6 git-remote-helpers - Helper programs to interact with remote repositories
11 'git remote-<transport>' <repository> [<URL>]
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.
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.
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'.
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.
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
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.
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.
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.
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.
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).
92 For specifying settings like `verbosity` (how much output to
93 write to stderr) and `depth` (how much history is wanted in the
94 case of a shallow clone) that affect how other commands are
98 For fetching and pushing using git's native packfile protocol
99 that requires a bidirectional, full-duplex connection.
102 For listing remote refs and pushing specified objects from the
103 local object store to remote refs.
106 For listing remote refs and fetching the associated history to
107 the local object store.
110 For listing remote refs and fetching the associated history as
111 a fast-import stream.
113 'refspec' <refspec>::
114 This modifies the 'import' capability, allowing the produced
115 fast-import stream to modify refs in a private namespace
116 instead of writing to refs/heads or refs/remotes directly.
117 It is recommended that all importers providing the 'import'
120 A helper advertising the capability
121 `refspec refs/heads/*:refs/svn/origin/branches/*`
122 is saying that, when it is asked to `import refs/heads/topic`, the
123 stream it outputs will update the `refs/svn/origin/branches/topic`
126 This capability can be advertised multiple times. The first
127 applicable refspec takes precedence. The left-hand of refspecs
128 advertised with this capability must cover all refs reported by
129 the list command. If no 'refspec' capability is advertised,
130 there is an implied `refspec *:*`.
133 The fast-import commands 'cat-blob' and 'ls' can be used by remote-helpers
134 to retrieve information about blobs and trees that already exist in
135 fast-import's memory. This requires a channel from fast-import to the
137 If it is advertised in addition to "import", git establishes a pipe from
138 fast-import to the remote-helper's stdin.
139 It follows that git and fast-import are both connected to the
140 remote-helper's stdin. Because git can send multiple commands to
141 the remote-helper it is required that helpers that use 'bidi-import'
142 buffer all 'import' commands of a batch before sending data to fast-import.
143 This is to prevent mixing commands and fast-import responses on the
146 Capabilities for Pushing
147 ~~~~~~~~~~~~~~~~~~~~~~~~
149 Can attempt to connect to 'git receive-pack' (for pushing),
150 'git upload-pack', etc for communication using the
153 Supported commands: 'connect'.
156 Can discover remote refs and push local commits and the
157 history leading up to them to new or existing remote refs.
159 Supported commands: 'list for-push', 'push'.
161 If a helper advertises both 'connect' and 'push', git will use
162 'connect' if possible and fall back to 'push' if the helper requests
163 so when connecting (see the 'connect' command under COMMANDS).
165 Capabilities for Fetching
166 ~~~~~~~~~~~~~~~~~~~~~~~~~
168 Can try to connect to 'git upload-pack' (for fetching),
169 'git receive-pack', etc for communication using the
172 Supported commands: 'connect'.
175 Can discover remote refs and transfer objects reachable from
176 them to the local object store.
178 Supported commands: 'list', 'fetch'.
181 Can discover remote refs and output objects reachable from
182 them as a stream in fast-import format.
184 Supported commands: 'list', 'import'.
186 If a helper advertises 'connect', git will use it if possible and
187 fall back to another capability if the helper requests so when
188 connecting (see the 'connect' command under COMMANDS).
189 When choosing between 'fetch' and 'import', git prefers 'fetch'.
190 Other frontends may have some other order of preference.
192 'refspec' <refspec>::
193 This modifies the 'import' capability.
196 `refspec refs/heads/*:refs/svn/origin/branches/*`
197 in its capabilities is saying that, when it handles
198 `import refs/heads/topic`, the stream it outputs will update the
199 `refs/svn/origin/branches/topic` ref.
201 This capability can be advertised multiple times. The first
202 applicable refspec takes precedence. The left-hand of refspecs
203 advertised with this capability must cover all refs reported by
204 the list command. If no 'refspec' capability is advertised,
205 there is an implied `refspec *:*`.
210 Commands are given by the caller on the helper's standard input, one per line.
213 Lists the capabilities of the helper, one per line, ending
214 with a blank line. Each capability may be preceded with '*',
215 which marks them mandatory for git version using the remote
216 helper to understand (unknown mandatory capability is fatal
220 Lists the refs, one per line, in the format "<value> <name>
221 [<attr> ...]". The value may be a hex sha1 hash, "@<dest>" for
222 a symref, or "?" to indicate that the helper could not get the
223 value of the ref. A space-separated list of attributes follows
224 the name; unrecognized attributes are ignored. The list ends
227 If 'push' is supported this may be called as 'list for-push'
228 to obtain the current refs prior to sending one or more 'push'
229 commands to the helper.
231 'option' <name> <value>::
232 Sets the transport helper option <name> to <value>. Outputs a
233 single line containing one of 'ok' (option successfully set),
234 'unsupported' (option not recognized) or 'error <msg>'
235 (option <name> is supported but <value> is not valid
236 for it). Options should be set before other commands,
237 and may influence the behavior of those commands.
239 Supported if the helper has the "option" capability.
241 'fetch' <sha1> <name>::
242 Fetches the given object, writing the necessary objects
243 to the database. Fetch commands are sent in a batch, one
244 per line, terminated with a blank line.
245 Outputs a single blank line when all fetch commands in the
246 same batch are complete. Only objects which were reported
247 in the ref list with a sha1 may be fetched this way.
249 Optionally may output a 'lock <file>' line indicating a file under
250 GIT_DIR/objects/pack which is keeping a pack until refs can be
253 Supported if the helper has the "fetch" capability.
255 'push' +<src>:<dst>::
256 Pushes the given local <src> commit or branch to the
257 remote branch described by <dst>. A batch sequence of
258 one or more 'push' commands is terminated with a blank line
259 (if there is only one reference to push, a single 'push' command
260 is followed by a blank line). For example, the following would
261 be two batches of 'push', the first asking the remote-helper
262 to push the local ref 'master' to the remote ref 'master' and
263 the local 'HEAD' to the remote 'branch', and the second
264 asking to push ref 'foo' to ref 'bar' (forced update requested
268 push refs/heads/master:refs/heads/master
269 push HEAD:refs/heads/branch
271 push +refs/heads/foo:refs/heads/bar
275 Zero or more protocol options may be entered after the last 'push'
276 command, before the batch's terminating blank line.
278 When the push is complete, outputs one or more 'ok <dst>' or
279 'error <dst> <why>?' lines to indicate success or failure of
280 each pushed ref. The status report output is terminated by
281 a blank line. The option field <why> may be quoted in a C
282 style string if it contains an LF.
284 Supported if the helper has the "push" capability.
287 Produces a fast-import stream which imports the current value
288 of the named ref. It may additionally import other refs as
289 needed to construct the history efficiently. The script writes
290 to a helper-specific private namespace. The value of the named
291 ref should be written to a location in this namespace derived
292 by applying the refspecs from the "refspec" capability to the
295 Especially useful for interoperability with a foreign versioning
298 Just like 'push', a batch sequence of one or more 'import' is
299 terminated with a blank line. For each batch of 'import', the remote
300 helper should produce a fast-import stream terminated by a 'done'
303 Note that if the 'bidi-import' capability is used the complete batch
304 sequence has to be buffered before starting to send data to fast-import
305 to prevent mixing of commands and fast-import responses on the helper's
308 Supported if the helper has the 'import' capability.
310 'connect' <service>::
311 Connects to given service. Standard input and standard output
312 of helper are connected to specified service (git prefix is
313 included in service name so e.g. fetching uses 'git-upload-pack'
314 as service) on remote side. Valid replies to this command are
315 empty line (connection established), 'fallback' (no smart
316 transport support, fall back to dumb transports) and just
317 exiting with error message printed (can't connect, don't
318 bother trying to fall back). After line feed terminating the
319 positive (empty) response, the output of service starts. After
320 the connection ends, the remote helper exits.
322 Supported if the helper has the "connect" capability.
324 If a fatal error occurs, the program writes the error message to
325 stderr and exits. The caller should expect that a suitable error
326 message has been printed if the child closes the connection without
327 completing a valid response for the current command.
329 Additional commands may be supported, as may be determined from
330 capabilities reported by the helper.
336 The caller wants to use the ref list to prepare push
337 commands. A helper might chose to acquire the ref list by
338 opening a different type of connection to the destination.
341 This ref is unchanged since the last import or fetch, although
342 the helper cannot necessarily determine what value that produced.
346 'option verbosity' <n>::
347 Changes the verbosity of messages displayed by the helper.
348 A value of 0 for <n> means that processes operate
349 quietly, and the helper produces only error output.
350 1 is the default level of verbosity, and higher values
351 of <n> correspond to the number of -v flags passed on the
354 'option progress' \{'true'|'false'\}::
355 Enables (or disables) progress messages displayed by the
356 transport helper during a command.
358 'option depth' <depth>::
359 Deepens the history of a shallow repository.
361 'option followtags' \{'true'|'false'\}::
362 If enabled the helper should automatically fetch annotated
363 tag objects if the object the tag points at was transferred
364 during the fetch command. If the tag is not fetched by
365 the helper a second fetch command will usually be sent to
366 ask for the tag specifically. Some helpers may be able to
367 use this option to avoid a second network connection.
369 'option dry-run' \{'true'|'false'\}:
370 If true, pretend the operation completed successfully,
371 but don't actually change any repository data. For most
372 helpers this only applies to the 'push', if supported.
374 'option servpath <c-style-quoted-path>'::
375 Sets service path (--upload-pack, --receive-pack etc.) for
376 next connect. Remote helper may support this option, but
377 must not rely on this option being set before
378 connect request occurs.
382 linkgit:git-remote[1]
384 linkgit:git-remote-testgit[1]
388 Part of the linkgit:git[1] suite