2 .\" Title: gitremote-helpers
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10 .TH "GITREMOTE\-HELPERS" "7" "04/25/2023" "Git 2\&.40\&.1\&.423\&.g2807bd" "Git Manual"
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31 gitremote-helpers \- Helper programs to interact with remote repositories
35 \fIgit remote\-<transport>\fR <repository> [<URL>]
40 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\(cqs standard input, and expects results from the helper\(cqs 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\&.
42 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\&.
44 Git comes with a "curl" family of remote helpers, that handle various transport protocols, such as \fIgit\-remote\-http\fR, \fIgit\-remote\-https\fR, \fIgit\-remote\-ftp\fR and \fIgit\-remote\-ftps\fR\&. They implement the capabilities \fIfetch\fR, \fIoption\fR, and \fIpush\fR\&.
47 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 \fI<transport>://<address>\fR, but any arbitrary string is possible\&. The \fBGIT_DIR\fR 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\&.
49 When Git encounters a URL of the form \fI<transport>://<address>\fR, where \fI<transport>\fR is a protocol that it cannot handle natively, it automatically invokes \fIgit remote\-<transport>\fR 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\&.
51 A URL of the form \fI<transport>::<address>\fR explicitly instructs Git to invoke \fIgit remote\-<transport>\fR with \fI<address>\fR as the second argument\&. If such a URL is encountered directly on the command line, the first argument is \fI<address>\fR, and if it is encountered in a configured remote, the first argument is the name of that remote\&.
53 Additionally, when a configured remote has \fBremote\&.<name>\&.vcs\fR set to \fI<transport>\fR, Git explicitly invokes \fIgit remote\-<transport>\fR with \fI<name>\fR as the first argument\&. If set, the second argument is \fBremote\&.<name>\&.url\fR; otherwise, the second argument is omitted\&.
56 Git sends the remote helper a list of commands on standard input, one per line\&. The first command is always the \fIcapabilities\fR 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\&.
58 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\&.
61 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 \fBcapabilities\fR command (see COMMANDS, below)\&.
63 In the following, we list all defined capabilities and for each we list which commands a helper with that capability must provide\&.
66 .nr an-no-space-flag 1
70 \fBCapabilities for Pushing\fR
75 Can attempt to connect to
76 \fIgit receive\-pack\fR
78 \fIgit upload\-pack\fR, etc for communication using git\(cqs native packfile protocol\&. This requires a bidirectional, full\-duplex connection\&.
84 \fIstateless\-connect\fR
86 Experimental; for internal use only\&. Can attempt to connect to a remote server for communication using git\(cqs wire\-protocol version 2\&. See the documentation for the stateless\-connect command for more information\&.
89 \fIstateless\-connect\fR\&.
94 Can discover remote refs and push local commits and the history leading up to them to new or existing remote refs\&.
103 Can discover remote refs and push specified objects from a fast\-import stream to remote refs\&.
106 \fIlist for\-push\fR,
110 If a helper advertises \fIconnect\fR, Git will use it if possible and fall back to another capability if the helper requests so when connecting (see the \fIconnect\fR command under COMMANDS)\&. When choosing between \fIpush\fR and \fIexport\fR, Git prefers \fIpush\fR\&. Other frontends may have some other order of preference\&.
112 \fIno\-private\-update\fR
116 capability, git normally updates the private ref on successful push\&. This update is disabled when the remote\-helper declares the capability
117 \fIno\-private\-update\fR\&.
122 .nr an-no-space-flag 1
126 \fBCapabilities for Fetching\fR
131 Can try to connect to
132 \fIgit upload\-pack\fR
134 \fIgit receive\-pack\fR, etc for communication using the Git\(cqs native packfile protocol\&. This requires a bidirectional, full\-duplex connection\&.
140 \fIstateless\-connect\fR
142 Experimental; for internal use only\&. Can attempt to connect to a remote server for communication using git\(cqs wire\-protocol version 2\&. See the documentation for the stateless\-connect command for more information\&.
145 \fIstateless\-connect\fR\&.
150 Can discover remote refs and transfer objects reachable from them to the local object store\&.
159 Can discover remote refs and output objects reachable from them as a stream in fast\-import format\&.
166 \fIcheck\-connectivity\fR
168 Can guarantee that when a clone is requested, the received pack is self contained and is connected\&.
175 command to download a file from a given URI\&.
178 If a helper advertises \fIconnect\fR, Git will use it if possible and fall back to another capability if the helper requests so when connecting (see the \fIconnect\fR command under COMMANDS)\&. When choosing between \fIfetch\fR and \fIimport\fR, Git prefers \fIfetch\fR\&. Other frontends may have some other order of preference\&.
182 .nr an-no-space-flag 1
186 \fBMiscellaneous capabilities\fR
191 For specifying settings like
193 (how much output to write to stderr) and
195 (how much history is wanted in the case of a shallow clone) that affect how other commands are carried out\&.
198 \fIrefspec\fR <refspec>
200 For remote helpers that implement
203 \fIexport\fR, 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
205 capability use this\&. It\(cqs mandatory for
208 A helper advertising the capability
209 \fBrefspec refs/heads/*:refs/svn/origin/branches/*\fR
210 is saying that, when it is asked to
211 \fBimport refs/heads/topic\fR, the stream it outputs will update the
212 \fBrefs/svn/origin/branches/topic\fR
215 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
217 capability is advertised, there is an implied
220 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\&.
227 capability\&. The fast\-import commands
231 can be used by remote\-helpers to retrieve information about blobs and trees that already exist in fast\-import\(cqs 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\(cqs stdin\&. It follows that Git and fast\-import are both connected to the remote\-helper\(cqs stdin\&. Because Git can send multiple commands to the remote\-helper it is required that helpers that use
235 commands of a batch before sending data to fast\-import\&. This is to prevent mixing commands and fast\-import responses on the helper\(cqs stdin\&.
238 \fIexport\-marks\fR <file>
242 capability, instructing Git to dump the internal marks table to <file> when complete\&. For details, read up on
243 \fB\-\-export\-marks=<file>\fR
245 \fBgit-fast-export\fR(1)\&.
248 \fIimport\-marks\fR <file>
252 capability, instructing Git to load the marks specified in <file> before processing any input\&. For details, read up on
253 \fB\-\-import\-marks=<file>\fR
255 \fBgit-fast-export\fR(1)\&.
262 capability, instructing Git to pass
263 \fB\-\-signed\-tags=verbatim\fR
265 \fBgit-fast-export\fR(1)\&. In the absence of this capability, Git will use
266 \fB\-\-signed\-tags=warn\-strip\fR\&.
271 This indicates that the helper is able to interact with the remote side using an explicit hash algorithm extension\&.
276 Commands are given by the caller on the helper\(cqs standard input, one per line\&.
280 Lists the capabilities of the helper, one per line, ending with a blank line\&. Each capability may be preceded with
281 \fI*\fR, which marks them mandatory for Git versions using the remote helper to understand\&. Any unknown mandatory capability is a fatal error\&.
283 Support for this command is mandatory\&.
288 Lists the refs, one per line, in the format "<value> <name> [<attr> \&...]"\&. The value may be a hex sha1 hash, "@<dest>" for a symref, ":<keyword> <value>" for a key\-value pair, 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\&.
290 See REF LIST ATTRIBUTES for a list of currently defined attributes\&. See REF LIST KEYWORDS for a list of currently defined keywords\&.
292 Supported if the helper has the "fetch" or "import" capability\&.
298 \fIlist\fR, 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
300 is going to be used, possibly reducing the amount of work that needs to be performed\&.
302 Supported if the helper has the "push" or "export" capability\&.
305 \fIoption\fR <name> <value>
307 Sets the transport helper option <name> to <value>\&. Outputs a single line containing one of
309 (option successfully set),
311 (option not recognized) or
313 (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\&.
315 See OPTIONS for a list of currently defined options\&.
317 Supported if the helper has the "option" capability\&.
320 \fIfetch\fR <sha1> <name>
322 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
324 with a sha1 may be fetched this way\&.
326 Optionally may output a
328 line indicating the full path of a file under
329 \fB$GIT_DIR/objects/pack\fR
330 which is keeping a pack until refs can be suitably updated\&. The path must end with
331 \fB\&.keep\fR\&. 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
333 file will be deleted at the conclusion of the fetch\&.
336 \fIcheck\-connectivity\fR
337 is requested, the helper must output
338 \fIconnectivity\-ok\fR
339 if the clone is self\-contained and connected\&.
341 Supported if the helper has the "fetch" capability\&.
344 \fIpush\fR +<src>:<dst>
346 Pushes the given local <src> commit or branch to the remote branch described by <dst>\&. A batch sequence of one or more
348 commands is terminated with a blank line (if there is only one reference to push, a single
350 command is followed by a blank line)\&. For example, the following would be two batches of
351 \fIpush\fR, the first asking the remote\-helper to push the local ref
358 \fIbranch\fR, and the second asking to push ref
362 (forced update requested by the
369 push refs/heads/master:refs/heads/master
370 push HEAD:refs/heads/branch
372 push +refs/heads/foo:refs/heads/bar
379 Zero or more protocol options may be entered after the last
381 command, before the batch\(cqs terminating blank line\&.
383 When the push is complete, outputs one or more
386 \fIerror <dst> <why>?\fR
387 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\&.
389 Supported if the helper has the "push" capability\&.
394 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\&.
396 Especially useful for interoperability with a foreign versioning system\&.
399 \fIpush\fR, a batch sequence of one or more
401 is terminated with a blank line\&. For each batch of
402 \fIimport\fR, the remote helper should produce a fast\-import stream terminated by a
408 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\(cqs stdin\&.
410 Supported if the helper has the "import" capability\&.
415 Instructs the remote helper that any subsequent input is part of a fast\-import stream (generated by
416 \fIgit fast\-export\fR) containing objects which should be pushed to the remote\&.
418 Especially useful for interoperability with a foreign versioning system\&.
424 capabilities, if specified, affect this command in so far as they are passed on to
425 \fIgit fast\-export\fR, which then will load/store a table of marks for local objects\&. This can be used to implement for incremental operations\&.
427 Supported if the helper has the "export" capability\&.
430 \fIconnect\fR <service>
432 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
433 \fIgit\-upload\-pack\fR
434 as service) on remote side\&. Valid replies to this command are empty line (connection established),
436 (no smart transport support, fall back to dumb transports) and just exiting with error message printed (can\(cqt connect, don\(cqt 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\&.
438 Supported if the helper has the "connect" capability\&.
441 \fIstateless\-connect\fR <service>
443 Experimental; for internal use only\&. Connects to the given remote service for communication using git\(cqs wire\-protocol version 2\&. Valid replies to this command are empty line (connection established),
445 (no smart transport support, fall back to dumb transports) and just exiting with error message printed (can\(cqt connect, don\(cqt 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\&. Response messages will then have a response end packet after the flush packet to indicate the end of a response\&. The client must not expect the server to store any state in between request\-response pairs\&. After the connection ends, the remote helper exits\&.
447 Supported if the helper has the "stateless\-connect" capability\&.
450 \fIget\fR <uri> <path>
452 Downloads the file from the given
457 exists, then Git assumes that the
459 file is a partial download from a previous attempt and will resume the download from that position\&.
462 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\&.
464 Additional commands may be supported, as may be determined from capabilities reported by the helper\&.
465 .SH "REF LIST ATTRIBUTES"
467 The \fIlist\fR 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\&.
471 This ref is unchanged since the last import or fetch, although the helper cannot necessarily determine what value that produced\&.
473 .SH "REF LIST KEYWORDS"
475 The \fIlist\fR command may produce a list of key\-value pairs\&. The following keys are defined\&.
479 The refs are using the given hash algorithm\&. This keyword is only used if the server and client both support the object\-format extension\&.
483 The following options are defined and (under suitable circumstances) set by Git if the remote helper has the \fIoption\fR capability\&.
485 \fIoption verbosity\fR <n>
487 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\&.
490 \fIoption progress\fR {\fItrue\fR|\fIfalse\fR}
492 Enables (or disables) progress messages displayed by the transport helper during a command\&.
495 \fIoption depth\fR <depth>
497 Deepens the history of a shallow repository\&.
500 \*(Aqoption deepen\-since <timestamp>
502 Deepens the history of a shallow repository based on time\&.
505 \*(Aqoption deepen\-not <ref>
507 Deepens the history of a shallow repository excluding ref\&. Multiple options add up\&.
510 \fIoption deepen\-relative {\*(Aqtrue\fR|\fIfalse\fR}
512 Deepens the history of a shallow repository relative to current boundary\&. Only valid when used with "option depth"\&.
515 \fIoption followtags\fR {\fItrue\fR|\fIfalse\fR}
517 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\&.
520 \fIoption dry\-run\fR {\fItrue\fR|\fIfalse\fR}: If true, pretend the operation completed successfully, but don\(cqt actually change any repository data\&. For most helpers this only applies to the \fIpush\fR, if supported\&.
522 \fIoption servpath <c\-style\-quoted\-path>\fR
524 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\&.
527 \fIoption check\-connectivity\fR {\fItrue\fR|\fIfalse\fR}
529 Request the helper to check connectivity of a clone\&.
532 \fIoption force\fR {\fItrue\fR|\fIfalse\fR}
534 Request the helper to perform a force update\&. Defaults to
538 \fIoption cloning\fR {\fItrue\fR|\fIfalse\fR}
540 Notify the helper this is a clone request (i\&.e\&. the current repository is guaranteed empty)\&.
543 \fIoption update\-shallow\fR {\fItrue\fR|\fIfalse\fR}
545 Allow to extend \&.git/shallow if the new refs require it\&.
548 \fIoption pushcert\fR {\fItrue\fR|\fIfalse\fR}
553 \*(Aqoption push\-option <string>
555 Transmit <string> as a push option\&. As the push option must not contain LF or NUL characters, the string is not encoded\&.
558 \fIoption from\-promisor\fR {\fItrue\fR|\fIfalse\fR}
560 Indicate that these objects are being fetched from a promisor\&.
563 \fIoption no\-dependents\fR {\fItrue\fR|\fIfalse\fR}
565 Indicate that only the objects wanted need to be fetched, not their dependents\&.
568 \fIoption atomic\fR {\fItrue\fR|\fIfalse\fR}
570 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\&.
573 \fIoption object\-format\fR {\fItrue\fR|algorithm}
576 \fItrue\fR, indicate that the caller wants hash algorithm information to be passed back from the remote\&. This mode is used when fetching refs\&.
578 If set to an algorithm, indicate that the caller wants to interact with the remote side using that algorithm\&.
584 \fBgit-remote-ext\fR(1)
586 \fBgit-remote-fd\fR(1)
588 \fBgit-fast-import\fR(1)
591 Part of the \fBgit\fR(1) suite