate
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quietly, and the helper produces only error output.
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1 is the default level of verbosity, and higher values
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of <n> correspond to the number of -v flags passed on the
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command line.
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'option progress' {'true'|'false'}::
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Enables (or disables) progress messages displayed by the
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transport helper during a command.
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'option depth' <depth>::
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Deepens the history of a shallow repository.
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|
'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.
|
|
|
|
'option atomic' {'true'|'false'}::
|
|
When pushing, request the remote server to update refs in a single atomic
|
|
transaction. If successful, all refs will be updated, or none will. If the
|
|
remote side does not support this capability, the push will fail.
|
|
|
|
'option object-format' {'true'|algorithm}::
|
|
If 'true', indicate that the caller wants hash algorithm information
|
|
to be passed back from the remote. This mode is used when fetching
|
|
refs.
|
|
+
|
|
If set to an algorithm, indicate that the caller wants to interact with
|
|
the remote side using that algorithm.
|
|
|
|
SEE ALSO
|
|
--------
|
|
linkgit:git-remote[1]
|
|
|
|
linkgit:git-remote-ext[1]
|
|
|
|
linkgit:git-remote-fd[1]
|
|
|
|
linkgit:git-fast-import[1]
|
|
|
|
GIT
|
|
---
|
|
Part of the linkgit:git[1] suite
|