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