git-submodule.txt: quote usage in monospace, drop backslash
[git/git.git] / Documentation / gitremote-helpers.txt
1 gitremote-helpers(1)
2 ====================
3
4 NAME
5 ----
6 gitremote-helpers - Helper programs to interact with remote repositories
7
8 SYNOPSIS
9 --------
10 [verse]
11 'git remote-<transport>' <repository> [<URL>]
12
13 DESCRIPTION
14 -----------
15
16 Remote helper programs are normally not used directly by end users,
17 but they are invoked by Git when it needs to interact with remote
18 repositories Git does not support natively. A given helper will
19 implement a subset of the capabilities documented here. When Git
20 needs to interact with a repository using a remote helper, it spawns
21 the helper as an independent process, sends commands to the helper's
22 standard input, and expects results from the helper's standard
23 output. Because a remote helper runs as an independent process from
24 Git, there is no need to re-link Git to add a new helper, nor any
25 need to link the helper with the implementation of Git.
26
27 Every helper must support the "capabilities" command, which Git
28 uses to determine what other commands the helper will accept. Those
29 other commands can be used to discover and update remote refs,
30 transport objects between the object database and the remote repository,
31 and update the local object store.
32
33 Git comes with a "curl" family of remote helpers, that handle various
34 transport protocols, such as 'git-remote-http', 'git-remote-https',
35 'git-remote-ftp' and 'git-remote-ftps'. They implement the capabilities
36 'fetch', 'option', and 'push'.
37
38 INVOCATION
39 ----------
40
41 Remote helper programs are invoked with one or (optionally) two
42 arguments. The first argument specifies a remote repository as in Git;
43 it is either the name of a configured remote or a URL. The second
44 argument specifies a URL; it is usually of the form
45 '<transport>://<address>', but any arbitrary string is possible.
46 The `GIT_DIR` environment variable is set up for the remote helper
47 and can be used to determine where to store additional data or from
48 which directory to invoke auxiliary Git commands.
49
50 When Git encounters a URL of the form '<transport>://<address>', where
51 '<transport>' is a protocol that it cannot handle natively, it
52 automatically invokes 'git remote-<transport>' with the full URL as
53 the second argument. If such a URL is encountered directly on the
54 command line, the first argument is the same as the second, and if it
55 is encountered in a configured remote, the first argument is the name
56 of that remote.
57
58 A URL of the form '<transport>::<address>' explicitly instructs Git to
59 invoke 'git remote-<transport>' with '<address>' as the second
60 argument. If such a URL is encountered directly on the command line,
61 the first argument is '<address>', and if it is encountered in a
62 configured remote, the first argument is the name of that remote.
63
64 Additionally, when a configured remote has `remote.<name>.vcs` set to
65 '<transport>', Git explicitly invokes 'git remote-<transport>' with
66 '<name>' as the first argument. If set, the second argument is
67 `remote.<name>.url`; otherwise, the second argument is omitted.
68
69 INPUT FORMAT
70 ------------
71
72 Git sends the remote helper a list of commands on standard input, one
73 per line. The first command is always the 'capabilities' command, in
74 response to which the remote helper must print a list of the
75 capabilities it supports (see below) followed by a blank line. The
76 response to the capabilities command determines what commands Git uses
77 in the remainder of the command stream.
78
79 The command stream is terminated by a blank line. In some cases
80 (indicated in the documentation of the relevant commands), this blank
81 line is followed by a payload in some other protocol (e.g., the pack
82 protocol), while in others it indicates the end of input.
83
84 Capabilities
85 ~~~~~~~~~~~~
86
87 Each remote helper is expected to support only a subset of commands.
88 The operations a helper supports are declared to Git in the response
89 to the `capabilities` command (see COMMANDS, below).
90
91 In the following, we list all defined capabilities and for
92 each we list which commands a helper with that capability
93 must provide.
94
95 Capabilities for Pushing
96 ^^^^^^^^^^^^^^^^^^^^^^^^
97 'connect'::
98 Can attempt to connect to 'git receive-pack' (for pushing),
99 'git upload-pack', etc for communication using
100 git's native packfile protocol. This
101 requires a bidirectional, full-duplex connection.
102 +
103 Supported commands: 'connect'.
104
105 'push'::
106 Can discover remote refs and push local commits and the
107 history leading up to them to new or existing remote refs.
108 +
109 Supported commands: 'list for-push', 'push'.
110
111 'export'::
112 Can discover remote refs and push specified objects from a
113 fast-import stream to remote refs.
114 +
115 Supported commands: 'list for-push', 'export'.
116
117 If a helper advertises 'connect', Git will use it if possible and
118 fall back to another capability if the helper requests so when
119 connecting (see the 'connect' command under COMMANDS).
120 When choosing between 'push' and 'export', Git prefers 'push'.
121 Other frontends may have some other order of preference.
122
123 'no-private-update'::
124 When using the 'refspec' capability, git normally updates the
125 private ref on successful push. This update is disabled when
126 the remote-helper declares the capability 'no-private-update'.
127
128
129 Capabilities for Fetching
130 ^^^^^^^^^^^^^^^^^^^^^^^^^
131 'connect'::
132 Can try to connect to 'git upload-pack' (for fetching),
133 'git receive-pack', etc for communication using the
134 Git's native packfile protocol. This
135 requires a bidirectional, full-duplex connection.
136 +
137 Supported commands: 'connect'.
138
139 'fetch'::
140 Can discover remote refs and transfer objects reachable from
141 them to the local object store.
142 +
143 Supported commands: 'list', 'fetch'.
144
145 'import'::
146 Can discover remote refs and output objects reachable from
147 them as a stream in fast-import format.
148 +
149 Supported commands: 'list', 'import'.
150
151 'check-connectivity'::
152 Can guarantee that when a clone is requested, the received
153 pack is self contained and is connected.
154
155 If a helper advertises 'connect', Git will use it if possible and
156 fall back to another capability if the helper requests so when
157 connecting (see the 'connect' command under COMMANDS).
158 When choosing between 'fetch' and 'import', Git prefers 'fetch'.
159 Other frontends may have some other order of preference.
160
161 Miscellaneous capabilities
162 ^^^^^^^^^^^^^^^^^^^^^^^^^^
163
164 'option'::
165 For specifying settings like `verbosity` (how much output to
166 write to stderr) and `depth` (how much history is wanted in the
167 case of a shallow clone) that affect how other commands are
168 carried out.
169
170 'refspec' <refspec>::
171 For remote helpers that implement 'import' or 'export', this capability
172 allows the refs to be constrained to a private namespace, instead of
173 writing to refs/heads or refs/remotes directly.
174 It is recommended that all importers providing the 'import'
175 capability use this. It's mandatory for 'export'.
176 +
177 A helper advertising the capability
178 `refspec refs/heads/*:refs/svn/origin/branches/*`
179 is saying that, when it is asked to `import refs/heads/topic`, the
180 stream it outputs will update the `refs/svn/origin/branches/topic`
181 ref.
182 +
183 This capability can be advertised multiple times. The first
184 applicable refspec takes precedence. The left-hand of refspecs
185 advertised with this capability must cover all refs reported by
186 the list command. If no 'refspec' capability is advertised,
187 there is an implied `refspec *:*`.
188 +
189 When writing remote-helpers for decentralized version control
190 systems, it is advised to keep a local copy of the repository to
191 interact with, and to let the private namespace refs point to this
192 local repository, while the refs/remotes namespace is used to track
193 the remote repository.
194
195 'bidi-import'::
196 This modifies the 'import' capability.
197 The fast-import commands 'cat-blob' and 'ls' can be used by remote-helpers
198 to retrieve information about blobs and trees that already exist in
199 fast-import's memory. This requires a channel from fast-import to the
200 remote-helper.
201 If it is advertised in addition to "import", Git establishes a pipe from
202 fast-import to the remote-helper's stdin.
203 It follows that Git and fast-import are both connected to the
204 remote-helper's stdin. Because Git can send multiple commands to
205 the remote-helper it is required that helpers that use 'bidi-import'
206 buffer all 'import' commands of a batch before sending data to fast-import.
207 This is to prevent mixing commands and fast-import responses on the
208 helper's stdin.
209
210 'export-marks' <file>::
211 This modifies the 'export' capability, instructing Git to dump the
212 internal marks table to <file> when complete. For details,
213 read up on `--export-marks=<file>` in linkgit:git-fast-export[1].
214
215 'import-marks' <file>::
216 This modifies the 'export' capability, instructing Git to load the
217 marks specified in <file> before processing any input. For details,
218 read up on `--import-marks=<file>` in linkgit:git-fast-export[1].
219
220 'signed-tags'::
221 This modifies the 'export' capability, instructing Git to pass
222 `--signed-tags=verbatim` to linkgit:git-fast-export[1]. In the
223 absence of this capability, Git will use `--signed-tags=warn-strip`.
224
225
226
227 COMMANDS
228 --------
229
230 Commands are given by the caller on the helper's standard input, one per line.
231
232 'capabilities'::
233 Lists the capabilities of the helper, one per line, ending
234 with a blank line. Each capability may be preceded with '*',
235 which marks them mandatory for Git versions using the remote
236 helper to understand. Any unknown mandatory capability is a
237 fatal error.
238 +
239 Support for this command is mandatory.
240
241 'list'::
242 Lists the refs, one per line, in the format "<value> <name>
243 [<attr> ...]". The value may be a hex sha1 hash, "@<dest>" for
244 a symref, or "?" to indicate that the helper could not get the
245 value of the ref. A space-separated list of attributes follows
246 the name; unrecognized attributes are ignored. The list ends
247 with a blank line.
248 +
249 See REF LIST ATTRIBUTES for a list of currently defined attributes.
250 +
251 Supported if the helper has the "fetch" or "import" capability.
252
253 'list for-push'::
254 Similar to 'list', except that it is used if and only if
255 the caller wants to the resulting ref list to prepare
256 push commands.
257 A helper supporting both push and fetch can use this
258 to distinguish for which operation the output of 'list'
259 is going to be used, possibly reducing the amount
260 of work that needs to be performed.
261 +
262 Supported if the helper has the "push" or "export" capability.
263
264 'option' <name> <value>::
265 Sets the transport helper option <name> to <value>. Outputs a
266 single line containing one of 'ok' (option successfully set),
267 'unsupported' (option not recognized) or 'error <msg>'
268 (option <name> is supported but <value> is not valid
269 for it). Options should be set before other commands,
270 and may influence the behavior of those commands.
271 +
272 See OPTIONS for a list of currently defined options.
273 +
274 Supported if the helper has the "option" capability.
275
276 'fetch' <sha1> <name>::
277 Fetches the given object, writing the necessary objects
278 to the database. Fetch commands are sent in a batch, one
279 per line, terminated with a blank line.
280 Outputs a single blank line when all fetch commands in the
281 same batch are complete. Only objects which were reported
282 in the output of 'list' with a sha1 may be fetched this way.
283 +
284 Optionally may output a 'lock <file>' line indicating a file under
285 GIT_DIR/objects/pack which is keeping a pack until refs can be
286 suitably updated.
287 +
288 If option 'check-connectivity' is requested, the helper must output
289 'connectivity-ok' if the clone is self-contained and connected.
290 +
291 Supported if the helper has the "fetch" capability.
292
293 'push' +<src>:<dst>::
294 Pushes the given local <src> commit or branch to the
295 remote branch described by <dst>. A batch sequence of
296 one or more 'push' commands is terminated with a blank line
297 (if there is only one reference to push, a single 'push' command
298 is followed by a blank line). For example, the following would
299 be two batches of 'push', the first asking the remote-helper
300 to push the local ref 'master' to the remote ref 'master' and
301 the local `HEAD` to the remote 'branch', and the second
302 asking to push ref 'foo' to ref 'bar' (forced update requested
303 by the '+').
304 +
305 ------------
306 push refs/heads/master:refs/heads/master
307 push HEAD:refs/heads/branch
308 \n
309 push +refs/heads/foo:refs/heads/bar
310 \n
311 ------------
312 +
313 Zero or more protocol options may be entered after the last 'push'
314 command, before the batch's terminating blank line.
315 +
316 When the push is complete, outputs one or more 'ok <dst>' or
317 'error <dst> <why>?' lines to indicate success or failure of
318 each pushed ref. The status report output is terminated by
319 a blank line. The option field <why> may be quoted in a C
320 style string if it contains an LF.
321 +
322 Supported if the helper has the "push" capability.
323
324 'import' <name>::
325 Produces a fast-import stream which imports the current value
326 of the named ref. It may additionally import other refs as
327 needed to construct the history efficiently. The script writes
328 to a helper-specific private namespace. The value of the named
329 ref should be written to a location in this namespace derived
330 by applying the refspecs from the "refspec" capability to the
331 name of the ref.
332 +
333 Especially useful for interoperability with a foreign versioning
334 system.
335 +
336 Just like 'push', a batch sequence of one or more 'import' is
337 terminated with a blank line. For each batch of 'import', the remote
338 helper should produce a fast-import stream terminated by a 'done'
339 command.
340 +
341 Note that if the 'bidi-import' capability is used the complete batch
342 sequence has to be buffered before starting to send data to fast-import
343 to prevent mixing of commands and fast-import responses on the helper's
344 stdin.
345 +
346 Supported if the helper has the "import" capability.
347
348 'export'::
349 Instructs the remote helper that any subsequent input is
350 part of a fast-import stream (generated by 'git fast-export')
351 containing objects which should be pushed to the remote.
352 +
353 Especially useful for interoperability with a foreign versioning
354 system.
355 +
356 The 'export-marks' and 'import-marks' capabilities, if specified,
357 affect this command in so far as they are passed on to 'git
358 fast-export', which then will load/store a table of marks for
359 local objects. This can be used to implement for incremental
360 operations.
361 +
362 Supported if the helper has the "export" capability.
363
364 'connect' <service>::
365 Connects to given service. Standard input and standard output
366 of helper are connected to specified service (git prefix is
367 included in service name so e.g. fetching uses 'git-upload-pack'
368 as service) on remote side. Valid replies to this command are
369 empty line (connection established), 'fallback' (no smart
370 transport support, fall back to dumb transports) and just
371 exiting with error message printed (can't connect, don't
372 bother trying to fall back). After line feed terminating the
373 positive (empty) response, the output of service starts. After
374 the connection ends, the remote helper exits.
375 +
376 Supported if the helper has the "connect" capability.
377
378 If a fatal error occurs, the program writes the error message to
379 stderr and exits. The caller should expect that a suitable error
380 message has been printed if the child closes the connection without
381 completing a valid response for the current command.
382
383 Additional commands may be supported, as may be determined from
384 capabilities reported by the helper.
385
386 REF LIST ATTRIBUTES
387 -------------------
388
389 The 'list' command produces a list of refs in which each ref
390 may be followed by a list of attributes. The following ref list
391 attributes are defined.
392
393 'unchanged'::
394 This ref is unchanged since the last import or fetch, although
395 the helper cannot necessarily determine what value that produced.
396
397 OPTIONS
398 -------
399
400 The following options are defined and (under suitable circumstances)
401 set by Git if the remote helper has the 'option' capability.
402
403 'option verbosity' <n>::
404 Changes the verbosity of messages displayed by the helper.
405 A value of 0 for <n> means that processes operate
406 quietly, and the helper produces only error output.
407 1 is the default level of verbosity, and higher values
408 of <n> correspond to the number of -v flags passed on the
409 command line.
410
411 'option progress' {'true'|'false'}::
412 Enables (or disables) progress messages displayed by the
413 transport helper during a command.
414
415 'option depth' <depth>::
416 Deepens the history of a shallow repository.
417
418 'option deepen-since <timestamp>::
419 Deepens the history of a shallow repository based on time.
420
421 'option deepen-not <ref>::
422 Deepens the history of a shallow repository excluding ref.
423 Multiple options add up.
424
425 'option deepen-relative {'true'|'false'}::
426 Deepens the history of a shallow repository relative to
427 current boundary. Only valid when used with "option depth".
428
429 'option followtags' {'true'|'false'}::
430 If enabled the helper should automatically fetch annotated
431 tag objects if the object the tag points at was transferred
432 during the fetch command. If the tag is not fetched by
433 the helper a second fetch command will usually be sent to
434 ask for the tag specifically. Some helpers may be able to
435 use this option to avoid a second network connection.
436
437 'option dry-run' {'true'|'false'}:
438 If true, pretend the operation completed successfully,
439 but don't actually change any repository data. For most
440 helpers this only applies to the 'push', if supported.
441
442 'option servpath <c-style-quoted-path>'::
443 Sets service path (--upload-pack, --receive-pack etc.) for
444 next connect. Remote helper may support this option, but
445 must not rely on this option being set before
446 connect request occurs.
447
448 'option check-connectivity' {'true'|'false'}::
449 Request the helper to check connectivity of a clone.
450
451 'option force' {'true'|'false'}::
452 Request the helper to perform a force update. Defaults to
453 'false'.
454
455 'option cloning' {'true'|'false'}::
456 Notify the helper this is a clone request (i.e. the current
457 repository is guaranteed empty).
458
459 'option update-shallow' {'true'|'false'}::
460 Allow to extend .git/shallow if the new refs require it.
461
462 'option pushcert' {'true'|'false'}::
463 GPG sign pushes.
464
465 'option push-option <string>::
466 Transmit <string> as a push option. As the push option
467 must not contain LF or NUL characters, the string is not encoded.
468
469 'option from-promisor' {'true'|'false'}::
470 Indicate that these objects are being fetched from a promisor.
471
472 'option no-dependents' {'true'|'false'}::
473 Indicate that only the objects wanted need to be fetched, not
474 their dependents.
475
476 SEE ALSO
477 --------
478 linkgit:git-remote[1]
479
480 linkgit:git-remote-ext[1]
481
482 linkgit:git-remote-fd[1]
483
484 linkgit:git-remote-testgit[1]
485
486 linkgit:git-fast-import[1]
487
488 GIT
489 ---
490 Part of the linkgit:git[1] suite