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1 | @c -*-texinfo-*- |
2 | @c This is part of the GNU Emacs Lisp Reference Manual. | |
fd897522 | 3 | @c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999 |
177c0ea7 | 4 | @c Free Software Foundation, Inc. |
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5 | @c See the file elisp.texi for copying conditions. |
6 | @setfilename ../info/processes | |
969fe9b5 | 7 | @node Processes, Display, Abbrevs, Top |
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8 | @chapter Processes |
9 | @cindex child process | |
10 | @cindex parent process | |
11 | @cindex subprocess | |
12 | @cindex process | |
13 | ||
14 | In the terminology of operating systems, a @dfn{process} is a space in | |
15 | which a program can execute. Emacs runs in a process. Emacs Lisp | |
16 | programs can invoke other programs in processes of their own. These are | |
17 | called @dfn{subprocesses} or @dfn{child processes} of the Emacs process, | |
18 | which is their @dfn{parent process}. | |
19 | ||
20 | A subprocess of Emacs may be @dfn{synchronous} or @dfn{asynchronous}, | |
21 | depending on how it is created. When you create a synchronous | |
22 | subprocess, the Lisp program waits for the subprocess to terminate | |
23 | before continuing execution. When you create an asynchronous | |
24 | subprocess, it can run in parallel with the Lisp program. This kind of | |
25 | subprocess is represented within Emacs by a Lisp object which is also | |
26 | called a ``process''. Lisp programs can use this object to communicate | |
27 | with the subprocess or to control it. For example, you can send | |
28 | signals, obtain status information, receive output from the process, or | |
29 | send input to it. | |
30 | ||
31 | @defun processp object | |
32 | This function returns @code{t} if @var{object} is a process, | |
33 | @code{nil} otherwise. | |
34 | @end defun | |
35 | ||
36 | @menu | |
37 | * Subprocess Creation:: Functions that start subprocesses. | |
a9f0a989 | 38 | * Shell Arguments:: Quoting an argument to pass it to a shell. |
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39 | * Synchronous Processes:: Details of using synchronous subprocesses. |
40 | * Asynchronous Processes:: Starting up an asynchronous subprocess. | |
41 | * Deleting Processes:: Eliminating an asynchronous subprocess. | |
42 | * Process Information:: Accessing run-status and other attributes. | |
43 | * Input to Processes:: Sending input to an asynchronous subprocess. | |
44 | * Signals to Processes:: Stopping, continuing or interrupting | |
45 | an asynchronous subprocess. | |
46 | * Output from Processes:: Collecting output from an asynchronous subprocess. | |
47 | * Sentinels:: Sentinels run when process run-status changes. | |
edc590bb | 48 | * Query Before Exit:: Whether to query if exiting will kill a process. |
73804d4b | 49 | * Transaction Queues:: Transaction-based communication with subprocesses. |
bfe721d1 | 50 | * Network:: Opening network connections. |
4bb24054 RS |
51 | * Network Servers:: Network servers let Emacs accept net connections. |
52 | * Datagrams:: | |
53 | * Low-Level Network:: Lower-level but more general function | |
54 | to create connections and servers. | |
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55 | @end menu |
56 | ||
57 | @node Subprocess Creation | |
58 | @section Functions that Create Subprocesses | |
59 | ||
60 | There are three functions that create a new subprocess in which to run | |
61 | a program. One of them, @code{start-process}, creates an asynchronous | |
62 | process and returns a process object (@pxref{Asynchronous Processes}). | |
63 | The other two, @code{call-process} and @code{call-process-region}, | |
64 | create a synchronous process and do not return a process object | |
65 | (@pxref{Synchronous Processes}). | |
66 | ||
8241495d | 67 | Synchronous and asynchronous processes are explained in the following |
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68 | sections. Since the three functions are all called in a similar |
69 | fashion, their common arguments are described here. | |
70 | ||
71 | @cindex execute program | |
72 | @cindex @code{PATH} environment variable | |
73 | @cindex @code{HOME} environment variable | |
74 | In all cases, the function's @var{program} argument specifies the | |
75 | program to be run. An error is signaled if the file is not found or | |
76 | cannot be executed. If the file name is relative, the variable | |
77 | @code{exec-path} contains a list of directories to search. Emacs | |
78 | initializes @code{exec-path} when it starts up, based on the value of | |
79 | the environment variable @code{PATH}. The standard file name | |
fea5a6d5 RS |
80 | constructs, @samp{~}, @samp{.}, and @samp{..}, are interpreted as |
81 | usual in @code{exec-path}, but environment variable substitutions | |
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82 | (@samp{$HOME}, etc.) are not recognized; use |
83 | @code{substitute-in-file-name} to perform them (@pxref{File Name | |
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84 | Expansion}). @code{nil} in this list refers to |
85 | @code{default-directory}. | |
73804d4b | 86 | |
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87 | Executing a program can also try adding suffixes to the specified |
88 | name: | |
89 | ||
90 | @defvar exec-suffixes | |
91 | This variable is a list of suffixes (strings) to try adding to the | |
92 | specified program file name. The list should include @code{""} if you | |
93 | want the name to be tried exactly as specified. The default value is | |
94 | system-dependent. | |
95 | @end defvar | |
96 | ||
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97 | @strong{Please note:} The argument @var{program} contains only the |
98 | name of the program; it may not contain any command-line arguments. You | |
99 | must use @var{args} to provide those. | |
100 | ||
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101 | Each of the subprocess-creating functions has a @var{buffer-or-name} |
102 | argument which specifies where the standard output from the program will | |
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103 | go. It should be a buffer or a buffer name; if it is a buffer name, |
104 | that will create the buffer if it does not already exist. It can also | |
105 | be @code{nil}, which says to discard the output unless a filter function | |
106 | handles it. (@xref{Filter Functions}, and @ref{Read and Print}.) | |
107 | Normally, you should avoid having multiple processes send output to the | |
108 | same buffer because their output would be intermixed randomly. | |
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109 | |
110 | @cindex program arguments | |
111 | All three of the subprocess-creating functions have a @code{&rest} | |
112 | argument, @var{args}. The @var{args} must all be strings, and they are | |
113 | supplied to @var{program} as separate command line arguments. Wildcard | |
f9f59935 | 114 | characters and other shell constructs have no special meanings in these |
fea5a6d5 | 115 | strings, since the strings are passed directly to the specified program. |
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116 | |
117 | The subprocess gets its current directory from the value of | |
118 | @code{default-directory} (@pxref{File Name Expansion}). | |
119 | ||
120 | @cindex environment variables, subprocesses | |
1911e6e5 | 121 | The subprocess inherits its environment from Emacs, but you can |
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122 | specify overrides for it with @code{process-environment}. @xref{System |
123 | Environment}. | |
124 | ||
177c0ea7 | 125 | @defvar exec-directory |
a9042418 | 126 | @pindex movemail |
8241495d | 127 | The value of this variable is a string, the name of a directory that |
1911e6e5 | 128 | contains programs that come with GNU Emacs, programs intended for Emacs |
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129 | to invoke. The program @code{movemail} is an example of such a program; |
130 | Rmail uses it to fetch new mail from an inbox. | |
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131 | @end defvar |
132 | ||
133 | @defopt exec-path | |
134 | The value of this variable is a list of directories to search for | |
135 | programs to run in subprocesses. Each element is either the name of a | |
136 | directory (i.e., a string), or @code{nil}, which stands for the default | |
137 | directory (which is the value of @code{default-directory}). | |
138 | @cindex program directories | |
139 | ||
140 | The value of @code{exec-path} is used by @code{call-process} and | |
141 | @code{start-process} when the @var{program} argument is not an absolute | |
142 | file name. | |
143 | @end defopt | |
144 | ||
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145 | @node Shell Arguments |
146 | @section Shell Arguments | |
147 | ||
148 | Lisp programs sometimes need to run a shell and give it a command | |
8241495d | 149 | that contains file names that were specified by the user. These |
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150 | programs ought to be able to support any valid file name. But the shell |
151 | gives special treatment to certain characters, and if these characters | |
152 | occur in the file name, they will confuse the shell. To handle these | |
153 | characters, use the function @code{shell-quote-argument}: | |
154 | ||
155 | @defun shell-quote-argument argument | |
156 | This function returns a string which represents, in shell syntax, | |
157 | an argument whose actual contents are @var{argument}. It should | |
158 | work reliably to concatenate the return value into a shell command | |
159 | and then pass it to a shell for execution. | |
160 | ||
161 | Precisely what this function does depends on your operating system. The | |
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162 | function is designed to work with the syntax of your system's standard |
163 | shell; if you use an unusual shell, you will need to redefine this | |
164 | function. | |
969fe9b5 RS |
165 | |
166 | @example | |
167 | ;; @r{This example shows the behavior on GNU and Unix systems.} | |
168 | (shell-quote-argument "foo > bar") | |
169 | @result{} "foo\\ \\>\\ bar" | |
8241495d RS |
170 | |
171 | ;; @r{This example shows the behavior on MS-DOS and MS-Windows systems.} | |
172 | (shell-quote-argument "foo > bar") | |
173 | @result{} "\"foo > bar\"" | |
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174 | @end example |
175 | ||
176 | Here's an example of using @code{shell-quote-argument} to construct | |
177 | a shell command: | |
178 | ||
179 | @example | |
180 | (concat "diff -c " | |
181 | (shell-quote-argument oldfile) | |
182 | " " | |
183 | (shell-quote-argument newfile)) | |
184 | @end example | |
185 | @end defun | |
186 | ||
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187 | @node Synchronous Processes |
188 | @section Creating a Synchronous Process | |
189 | @cindex synchronous subprocess | |
190 | ||
191 | After a @dfn{synchronous process} is created, Emacs waits for the | |
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192 | process to terminate before continuing. Starting Dired on GNU or |
193 | Unix@footnote{On other systems, Emacs uses a Lisp emulation of | |
194 | @code{ls}; see @ref{Contents of Directories}.} is an example of this: it | |
195 | runs @code{ls} in a synchronous process, then modifies the output | |
196 | slightly. Because the process is synchronous, the entire directory | |
197 | listing arrives in the buffer before Emacs tries to do anything with it. | |
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198 | |
199 | While Emacs waits for the synchronous subprocess to terminate, the | |
200 | user can quit by typing @kbd{C-g}. The first @kbd{C-g} tries to kill | |
201 | the subprocess with a @code{SIGINT} signal; but it waits until the | |
202 | subprocess actually terminates before quitting. If during that time the | |
203 | user types another @kbd{C-g}, that kills the subprocess instantly with | |
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204 | @code{SIGKILL} and quits immediately (except on MS-DOS, where killing |
205 | other processes doesn't work). @xref{Quitting}. | |
73804d4b | 206 | |
969fe9b5 RS |
207 | The synchronous subprocess functions return an indication of how the |
208 | process terminated. | |
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209 | |
210 | The output from a synchronous subprocess is generally decoded using a | |
211 | coding system, much like text read from a file. The input sent to a | |
212 | subprocess by @code{call-process-region} is encoded using a coding | |
213 | system, much like text written into a file. @xref{Coding Systems}. | |
73804d4b | 214 | |
22697dac | 215 | @defun call-process program &optional infile destination display &rest args |
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216 | This function calls @var{program} in a separate process and waits for |
217 | it to finish. | |
218 | ||
219 | The standard input for the process comes from file @var{infile} if | |
8241495d | 220 | @var{infile} is not @code{nil}, and from the null device otherwise. |
22697dac KH |
221 | The argument @var{destination} says where to put the process output. |
222 | Here are the possibilities: | |
223 | ||
224 | @table @asis | |
225 | @item a buffer | |
226 | Insert the output in that buffer, before point. This includes both the | |
227 | standard output stream and the standard error stream of the process. | |
228 | ||
229 | @item a string | |
969fe9b5 | 230 | Insert the output in a buffer with that name, before point. |
22697dac KH |
231 | |
232 | @item @code{t} | |
233 | Insert the output in the current buffer, before point. | |
234 | ||
235 | @item @code{nil} | |
236 | Discard the output. | |
237 | ||
238 | @item 0 | |
8241495d | 239 | Discard the output, and return @code{nil} immediately without waiting |
22697dac KH |
240 | for the subprocess to finish. |
241 | ||
242 | In this case, the process is not truly synchronous, since it can run in | |
243 | parallel with Emacs; but you can think of it as synchronous in that | |
244 | Emacs is essentially finished with the subprocess as soon as this | |
245 | function returns. | |
246 | ||
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247 | MS-DOS doesn't support asynchronous subprocesses, so this option doesn't |
248 | work there. | |
249 | ||
1911e6e5 | 250 | @item @code{(@var{real-destination} @var{error-destination})} |
22697dac KH |
251 | Keep the standard output stream separate from the standard error stream; |
252 | deal with the ordinary output as specified by @var{real-destination}, | |
253 | and dispose of the error output according to @var{error-destination}. | |
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254 | If @var{error-destination} is @code{nil}, that means to discard the |
255 | error output, @code{t} means mix it with the ordinary output, and a | |
256 | string specifies a file name to redirect error output into. | |
22697dac KH |
257 | |
258 | You can't directly specify a buffer to put the error output in; that is | |
259 | too difficult to implement. But you can achieve this result by sending | |
260 | the error output to a temporary file and then inserting the file into a | |
261 | buffer. | |
262 | @end table | |
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263 | |
264 | If @var{display} is non-@code{nil}, then @code{call-process} redisplays | |
a9f0a989 RS |
265 | the buffer as output is inserted. (However, if the coding system chosen |
266 | for decoding output is @code{undecided}, meaning deduce the encoding | |
267 | from the actual data, then redisplay sometimes cannot continue once | |
ad800164 | 268 | non-@acronym{ASCII} characters are encountered. There are fundamental |
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269 | reasons why it is hard to fix this; see @ref{Output from Processes}.) |
270 | ||
271 | Otherwise the function @code{call-process} does no redisplay, and the | |
272 | results become visible on the screen only when Emacs redisplays that | |
273 | buffer in the normal course of events. | |
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274 | |
275 | The remaining arguments, @var{args}, are strings that specify command | |
276 | line arguments for the program. | |
277 | ||
278 | The value returned by @code{call-process} (unless you told it not to | |
279 | wait) indicates the reason for process termination. A number gives the | |
280 | exit status of the subprocess; 0 means success, and any other value | |
281 | means failure. If the process terminated with a signal, | |
282 | @code{call-process} returns a string describing the signal. | |
283 | ||
284 | In the examples below, the buffer @samp{foo} is current. | |
285 | ||
286 | @smallexample | |
287 | @group | |
288 | (call-process "pwd" nil t) | |
8241495d | 289 | @result{} 0 |
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290 | |
291 | ---------- Buffer: foo ---------- | |
292 | /usr/user/lewis/manual | |
293 | ---------- Buffer: foo ---------- | |
294 | @end group | |
295 | ||
296 | @group | |
297 | (call-process "grep" nil "bar" nil "lewis" "/etc/passwd") | |
8241495d | 298 | @result{} 0 |
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299 | |
300 | ---------- Buffer: bar ---------- | |
301 | lewis:5LTsHm66CSWKg:398:21:Bil Lewis:/user/lewis:/bin/csh | |
302 | ||
303 | ---------- Buffer: bar ---------- | |
304 | @end group | |
305 | @end smallexample | |
306 | ||
969fe9b5 RS |
307 | Here is a good example of the use of @code{call-process}, which used to |
308 | be found in the definition of @code{insert-directory}: | |
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309 | |
310 | @smallexample | |
311 | @group | |
969fe9b5 | 312 | (call-process insert-directory-program nil t nil @var{switches} |
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313 | (if full-directory-p |
314 | (concat (file-name-as-directory file) ".") | |
315 | file)) | |
316 | @end group | |
317 | @end smallexample | |
318 | @end defun | |
319 | ||
bb5d6d34 KG |
320 | @defun process-file program &optional infile buffer display &rest args |
321 | This function processes files synchronously in a separate process. It | |
322 | is similar to @code{call-process} but may invoke a file handler based | |
323 | on the value of the variable @code{default-directory}. The current | |
324 | working directory of the subprocess is @code{default-directory}. | |
325 | ||
326 | The arguments are handled in almost the same way as for | |
327 | @code{call-process}, with the following differences: | |
328 | ||
329 | Some file handlers may not support all combinations and forms of the | |
330 | arguments @var{infile}, @var{buffer}, and @var{display}. For example, | |
f8684c07 | 331 | some file handlers might behave as if @var{display} were @code{nil}, |
bb5d6d34 KG |
332 | regardless of the value actually passed. As another example, some |
333 | file handlers might not support separating standard output and error | |
334 | output by way of the @var{buffer} argument. | |
335 | ||
336 | If a file handler is invoked, it determines the program to run based | |
337 | on the first argument @var{program}. For instance, consider that a | |
338 | handler for remote files is invoked. Then the path that is used for | |
339 | searching the program might be different than @code{exec-path}. | |
340 | ||
341 | The second argument @var{infile} may invoke a file handler. The file | |
342 | handler could be different from the handler chosen for the | |
343 | @code{process-file} function itself. (For example, | |
344 | @code{default-directory} could be on a remote host, whereas | |
345 | @var{infile} is on another remote host. Or @code{default-directory} | |
346 | could be non-special, whereas @var{infile} is on a remote host.) | |
347 | ||
348 | If @var{buffer} has the form @code{(@var{real-destination} | |
349 | @var{error-destination})}, and @var{error-destination} names a file, | |
350 | then the same remarks as for @var{infile} apply. | |
351 | ||
352 | The remaining arguments (@var{args}) will be passed to the process | |
353 | verbatim. Emacs is not involved in processing file names that are | |
354 | present in @var{args}. To avoid confusion, it may be best to avoid | |
355 | absolute file names in @var{args}, but rather to specify all file | |
356 | names as relative to @code{default-directory}. The function | |
357 | @code{file-relative-name} is useful for constructing such relative | |
358 | file names. | |
359 | @end defun | |
360 | ||
22697dac | 361 | @defun call-process-region start end program &optional delete destination display &rest args |
8241495d | 362 | This function sends the text from @var{start} to @var{end} as |
73804d4b | 363 | standard input to a process running @var{program}. It deletes the text |
f9f59935 RS |
364 | sent if @var{delete} is non-@code{nil}; this is useful when |
365 | @var{destination} is @code{t}, to insert the output in the current | |
366 | buffer in place of the input. | |
73804d4b | 367 | |
22697dac | 368 | The arguments @var{destination} and @var{display} control what to do |
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369 | with the output from the subprocess, and whether to update the display |
370 | as it comes in. For details, see the description of | |
22697dac | 371 | @code{call-process}, above. If @var{destination} is the integer 0, |
73804d4b | 372 | @code{call-process-region} discards the output and returns @code{nil} |
8241495d | 373 | immediately, without waiting for the subprocess to finish (this only |
4f939ab8 | 374 | works if asynchronous subprocesses are supported). |
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375 | |
376 | The remaining arguments, @var{args}, are strings that specify command | |
377 | line arguments for the program. | |
378 | ||
379 | The return value of @code{call-process-region} is just like that of | |
380 | @code{call-process}: @code{nil} if you told it to return without | |
381 | waiting; otherwise, a number or string which indicates how the | |
382 | subprocess terminated. | |
383 | ||
384 | In the following example, we use @code{call-process-region} to run the | |
385 | @code{cat} utility, with standard input being the first five characters | |
386 | in buffer @samp{foo} (the word @samp{input}). @code{cat} copies its | |
387 | standard input into its standard output. Since the argument | |
22697dac | 388 | @var{destination} is @code{t}, this output is inserted in the current |
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389 | buffer. |
390 | ||
391 | @smallexample | |
392 | @group | |
393 | ---------- Buffer: foo ---------- | |
394 | input@point{} | |
395 | ---------- Buffer: foo ---------- | |
396 | @end group | |
397 | ||
398 | @group | |
399 | (call-process-region 1 6 "cat" nil t) | |
8241495d | 400 | @result{} 0 |
73804d4b RS |
401 | |
402 | ---------- Buffer: foo ---------- | |
403 | inputinput@point{} | |
404 | ---------- Buffer: foo ---------- | |
405 | @end group | |
406 | @end smallexample | |
407 | ||
408 | The @code{shell-command-on-region} command uses | |
409 | @code{call-process-region} like this: | |
410 | ||
411 | @smallexample | |
412 | @group | |
177c0ea7 JB |
413 | (call-process-region |
414 | start end | |
73804d4b RS |
415 | shell-file-name ; @r{Name of program.} |
416 | nil ; @r{Do not delete region.} | |
417 | buffer ; @r{Send output to @code{buffer}.} | |
418 | nil ; @r{No redisplay during output.} | |
419 | "-c" command) ; @r{Arguments for the shell.} | |
420 | @end group | |
421 | @end smallexample | |
422 | @end defun | |
423 | ||
4bb24054 RS |
424 | @defun call-process-shell-command command &optional infile destination display &rest args |
425 | This function executes the shell command @var{command} synchronously | |
38e82e48 | 426 | in a separate process. The final arguments @var{args} are additional |
4bb24054 RS |
427 | arguments to add at the end of @var{command}. The other arguments |
428 | are handled as in @code{call-process}. | |
429 | @end defun | |
430 | ||
f9f59935 RS |
431 | @defun shell-command-to-string command |
432 | This function executes @var{command} (a string) as a shell command, | |
433 | then returns the command's output as a string. | |
434 | @end defun | |
435 | ||
73804d4b RS |
436 | @node Asynchronous Processes |
437 | @section Creating an Asynchronous Process | |
438 | @cindex asynchronous subprocess | |
439 | ||
1911e6e5 RS |
440 | After an @dfn{asynchronous process} is created, Emacs and the subprocess |
441 | both continue running immediately. The process thereafter runs | |
a9f0a989 | 442 | in parallel with Emacs, and the two can communicate with each other |
8241495d | 443 | using the functions described in the following sections. However, |
a9f0a989 RS |
444 | communication is only partially asynchronous: Emacs sends data to the |
445 | process only when certain functions are called, and Emacs accepts data | |
446 | from the process only when Emacs is waiting for input or for a time | |
447 | delay. | |
448 | ||
449 | Here we describe how to create an asynchronous process. | |
73804d4b RS |
450 | |
451 | @defun start-process name buffer-or-name program &rest args | |
452 | This function creates a new asynchronous subprocess and starts the | |
453 | program @var{program} running in it. It returns a process object that | |
454 | stands for the new subprocess in Lisp. The argument @var{name} | |
455 | specifies the name for the process object; if a process with this name | |
f9f59935 RS |
456 | already exists, then @var{name} is modified (by appending @samp{<1>}, |
457 | etc.) to be unique. The buffer @var{buffer-or-name} is the buffer to | |
73804d4b RS |
458 | associate with the process. |
459 | ||
460 | The remaining arguments, @var{args}, are strings that specify command | |
461 | line arguments for the program. | |
462 | ||
463 | In the example below, the first process is started and runs (rather, | |
464 | sleeps) for 100 seconds. Meanwhile, the second process is started, and | |
465 | given the name @samp{my-process<1>} for the sake of uniqueness. It | |
466 | inserts the directory listing at the end of the buffer @samp{foo}, | |
467 | before the first process finishes. Then it finishes, and a message to | |
468 | that effect is inserted in the buffer. Much later, the first process | |
469 | finishes, and another message is inserted in the buffer for it. | |
470 | ||
471 | @smallexample | |
472 | @group | |
473 | (start-process "my-process" "foo" "sleep" "100") | |
474 | @result{} #<process my-process> | |
475 | @end group | |
476 | ||
477 | @group | |
478 | (start-process "my-process" "foo" "ls" "-l" "/user/lewis/bin") | |
479 | @result{} #<process my-process<1>> | |
480 | ||
481 | ---------- Buffer: foo ---------- | |
482 | total 2 | |
483 | lrwxrwxrwx 1 lewis 14 Jul 22 10:12 gnuemacs --> /emacs | |
484 | -rwxrwxrwx 1 lewis 19 Jul 30 21:02 lemon | |
485 | ||
486 | Process my-process<1> finished | |
487 | ||
488 | Process my-process finished | |
489 | ---------- Buffer: foo ---------- | |
490 | @end group | |
491 | @end smallexample | |
492 | @end defun | |
493 | ||
494 | @defun start-process-shell-command name buffer-or-name command &rest command-args | |
495 | This function is like @code{start-process} except that it uses a shell | |
496 | to execute the specified command. The argument @var{command} is a shell | |
497 | command name, and @var{command-args} are the arguments for the shell | |
f9f59935 RS |
498 | command. The variable @code{shell-file-name} specifies which shell to |
499 | use. | |
969fe9b5 RS |
500 | |
501 | The point of running a program through the shell, rather than directly | |
502 | with @code{start-process}, is so that you can employ shell features such | |
503 | as wildcards in the arguments. It follows that if you include an | |
8241495d | 504 | arbitrary user-specified arguments in the command, you should quote it |
969fe9b5 | 505 | with @code{shell-quote-argument} first, so that any special shell |
8241495d RS |
506 | characters do @emph{not} have their special shell meanings. @xref{Shell |
507 | Arguments}. | |
73804d4b RS |
508 | @end defun |
509 | ||
510 | @defvar process-connection-type | |
511 | @cindex pipes | |
ad800164 | 512 | @cindex @acronym{PTY}s |
73804d4b | 513 | This variable controls the type of device used to communicate with |
ad800164 | 514 | asynchronous subprocesses. If it is non-@code{nil}, then @acronym{PTY}s are |
bfe721d1 | 515 | used, when available. Otherwise, pipes are used. |
73804d4b | 516 | |
ad800164 | 517 | @acronym{PTY}s are usually preferable for processes visible to the user, as |
73804d4b | 518 | in Shell mode, because they allow job control (@kbd{C-c}, @kbd{C-z}, |
f9f59935 RS |
519 | etc.) to work between the process and its children, whereas pipes do |
520 | not. For subprocesses used for internal purposes by programs, it is | |
521 | often better to use a pipe, because they are more efficient. In | |
ad800164 | 522 | addition, the total number of @acronym{PTY}s is limited on many systems and |
f9f59935 | 523 | it is good not to waste them. |
73804d4b | 524 | |
edc590bb | 525 | The value of @code{process-connection-type} takes effect when |
73804d4b RS |
526 | @code{start-process} is called. So you can specify how to communicate |
527 | with one subprocess by binding the variable around the call to | |
528 | @code{start-process}. | |
529 | ||
530 | @smallexample | |
531 | @group | |
532 | (let ((process-connection-type nil)) ; @r{Use a pipe.} | |
533 | (start-process @dots{})) | |
534 | @end group | |
535 | @end smallexample | |
22697dac KH |
536 | |
537 | To determine whether a given subprocess actually got a pipe or a | |
ad800164 | 538 | @acronym{PTY}, use the function @code{process-tty-name} (@pxref{Process |
22697dac | 539 | Information}). |
73804d4b RS |
540 | @end defvar |
541 | ||
542 | @node Deleting Processes | |
543 | @section Deleting Processes | |
544 | @cindex deleting processes | |
545 | ||
546 | @dfn{Deleting a process} disconnects Emacs immediately from the | |
5517ea8a RS |
547 | subprocess. Processes are deleted automatically after they terminate, |
548 | but not necessarily right away. You can delete a process explicitly | |
549 | at any time. If you delete a terminated process explicitly before it | |
fea5a6d5 | 550 | is deleted automatically, no harm results. Deleting a running |
edc590bb | 551 | process sends a signal to terminate it (and its child processes if |
fea5a6d5 | 552 | any), and calls the process sentinel if it has one. @xref{Sentinels}. |
5517ea8a | 553 | |
fea5a6d5 RS |
554 | When a process is deleted, the process object itself continues to |
555 | exist as long as other Lisp objects point to it. All the Lisp | |
556 | primitives that work on process objects accept deleted processes, but | |
557 | those that do I/O or send signals will report an error. The process | |
558 | mark continues to point to the same place as before, usually into a | |
559 | buffer where output from the process was being inserted. | |
73804d4b | 560 | |
1911e6e5 | 561 | @defopt delete-exited-processes |
73804d4b RS |
562 | This variable controls automatic deletion of processes that have |
563 | terminated (due to calling @code{exit} or to a signal). If it is | |
564 | @code{nil}, then they continue to exist until the user runs | |
565 | @code{list-processes}. Otherwise, they are deleted immediately after | |
566 | they exit. | |
1911e6e5 | 567 | @end defopt |
73804d4b | 568 | |
fea5a6d5 RS |
569 | @defun delete-process process |
570 | This function deletes a process, killing it with a @code{SIGKILL} | |
571 | signal. The argument may be a process, the name of a process, a | |
572 | buffer, or the name of a buffer. (A buffer or buffer-name stands for | |
573 | the process that @code{get-buffer-process} returns.) Calling | |
574 | @code{delete-process} on a running process terminates it, updates the | |
575 | process status, and runs the sentinel (if any) immediately. If the | |
576 | process has already terminated, calling @code{delete-process} has no | |
577 | effect on its status, or on the running of its sentinel (which will | |
578 | happen sooner or later). | |
73804d4b RS |
579 | |
580 | @smallexample | |
581 | @group | |
582 | (delete-process "*shell*") | |
583 | @result{} nil | |
584 | @end group | |
585 | @end smallexample | |
586 | @end defun | |
587 | ||
73804d4b RS |
588 | @node Process Information |
589 | @section Process Information | |
590 | ||
591 | Several functions return information about processes. | |
592 | @code{list-processes} is provided for interactive use. | |
593 | ||
4bb24054 | 594 | @deffn Command list-processes &optional query-only |
73804d4b RS |
595 | This command displays a listing of all living processes. In addition, |
596 | it finally deletes any process whose status was @samp{Exited} or | |
597 | @samp{Signaled}. It returns @code{nil}. | |
4bb24054 RS |
598 | |
599 | If @var{query-only} is non-@code{nil} then it lists only processes | |
600 | whose query flag is non-@code{nil}. @xref{Query Before Exit}. | |
73804d4b RS |
601 | @end deffn |
602 | ||
603 | @defun process-list | |
604 | This function returns a list of all processes that have not been deleted. | |
605 | ||
606 | @smallexample | |
607 | @group | |
608 | (process-list) | |
609 | @result{} (#<process display-time> #<process shell>) | |
610 | @end group | |
611 | @end smallexample | |
612 | @end defun | |
613 | ||
614 | @defun get-process name | |
615 | This function returns the process named @var{name}, or @code{nil} if | |
616 | there is none. An error is signaled if @var{name} is not a string. | |
617 | ||
618 | @smallexample | |
619 | @group | |
620 | (get-process "shell") | |
621 | @result{} #<process shell> | |
622 | @end group | |
623 | @end smallexample | |
624 | @end defun | |
625 | ||
626 | @defun process-command process | |
627 | This function returns the command that was executed to start | |
628 | @var{process}. This is a list of strings, the first string being the | |
629 | program executed and the rest of the strings being the arguments that | |
630 | were given to the program. | |
631 | ||
632 | @smallexample | |
633 | @group | |
634 | (process-command (get-process "shell")) | |
635 | @result{} ("/bin/csh" "-i") | |
636 | @end group | |
637 | @end smallexample | |
638 | @end defun | |
639 | ||
640 | @defun process-id process | |
ad800164 | 641 | This function returns the @acronym{PID} of @var{process}. This is an |
78608595 | 642 | integer that distinguishes the process @var{process} from all other |
73804d4b | 643 | processes running on the same computer at the current time. The |
ad800164 | 644 | @acronym{PID} of a process is chosen by the operating system kernel when the |
73804d4b RS |
645 | process is started and remains constant as long as the process exists. |
646 | @end defun | |
647 | ||
648 | @defun process-name process | |
649 | This function returns the name of @var{process}. | |
650 | @end defun | |
651 | ||
652 | @defun process-status process-name | |
653 | This function returns the status of @var{process-name} as a symbol. | |
654 | The argument @var{process-name} must be a process, a buffer, a | |
655 | process name (string) or a buffer name (string). | |
656 | ||
657 | The possible values for an actual subprocess are: | |
658 | ||
659 | @table @code | |
660 | @item run | |
661 | for a process that is running. | |
662 | @item stop | |
663 | for a process that is stopped but continuable. | |
664 | @item exit | |
665 | for a process that has exited. | |
666 | @item signal | |
667 | for a process that has received a fatal signal. | |
668 | @item open | |
669 | for a network connection that is open. | |
670 | @item closed | |
671 | for a network connection that is closed. Once a connection | |
672 | is closed, you cannot reopen it, though you might be able to open | |
673 | a new connection to the same place. | |
4bb24054 RS |
674 | @item connect |
675 | for a non-blocking connection that is waiting to complete. | |
676 | @item failed | |
677 | for a non-blocking connection that has failed to complete. | |
678 | @item listen | |
679 | for a network server that is listening. | |
73804d4b RS |
680 | @item nil |
681 | if @var{process-name} is not the name of an existing process. | |
682 | @end table | |
683 | ||
684 | @smallexample | |
685 | @group | |
686 | (process-status "shell") | |
687 | @result{} run | |
688 | @end group | |
689 | @group | |
690 | (process-status (get-buffer "*shell*")) | |
691 | @result{} run | |
692 | @end group | |
693 | @group | |
694 | x | |
695 | @result{} #<process xx<1>> | |
696 | (process-status x) | |
697 | @result{} exit | |
698 | @end group | |
699 | @end smallexample | |
700 | ||
701 | For a network connection, @code{process-status} returns one of the symbols | |
702 | @code{open} or @code{closed}. The latter means that the other side | |
703 | closed the connection, or Emacs did @code{delete-process}. | |
73804d4b RS |
704 | @end defun |
705 | ||
706 | @defun process-exit-status process | |
707 | This function returns the exit status of @var{process} or the signal | |
708 | number that killed it. (Use the result of @code{process-status} to | |
709 | determine which of those it is.) If @var{process} has not yet | |
710 | terminated, the value is 0. | |
711 | @end defun | |
712 | ||
22697dac KH |
713 | @defun process-tty-name process |
714 | This function returns the terminal name that @var{process} is using for | |
715 | its communication with Emacs---or @code{nil} if it is using pipes | |
716 | instead of a terminal (see @code{process-connection-type} in | |
717 | @ref{Asynchronous Processes}). | |
718 | @end defun | |
719 | ||
f9f59935 | 720 | @defun process-coding-system process |
7baeca0c | 721 | @anchor{Coding systems for a subprocess} |
f9f59935 RS |
722 | This function returns a cons cell describing the coding systems in use |
723 | for decoding output from @var{process} and for encoding input to | |
724 | @var{process} (@pxref{Coding Systems}). The value has this form: | |
725 | ||
726 | @example | |
969fe9b5 | 727 | (@var{coding-system-for-decoding} . @var{coding-system-for-encoding}) |
f9f59935 RS |
728 | @end example |
729 | @end defun | |
730 | ||
fea5a6d5 | 731 | @defun set-process-coding-system process &optional decoding-system encoding-system |
f9f59935 RS |
732 | This function specifies the coding systems to use for subsequent output |
733 | from and input to @var{process}. It will use @var{decoding-system} to | |
734 | decode subprocess output, and @var{encoding-system} to encode subprocess | |
735 | input. | |
4bb24054 RS |
736 | @end defun |
737 | ||
738 | Every process also has a property list that you can use to store | |
739 | miscellaneous values associated with the process. | |
740 | ||
741 | @defun process-get process propname | |
742 | This function returns the value of the @var{propname} property | |
743 | of @var{process}. | |
744 | @end defun | |
745 | ||
746 | @defun process-put process propname value | |
747 | This function sets the value of the @var{propname} property | |
748 | of @var{process} to @var{value}. | |
749 | @end defun | |
750 | ||
751 | @defun process-plist process | |
752 | This function returns the process plist of @var{process}. | |
753 | @end defun | |
754 | ||
755 | @defun set-process-plist process plist | |
756 | This function sets the process plist of @var{process} to @var{plist}. | |
f9f59935 RS |
757 | @end defun |
758 | ||
73804d4b RS |
759 | @node Input to Processes |
760 | @section Sending Input to Processes | |
761 | @cindex process input | |
762 | ||
763 | Asynchronous subprocesses receive input when it is sent to them by | |
764 | Emacs, which is done with the functions in this section. You must | |
765 | specify the process to send input to, and the input data to send. The | |
766 | data appears on the ``standard input'' of the subprocess. | |
767 | ||
768 | Some operating systems have limited space for buffered input in a | |
ad800164 | 769 | @acronym{PTY}. On these systems, Emacs sends an @acronym{EOF} periodically amidst |
73804d4b | 770 | the other characters, to force them through. For most programs, |
ad800164 | 771 | these @acronym{EOF}s do no harm. |
73804d4b | 772 | |
f9f59935 | 773 | Subprocess input is normally encoded using a coding system before the |
a9f0a989 RS |
774 | subprocess receives it, much like text written into a file. You can use |
775 | @code{set-process-coding-system} to specify which coding system to use | |
776 | (@pxref{Process Information}). Otherwise, the coding system comes from | |
777 | @code{coding-system-for-write}, if that is non-@code{nil}; or else from | |
778 | the defaulting mechanism (@pxref{Default Coding Systems}). | |
f9f59935 | 779 | |
b6954afd RS |
780 | Sometimes the system is unable to accept input for that process, |
781 | because the input buffer is full. When this happens, the send functions | |
782 | wait a short while, accepting output from subprocesses, and then try | |
783 | again. This gives the subprocess a chance to read more of its pending | |
784 | input and make space in the buffer. It also allows filters, sentinels | |
785 | and timers to run---so take account of that in writing your code. | |
786 | ||
fea5a6d5 RS |
787 | In these functions, the @var{process} argument can be a process or |
788 | the name of a process, or a buffer or buffer name (which stands | |
789 | for a process via @code{get-buffer-process}). @code{nil} means | |
790 | the current buffer's process. | |
791 | ||
792 | @defun process-send-string process string | |
793 | This function sends @var{process} the contents of @var{string} as | |
794 | standard input. If it is @code{nil}, the current buffer's process is used. | |
73804d4b RS |
795 | |
796 | The function returns @code{nil}. | |
797 | ||
798 | @smallexample | |
799 | @group | |
800 | (process-send-string "shell<1>" "ls\n") | |
801 | @result{} nil | |
802 | @end group | |
803 | ||
804 | ||
805 | @group | |
806 | ---------- Buffer: *shell* ---------- | |
807 | ... | |
808 | introduction.texi syntax-tables.texi~ | |
809 | introduction.texi~ text.texi | |
810 | introduction.txt text.texi~ | |
811 | ... | |
812 | ---------- Buffer: *shell* ---------- | |
813 | @end group | |
814 | @end smallexample | |
815 | @end defun | |
816 | ||
fea5a6d5 | 817 | @defun process-send-region process start end |
73804d4b | 818 | This function sends the text in the region defined by @var{start} and |
fea5a6d5 | 819 | @var{end} as standard input to @var{process}. |
73804d4b RS |
820 | |
821 | An error is signaled unless both @var{start} and @var{end} are | |
822 | integers or markers that indicate positions in the current buffer. (It | |
823 | is unimportant which number is larger.) | |
8241495d | 824 | @end defun |
73804d4b | 825 | |
fea5a6d5 RS |
826 | @defun process-send-eof &optional process |
827 | This function makes @var{process} see an end-of-file in its | |
ad800164 | 828 | input. The @acronym{EOF} comes after any text already sent to it. |
73804d4b | 829 | |
fea5a6d5 | 830 | The function returns @var{process}. |
73804d4b RS |
831 | |
832 | @smallexample | |
833 | @group | |
834 | (process-send-eof "shell") | |
835 | @result{} "shell" | |
836 | @end group | |
837 | @end smallexample | |
838 | @end defun | |
839 | ||
b6954afd RS |
840 | @defun process-running-child-p process |
841 | @tindex process-running-child-p process | |
842 | This function will tell you whether a subprocess has given control of | |
843 | its terminal to its own child process. The value is @code{t} if this is | |
844 | true, or if Emacs cannot tell; it is @code{nil} if Emacs can be certain | |
845 | that this is not so. | |
846 | @end defun | |
847 | ||
73804d4b RS |
848 | @node Signals to Processes |
849 | @section Sending Signals to Processes | |
850 | @cindex process signals | |
851 | @cindex sending signals | |
852 | @cindex signals | |
853 | ||
854 | @dfn{Sending a signal} to a subprocess is a way of interrupting its | |
855 | activities. There are several different signals, each with its own | |
856 | meaning. The set of signals and their names is defined by the operating | |
857 | system. For example, the signal @code{SIGINT} means that the user has | |
858 | typed @kbd{C-c}, or that some analogous thing has happened. | |
859 | ||
860 | Each signal has a standard effect on the subprocess. Most signals | |
861 | kill the subprocess, but some stop or resume execution instead. Most | |
862 | signals can optionally be handled by programs; if the program handles | |
863 | the signal, then we can say nothing in general about its effects. | |
864 | ||
865 | You can send signals explicitly by calling the functions in this | |
866 | section. Emacs also sends signals automatically at certain times: | |
867 | killing a buffer sends a @code{SIGHUP} signal to all its associated | |
868 | processes; killing Emacs sends a @code{SIGHUP} signal to all remaining | |
869 | processes. (@code{SIGHUP} is a signal that usually indicates that the | |
870 | user hung up the phone.) | |
871 | ||
872 | Each of the signal-sending functions takes two optional arguments: | |
873 | @var{process-name} and @var{current-group}. | |
874 | ||
fea5a6d5 RS |
875 | The argument @var{process} must be either a process, a process |
876 | name, a buffer, a buffer name, or @code{nil}. A buffer or buffer name | |
877 | stands for a process through @code{get-buffer-process}. @code{nil} | |
878 | stands for the process associated with the current buffer. An error | |
879 | is signaled if @var{process} does not identify a process. | |
73804d4b RS |
880 | |
881 | The argument @var{current-group} is a flag that makes a difference | |
882 | when you are running a job-control shell as an Emacs subprocess. If it | |
883 | is non-@code{nil}, then the signal is sent to the current process-group | |
78608595 | 884 | of the terminal that Emacs uses to communicate with the subprocess. If |
73804d4b RS |
885 | the process is a job-control shell, this means the shell's current |
886 | subjob. If it is @code{nil}, the signal is sent to the process group of | |
887 | the immediate subprocess of Emacs. If the subprocess is a job-control | |
888 | shell, this is the shell itself. | |
889 | ||
890 | The flag @var{current-group} has no effect when a pipe is used to | |
891 | communicate with the subprocess, because the operating system does not | |
892 | support the distinction in the case of pipes. For the same reason, | |
893 | job-control shells won't work when a pipe is used. See | |
894 | @code{process-connection-type} in @ref{Asynchronous Processes}. | |
895 | ||
fea5a6d5 RS |
896 | @defun interrupt-process &optional process current-group |
897 | This function interrupts the process @var{process} by sending the | |
73804d4b RS |
898 | signal @code{SIGINT}. Outside of Emacs, typing the ``interrupt |
899 | character'' (normally @kbd{C-c} on some systems, and @code{DEL} on | |
900 | others) sends this signal. When the argument @var{current-group} is | |
901 | non-@code{nil}, you can think of this function as ``typing @kbd{C-c}'' | |
902 | on the terminal by which Emacs talks to the subprocess. | |
903 | @end defun | |
904 | ||
fea5a6d5 RS |
905 | @defun kill-process &optional process current-group |
906 | This function kills the process @var{process} by sending the | |
73804d4b RS |
907 | signal @code{SIGKILL}. This signal kills the subprocess immediately, |
908 | and cannot be handled by the subprocess. | |
909 | @end defun | |
910 | ||
fea5a6d5 | 911 | @defun quit-process &optional process current-group |
73804d4b | 912 | This function sends the signal @code{SIGQUIT} to the process |
fea5a6d5 | 913 | @var{process}. This signal is the one sent by the ``quit |
73804d4b RS |
914 | character'' (usually @kbd{C-b} or @kbd{C-\}) when you are not inside |
915 | Emacs. | |
916 | @end defun | |
917 | ||
fea5a6d5 RS |
918 | @defun stop-process &optional process current-group |
919 | This function stops the process @var{process} by sending the | |
73804d4b RS |
920 | signal @code{SIGTSTP}. Use @code{continue-process} to resume its |
921 | execution. | |
922 | ||
969fe9b5 | 923 | Outside of Emacs, on systems with job control, the ``stop character'' |
f9f59935 RS |
924 | (usually @kbd{C-z}) normally sends this signal. When |
925 | @var{current-group} is non-@code{nil}, you can think of this function as | |
926 | ``typing @kbd{C-z}'' on the terminal Emacs uses to communicate with the | |
927 | subprocess. | |
73804d4b RS |
928 | @end defun |
929 | ||
fea5a6d5 | 930 | @defun continue-process &optional process current-group |
73804d4b | 931 | This function resumes execution of the process @var{process} by sending |
fea5a6d5 | 932 | it the signal @code{SIGCONT}. This presumes that @var{process} was |
73804d4b RS |
933 | stopped previously. |
934 | @end defun | |
935 | ||
936 | @c Emacs 19 feature | |
4bb24054 RS |
937 | @defun signal-process process signal |
938 | This function sends a signal to process @var{process}. The argument | |
939 | @var{signal} specifies which signal to send; it should be an integer. | |
940 | ||
fea5a6d5 RS |
941 | The @var{process} argument can be a system process @acronym{ID}; that |
942 | allows you to send signals to processes that are not children of | |
943 | Emacs. | |
73804d4b RS |
944 | @end defun |
945 | ||
946 | @node Output from Processes | |
947 | @section Receiving Output from Processes | |
948 | @cindex process output | |
949 | @cindex output from processes | |
950 | ||
951 | There are two ways to receive the output that a subprocess writes to | |
952 | its standard output stream. The output can be inserted in a buffer, | |
953 | which is called the associated buffer of the process, or a function | |
78608595 RS |
954 | called the @dfn{filter function} can be called to act on the output. If |
955 | the process has no buffer and no filter function, its output is | |
956 | discarded. | |
177c0ea7 | 957 | |
edc590bb RS |
958 | When a subprocess terminates, Emacs reads any pending output, |
959 | then stops reading output from that subprocess. Therefore, if the | |
960 | subprocess has children that are still live and still producing | |
961 | output, Emacs won't receive that output. | |
962 | ||
a9f0a989 RS |
963 | Output from a subprocess can arrive only while Emacs is waiting: when |
964 | reading terminal input, in @code{sit-for} and @code{sleep-for} | |
965 | (@pxref{Waiting}), and in @code{accept-process-output} (@pxref{Accepting | |
966 | Output}). This minimizes the problem of timing errors that usually | |
967 | plague parallel programming. For example, you can safely create a | |
968 | process and only then specify its buffer or filter function; no output | |
969 | can arrive before you finish, if the code in between does not call any | |
970 | primitive that waits. | |
971 | ||
bfa96fa2 KS |
972 | @defvar process-adaptive-read-buffering |
973 | On some systems, when Emacs reads the output from a subprocess, the | |
974 | output data is read in very small blocks, potentially resulting in | |
975 | very poor performance. This behaviour can be remedied to some extent | |
976 | by setting the variable @var{process-adaptive-read-buffering} to a | |
c1aa4864 | 977 | non-@code{nil} value (the default), as it will automatically delay reading |
bfa96fa2 KS |
978 | from such processes, thus allowing them to produce more output before |
979 | Emacs tries to read it. | |
980 | @end defvar | |
981 | ||
8f3efb4e RS |
982 | It is impossible to separate the standard output and standard error |
983 | streams of the subprocess, because Emacs normally spawns the subprocess | |
984 | inside a pseudo-TTY, and a pseudo-TTY has only one output channel. If | |
985 | you want to keep the output to those streams separate, you should | |
4810d170 | 986 | redirect one of them to a file---for example, by using an appropriate |
8f3efb4e RS |
987 | shell command. |
988 | ||
73804d4b | 989 | @menu |
582ef186 RS |
990 | * Process Buffers:: If no filter, output is put in a buffer. |
991 | * Filter Functions:: Filter functions accept output from the process. | |
591a3500 | 992 | * Decoding Output:: Filters can get unibyte or multibyte strings. |
582ef186 | 993 | * Accepting Output:: How to wait until process output arrives. |
73804d4b RS |
994 | @end menu |
995 | ||
996 | @node Process Buffers | |
997 | @subsection Process Buffers | |
998 | ||
999 | A process can (and usually does) have an @dfn{associated buffer}, | |
1000 | which is an ordinary Emacs buffer that is used for two purposes: storing | |
1001 | the output from the process, and deciding when to kill the process. You | |
1002 | can also use the buffer to identify a process to operate on, since in | |
1003 | normal practice only one process is associated with any given buffer. | |
1004 | Many applications of processes also use the buffer for editing input to | |
1005 | be sent to the process, but this is not built into Emacs Lisp. | |
1006 | ||
1007 | Unless the process has a filter function (@pxref{Filter Functions}), | |
1008 | its output is inserted in the associated buffer. The position to insert | |
78608595 RS |
1009 | the output is determined by the @code{process-mark}, which is then |
1010 | updated to point to the end of the text just inserted. Usually, but not | |
1011 | always, the @code{process-mark} is at the end of the buffer. | |
73804d4b RS |
1012 | |
1013 | @defun process-buffer process | |
1014 | This function returns the associated buffer of the process | |
1015 | @var{process}. | |
1016 | ||
1017 | @smallexample | |
1018 | @group | |
1019 | (process-buffer (get-process "shell")) | |
1020 | @result{} #<buffer *shell*> | |
1021 | @end group | |
1022 | @end smallexample | |
1023 | @end defun | |
1024 | ||
1025 | @defun process-mark process | |
1026 | This function returns the process marker for @var{process}, which is the | |
1027 | marker that says where to insert output from the process. | |
1028 | ||
1029 | If @var{process} does not have a buffer, @code{process-mark} returns a | |
1030 | marker that points nowhere. | |
1031 | ||
1032 | Insertion of process output in a buffer uses this marker to decide where | |
1033 | to insert, and updates it to point after the inserted text. That is why | |
1034 | successive batches of output are inserted consecutively. | |
1035 | ||
1036 | Filter functions normally should use this marker in the same fashion | |
1037 | as is done by direct insertion of output in the buffer. A good | |
1038 | example of a filter function that uses @code{process-mark} is found at | |
1039 | the end of the following section. | |
1040 | ||
1041 | When the user is expected to enter input in the process buffer for | |
f9f59935 RS |
1042 | transmission to the process, the process marker separates the new input |
1043 | from previous output. | |
73804d4b RS |
1044 | @end defun |
1045 | ||
1046 | @defun set-process-buffer process buffer | |
1047 | This function sets the buffer associated with @var{process} to | |
1048 | @var{buffer}. If @var{buffer} is @code{nil}, the process becomes | |
1049 | associated with no buffer. | |
1050 | @end defun | |
1051 | ||
1052 | @defun get-buffer-process buffer-or-name | |
5517ea8a RS |
1053 | This function returns a nondeleted process associated with the buffer |
1054 | specified by @var{buffer-or-name}. If there are several processes | |
1055 | associated with it, this function chooses one (currently, the one most | |
1056 | recently created, but don't count on that). Deletion of a process | |
1057 | (see @code{delete-process}) makes it ineligible for this function to | |
1058 | return. | |
1059 | ||
1060 | It is usually a bad idea to have more than one process associated with | |
1061 | the same buffer. | |
73804d4b RS |
1062 | |
1063 | @smallexample | |
1064 | @group | |
1065 | (get-buffer-process "*shell*") | |
1066 | @result{} #<process shell> | |
1067 | @end group | |
1068 | @end smallexample | |
1069 | ||
1070 | Killing the process's buffer deletes the process, which kills the | |
1071 | subprocess with a @code{SIGHUP} signal (@pxref{Signals to Processes}). | |
1072 | @end defun | |
1073 | ||
1074 | @node Filter Functions | |
1075 | @subsection Process Filter Functions | |
1076 | @cindex filter function | |
1077 | @cindex process filter | |
1078 | ||
1079 | A process @dfn{filter function} is a function that receives the | |
1080 | standard output from the associated process. If a process has a filter, | |
78608595 RS |
1081 | then @emph{all} output from that process is passed to the filter. The |
1082 | process buffer is used directly for output from the process only when | |
1083 | there is no filter. | |
73804d4b | 1084 | |
a9f0a989 RS |
1085 | The filter function can only be called when Emacs is waiting for |
1086 | something, because process output arrives only at such times. Emacs | |
1087 | waits when reading terminal input, in @code{sit-for} and | |
1088 | @code{sleep-for} (@pxref{Waiting}), and in @code{accept-process-output} | |
1089 | (@pxref{Accepting Output}). | |
1090 | ||
f9f59935 RS |
1091 | A filter function must accept two arguments: the associated process |
1092 | and a string, which is output just received from it. The function is | |
1093 | then free to do whatever it chooses with the output. | |
73804d4b | 1094 | |
73804d4b RS |
1095 | Quitting is normally inhibited within a filter function---otherwise, |
1096 | the effect of typing @kbd{C-g} at command level or to quit a user | |
1097 | command would be unpredictable. If you want to permit quitting inside a | |
1098 | filter function, bind @code{inhibit-quit} to @code{nil}. | |
1099 | @xref{Quitting}. | |
1100 | ||
22697dac KH |
1101 | If an error happens during execution of a filter function, it is |
1102 | caught automatically, so that it doesn't stop the execution of whatever | |
eaac2be1 | 1103 | program was running when the filter function was started. However, if |
22697dac KH |
1104 | @code{debug-on-error} is non-@code{nil}, the error-catching is turned |
1105 | off. This makes it possible to use the Lisp debugger to debug the | |
1106 | filter function. @xref{Debugger}. | |
1107 | ||
73804d4b RS |
1108 | Many filter functions sometimes or always insert the text in the |
1109 | process's buffer, mimicking the actions of Emacs when there is no | |
1110 | filter. Such filter functions need to use @code{set-buffer} in order to | |
1111 | be sure to insert in that buffer. To avoid setting the current buffer | |
f9f59935 RS |
1112 | semipermanently, these filter functions must save and restore the |
1113 | current buffer. They should also update the process marker, and in some | |
1114 | cases update the value of point. Here is how to do these things: | |
73804d4b RS |
1115 | |
1116 | @smallexample | |
1117 | @group | |
1118 | (defun ordinary-insertion-filter (proc string) | |
f9f59935 RS |
1119 | (with-current-buffer (process-buffer proc) |
1120 | (let ((moving (= (point) (process-mark proc)))) | |
73804d4b RS |
1121 | @end group |
1122 | @group | |
f9f59935 RS |
1123 | (save-excursion |
1124 | ;; @r{Insert the text, advancing the process marker.} | |
1125 | (goto-char (process-mark proc)) | |
1126 | (insert string) | |
1127 | (set-marker (process-mark proc) (point))) | |
1128 | (if moving (goto-char (process-mark proc)))))) | |
73804d4b RS |
1129 | @end group |
1130 | @end smallexample | |
1131 | ||
1132 | @noindent | |
f9f59935 RS |
1133 | The reason to use @code{with-current-buffer}, rather than using |
1134 | @code{save-excursion} to save and restore the current buffer, is so as | |
1135 | to preserve the change in point made by the second call to | |
1136 | @code{goto-char}. | |
73804d4b RS |
1137 | |
1138 | To make the filter force the process buffer to be visible whenever new | |
1139 | text arrives, insert the following line just before the | |
f9f59935 | 1140 | @code{with-current-buffer} construct: |
73804d4b RS |
1141 | |
1142 | @smallexample | |
1143 | (display-buffer (process-buffer proc)) | |
1144 | @end smallexample | |
1145 | ||
f9f59935 RS |
1146 | To force point to the end of the new output, no matter where it was |
1147 | previously, eliminate the variable @code{moving} and call | |
73804d4b RS |
1148 | @code{goto-char} unconditionally. |
1149 | ||
f9f59935 RS |
1150 | In earlier Emacs versions, every filter function that did regular |
1151 | expression searching or matching had to explicitly save and restore the | |
1152 | match data. Now Emacs does this automatically for filter functions; | |
1153 | they never need to do it explicitly. @xref{Match Data}. | |
73804d4b RS |
1154 | |
1155 | A filter function that writes the output into the buffer of the | |
bfe721d1 | 1156 | process should check whether the buffer is still alive. If it tries to |
f9f59935 RS |
1157 | insert into a dead buffer, it will get an error. The expression |
1158 | @code{(buffer-name (process-buffer @var{process}))} returns @code{nil} | |
1159 | if the buffer is dead. | |
73804d4b RS |
1160 | |
1161 | The output to the function may come in chunks of any size. A program | |
f9f59935 RS |
1162 | that produces the same output twice in a row may send it as one batch of |
1163 | 200 characters one time, and five batches of 40 characters the next. If | |
1164 | the filter looks for certain text strings in the subprocess output, make | |
1165 | sure to handle the case where one of these strings is split across two | |
1166 | or more batches of output. | |
73804d4b RS |
1167 | |
1168 | @defun set-process-filter process filter | |
1169 | This function gives @var{process} the filter function @var{filter}. If | |
1170 | @var{filter} is @code{nil}, it gives the process no filter. | |
1171 | @end defun | |
1172 | ||
1173 | @defun process-filter process | |
1174 | This function returns the filter function of @var{process}, or @code{nil} | |
1175 | if it has none. | |
1176 | @end defun | |
1177 | ||
1178 | Here is an example of use of a filter function: | |
1179 | ||
1180 | @smallexample | |
1181 | @group | |
1182 | (defun keep-output (process output) | |
1183 | (setq kept (cons output kept))) | |
1184 | @result{} keep-output | |
1185 | @end group | |
1186 | @group | |
1187 | (setq kept nil) | |
1188 | @result{} nil | |
1189 | @end group | |
1190 | @group | |
1191 | (set-process-filter (get-process "shell") 'keep-output) | |
1192 | @result{} keep-output | |
1193 | @end group | |
1194 | @group | |
1195 | (process-send-string "shell" "ls ~/other\n") | |
1196 | @result{} nil | |
1197 | kept | |
1198 | @result{} ("lewis@@slug[8] % " | |
1199 | @end group | |
1200 | @group | |
1201 | "FINAL-W87-SHORT.MSS backup.otl kolstad.mss~ | |
1202 | address.txt backup.psf kolstad.psf | |
1203 | backup.bib~ david.mss resume-Dec-86.mss~ | |
1204 | backup.err david.psf resume-Dec.psf | |
1205 | backup.mss dland syllabus.mss | |
1206 | " | |
1207 | "#backups.mss# backup.mss~ kolstad.mss | |
1208 | ") | |
1209 | @end group | |
1210 | @end smallexample | |
1211 | ||
1212 | @ignore @c The code in this example doesn't show the right way to do things. | |
1213 | Here is another, more realistic example, which demonstrates how to use | |
1214 | the process mark to do insertion in the same fashion as is done when | |
1215 | there is no filter function: | |
1216 | ||
1217 | @smallexample | |
1218 | @group | |
1219 | ;; @r{Insert input in the buffer specified by @code{my-shell-buffer}} | |
1220 | ;; @r{and make sure that buffer is shown in some window.} | |
1221 | (defun my-process-filter (proc str) | |
f9f59935 RS |
1222 | (let ((cur (selected-window)) |
1223 | (pop-up-windows t)) | |
1224 | (pop-to-buffer my-shell-buffer) | |
73804d4b RS |
1225 | @end group |
1226 | @group | |
f9f59935 RS |
1227 | (goto-char (point-max)) |
1228 | (insert str) | |
1229 | (set-marker (process-mark proc) (point-max)) | |
1230 | (select-window cur))) | |
73804d4b RS |
1231 | @end group |
1232 | @end smallexample | |
1233 | @end ignore | |
1234 | ||
582ef186 RS |
1235 | @node Decoding Output |
1236 | @subsection Decoding Process Output | |
1237 | ||
1238 | When Emacs writes process output directly into a multibyte buffer, | |
1239 | it decodes the output according to the process output coding system. | |
1240 | If the coding system is @code{raw-text} or @code{no-conversion}, Emacs | |
1241 | converts the unibyte output to multibyte using | |
fea5a6d5 | 1242 | @code{string-to-multibyte}, and inserts the resulting multibyte text. |
582ef186 RS |
1243 | |
1244 | You can use @code{set-process-coding-system} to specify which coding | |
1245 | system to use (@pxref{Process Information}). Otherwise, the coding | |
1246 | system comes from @code{coding-system-for-read}, if that is | |
1247 | non-@code{nil}; or else from the defaulting mechanism (@pxref{Default | |
1248 | Coding Systems}). | |
1249 | ||
1250 | @strong{Warning:} Coding systems such as @code{undecided} which | |
1251 | determine the coding system from the data do not work entirely | |
1252 | reliably with asynchronous subprocess output. This is because Emacs | |
1253 | has to process asynchronous subprocess output in batches, as it | |
1254 | arrives. Emacs must try to detect the proper coding system from one | |
1255 | batch at a time, and this does not always work. Therefore, if at all | |
1256 | possible, specify a coding system that determines both the character | |
1257 | code conversion and the end of line conversion---that is, one like | |
1258 | @code{latin-1-unix}, rather than @code{undecided} or @code{latin-1}. | |
1259 | ||
1260 | @cindex filter multibyte flag, of process | |
1261 | @cindex process filter multibyte flag | |
1262 | When Emacs calls a process filter function, it provides the process | |
1263 | output as a multibyte string or as a unibyte string according to the | |
1264 | process's filter multibyte flag. If the flag is non-@code{nil}, Emacs | |
1265 | decodes the output according to the process output coding system to | |
1266 | produce a multibyte string, and passes that to the process. If the | |
1267 | flag is @code{nil}, Emacs puts the output into a unibyte string, with | |
1268 | no decoding, and passes that. | |
1269 | ||
1270 | When you create a process, the filter multibyte flag takes its | |
1271 | initial value from @code{default-enable-multibyte-characters}. If you | |
1272 | want to change the flag later on, use | |
1273 | @code{set-process-filter-multibyte}. | |
1274 | ||
1275 | @defun set-process-filter-multibyte process multibyte | |
1276 | This function sets the filter multibyte flag of @var{process} | |
1277 | to @var{multibyte}. | |
1278 | @end defun | |
1279 | ||
1280 | @defun process-filter-multibyte-p process | |
1281 | This function returns the filter multibyte flag of @var{process}. | |
1282 | @end defun | |
1283 | ||
73804d4b RS |
1284 | @node Accepting Output |
1285 | @subsection Accepting Output from Processes | |
1286 | ||
1287 | Output from asynchronous subprocesses normally arrives only while | |
1288 | Emacs is waiting for some sort of external event, such as elapsed time | |
1289 | or terminal input. Occasionally it is useful in a Lisp program to | |
1290 | explicitly permit output to arrive at a specific point, or even to wait | |
1291 | until output arrives from a process. | |
1292 | ||
410bcc31 | 1293 | @defun accept-process-output &optional process seconds millisec just-this-one |
73804d4b RS |
1294 | This function allows Emacs to read pending output from processes. The |
1295 | output is inserted in the associated buffers or given to their filter | |
1296 | functions. If @var{process} is non-@code{nil} then this function does | |
1297 | not return until some output has been received from @var{process}. | |
1298 | ||
1299 | @c Emacs 19 feature | |
1300 | The arguments @var{seconds} and @var{millisec} let you specify timeout | |
1301 | periods. The former specifies a period measured in seconds and the | |
1302 | latter specifies one measured in milliseconds. The two time periods | |
1303 | thus specified are added together, and @code{accept-process-output} | |
1304 | returns after that much time whether or not there has been any | |
1305 | subprocess output. | |
1306 | ||
bfe721d1 KH |
1307 | The argument @var{seconds} need not be an integer. If it is a floating |
1308 | point number, this function waits for a fractional number of seconds. | |
1309 | Some systems support only a whole number of seconds; on these systems, | |
1911e6e5 | 1310 | @var{seconds} is rounded down. |
bfe721d1 | 1311 | |
73804d4b RS |
1312 | Not all operating systems support waiting periods other than multiples |
1313 | of a second; on those that do not, you get an error if you specify | |
1314 | nonzero @var{millisec}. | |
1315 | ||
bf247b6e | 1316 | @c Emacs 22.1 feature |
410bcc31 | 1317 | If @var{process} is a process, and the argument @var{just-this-one} is |
c1aa4864 | 1318 | non-@code{nil}, only output from that process is handled, suspending output |
410bcc31 KS |
1319 | from other processes until some output has been received from that |
1320 | process or the timeout expires. If @var{just-this-one} is an integer, | |
1321 | also inhibit running timers. This feature is generally not | |
1322 | recommended, but may be necessary for specific applications, such as | |
1323 | speech synthesis. | |
1324 | ||
73804d4b RS |
1325 | The function @code{accept-process-output} returns non-@code{nil} if it |
1326 | did get some output, or @code{nil} if the timeout expired before output | |
1327 | arrived. | |
1328 | @end defun | |
1329 | ||
1330 | @node Sentinels | |
1331 | @section Sentinels: Detecting Process Status Changes | |
1332 | @cindex process sentinel | |
1333 | @cindex sentinel | |
1334 | ||
1335 | A @dfn{process sentinel} is a function that is called whenever the | |
1336 | associated process changes status for any reason, including signals | |
1337 | (whether sent by Emacs or caused by the process's own actions) that | |
5517ea8a RS |
1338 | terminate, stop, or continue the process. The process sentinel is |
1339 | also called if the process exits. The sentinel receives two | |
1340 | arguments: the process for which the event occurred, and a string | |
1341 | describing the type of event. | |
73804d4b RS |
1342 | |
1343 | The string describing the event looks like one of the following: | |
1344 | ||
1345 | @itemize @bullet | |
177c0ea7 | 1346 | @item |
73804d4b RS |
1347 | @code{"finished\n"}. |
1348 | ||
1349 | @item | |
1350 | @code{"exited abnormally with code @var{exitcode}\n"}. | |
1351 | ||
1352 | @item | |
1353 | @code{"@var{name-of-signal}\n"}. | |
1354 | ||
1355 | @item | |
1356 | @code{"@var{name-of-signal} (core dumped)\n"}. | |
1357 | @end itemize | |
1358 | ||
5517ea8a RS |
1359 | A sentinel runs only while Emacs is waiting (e.g., for terminal |
1360 | input, or for time to elapse, or for process output). This avoids the | |
1361 | timing errors that could result from running them at random places in | |
1362 | the middle of other Lisp programs. A program can wait, so that | |
1363 | sentinels will run, by calling @code{sit-for} or @code{sleep-for} | |
78608595 | 1364 | (@pxref{Waiting}), or @code{accept-process-output} (@pxref{Accepting |
a9f0a989 | 1365 | Output}). Emacs also allows sentinels to run when the command loop is |
5517ea8a RS |
1366 | reading input. @code{delete-process} calls the sentinel when it |
1367 | terminates a running process. | |
1368 | ||
1369 | Emacs does not keep a queue of multiple reasons to call the sentinel | |
1370 | of one process; it records just the current status and the fact that | |
1371 | there has been a change. Therefore two changes in status, coming in | |
1372 | quick succession, can call the sentinel just once. However, process | |
1373 | termination will always run the sentinel exactly once. This is | |
1374 | because the process status can't change again after termination. | |
73804d4b RS |
1375 | |
1376 | Quitting is normally inhibited within a sentinel---otherwise, the | |
1377 | effect of typing @kbd{C-g} at command level or to quit a user command | |
1378 | would be unpredictable. If you want to permit quitting inside a | |
1379 | sentinel, bind @code{inhibit-quit} to @code{nil}. @xref{Quitting}. | |
1380 | ||
1381 | A sentinel that writes the output into the buffer of the process | |
bfe721d1 | 1382 | should check whether the buffer is still alive. If it tries to insert |
73804d4b RS |
1383 | into a dead buffer, it will get an error. If the buffer is dead, |
1384 | @code{(buffer-name (process-buffer @var{process}))} returns @code{nil}. | |
1385 | ||
22697dac KH |
1386 | If an error happens during execution of a sentinel, it is caught |
1387 | automatically, so that it doesn't stop the execution of whatever | |
1388 | programs was running when the sentinel was started. However, if | |
1389 | @code{debug-on-error} is non-@code{nil}, the error-catching is turned | |
1390 | off. This makes it possible to use the Lisp debugger to debug the | |
1391 | sentinel. @xref{Debugger}. | |
1392 | ||
8a56d8ed RS |
1393 | While a sentinel is running, the process sentinel is temporarily |
1394 | set to @code{nil} so that the sentinel won't run recursively. | |
1395 | For this reason it is not possible for a sentinel to specify | |
1396 | a new sentinel. | |
1397 | ||
f9f59935 RS |
1398 | In earlier Emacs versions, every sentinel that did regular expression |
1399 | searching or matching had to explicitly save and restore the match data. | |
1400 | Now Emacs does this automatically for sentinels; they never need to do | |
1401 | it explicitly. @xref{Match Data}. | |
bfe721d1 | 1402 | |
73804d4b RS |
1403 | @defun set-process-sentinel process sentinel |
1404 | This function associates @var{sentinel} with @var{process}. If | |
1405 | @var{sentinel} is @code{nil}, then the process will have no sentinel. | |
1406 | The default behavior when there is no sentinel is to insert a message in | |
1407 | the process's buffer when the process status changes. | |
1408 | ||
5517ea8a RS |
1409 | Changes in process sentinel take effect immediately---if the sentinel |
1410 | is slated to be run but has not been called yet, and you specify a new | |
1411 | sentinel, the eventual call to the sentinel will use the new one. | |
1412 | ||
73804d4b RS |
1413 | @smallexample |
1414 | @group | |
1415 | (defun msg-me (process event) | |
1416 | (princ | |
1417 | (format "Process: %s had the event `%s'" process event))) | |
1418 | (set-process-sentinel (get-process "shell") 'msg-me) | |
1419 | @result{} msg-me | |
1420 | @end group | |
1421 | @group | |
1422 | (kill-process (get-process "shell")) | |
1423 | @print{} Process: #<process shell> had the event `killed' | |
1424 | @result{} #<process shell> | |
1425 | @end group | |
1426 | @end smallexample | |
1427 | @end defun | |
1428 | ||
1429 | @defun process-sentinel process | |
1430 | This function returns the sentinel of @var{process}, or @code{nil} if it | |
1431 | has none. | |
1432 | @end defun | |
1433 | ||
1434 | @defun waiting-for-user-input-p | |
1435 | While a sentinel or filter function is running, this function returns | |
1436 | non-@code{nil} if Emacs was waiting for keyboard input from the user at | |
1437 | the time the sentinel or filter function was called, @code{nil} if it | |
1438 | was not. | |
1439 | @end defun | |
1440 | ||
edc590bb | 1441 | @node Query Before Exit |
177c0ea7 | 1442 | @section Querying Before Exit |
edc590bb RS |
1443 | |
1444 | When Emacs exits, it terminates all its subprocesses by sending them | |
fea5a6d5 | 1445 | the @code{SIGHUP} signal. Because subprocesses may be doing |
edc590bb RS |
1446 | valuable work, Emacs normally asks the user to confirm that it is ok |
1447 | to terminate them. Each process has a query flag which, if | |
1448 | non-@code{nil}, says that Emacs should ask for confirmation before | |
1449 | exiting and thus killing that process. The default for the query flag | |
1450 | is @code{t}, meaning @emph{do} query. | |
1451 | ||
1452 | @tindex process-query-on-exit-flag | |
1453 | @defun process-query-on-exit-flag process | |
1454 | This returns the query flag of @var{process}. | |
1455 | @end defun | |
1456 | ||
1457 | @tindex set-process-query-on-exit-flag | |
1458 | @defun set-process-query-on-exit-flag process flag | |
1459 | This function sets the query flag of @var{process} to @var{flag}. It | |
1460 | returns @var{flag}. | |
1461 | ||
1462 | @smallexample | |
1463 | @group | |
1464 | ;; @r{Don't query about the shell process} | |
1465 | (set-process-query-on-exit-flag (get-process "shell") nil) | |
1466 | @result{} t | |
1467 | @end group | |
1468 | @end smallexample | |
1469 | @end defun | |
1470 | ||
1471 | @defun process-kill-without-query process &optional do-query | |
1472 | This function clears the query flag of @var{process}, so that | |
1473 | Emacs will not query the user on account of that process. | |
1474 | ||
1475 | Actually, the function does more than that: it returns the old value of | |
1476 | the process's query flag, and sets the query flag to @var{do-query}. | |
1477 | Please don't use this function to do those things any more---please | |
1478 | use the newer, cleaner functions @code{process-query-on-exit-flag} and | |
1479 | @code{set-process-query-on-exit-flag} in all but the simplest cases. | |
1480 | The only way you should use @code{process-kill-without-query} nowadays | |
1481 | is like this: | |
1482 | ||
1483 | @smallexample | |
1484 | @group | |
1485 | ;; @r{Don't query about the shell process} | |
1486 | (process-kill-without-query (get-process "shell")) | |
1487 | @end group | |
1488 | @end smallexample | |
1489 | @end defun | |
1490 | ||
73804d4b RS |
1491 | @node Transaction Queues |
1492 | @section Transaction Queues | |
1493 | @cindex transaction queue | |
1494 | ||
f9f59935 RS |
1495 | You can use a @dfn{transaction queue} to communicate with a subprocess |
1496 | using transactions. First use @code{tq-create} to create a transaction | |
1497 | queue communicating with a specified process. Then you can call | |
1498 | @code{tq-enqueue} to send a transaction. | |
73804d4b RS |
1499 | |
1500 | @defun tq-create process | |
1501 | This function creates and returns a transaction queue communicating with | |
1502 | @var{process}. The argument @var{process} should be a subprocess | |
1503 | capable of sending and receiving streams of bytes. It may be a child | |
78608595 | 1504 | process, or it may be a TCP connection to a server, possibly on another |
73804d4b RS |
1505 | machine. |
1506 | @end defun | |
1507 | ||
1508 | @defun tq-enqueue queue question regexp closure fn | |
1509 | This function sends a transaction to queue @var{queue}. Specifying the | |
1510 | queue has the effect of specifying the subprocess to talk to. | |
1511 | ||
78608595 | 1512 | The argument @var{question} is the outgoing message that starts the |
73804d4b RS |
1513 | transaction. The argument @var{fn} is the function to call when the |
1514 | corresponding answer comes back; it is called with two arguments: | |
1515 | @var{closure}, and the answer received. | |
1516 | ||
6f6fd5ef RS |
1517 | The argument @var{regexp} is a regular expression that should match |
1518 | text at the end of the entire answer, but nothing before; that's how | |
1519 | @code{tq-enqueue} determines where the answer ends. | |
73804d4b RS |
1520 | |
1521 | The return value of @code{tq-enqueue} itself is not meaningful. | |
1522 | @end defun | |
1523 | ||
1524 | @defun tq-close queue | |
1525 | Shut down transaction queue @var{queue}, waiting for all pending transactions | |
1526 | to complete, and then terminate the connection or child process. | |
1527 | @end defun | |
1528 | ||
1529 | Transaction queues are implemented by means of a filter function. | |
1530 | @xref{Filter Functions}. | |
1531 | ||
bfe721d1 KH |
1532 | @node Network |
1533 | @section Network Connections | |
1534 | @cindex network connection | |
73804d4b | 1535 | @cindex TCP |
0bbffed7 | 1536 | @cindex UDP |
73804d4b | 1537 | |
0bbffed7 KS |
1538 | Emacs Lisp programs can open stream (TCP) and datagram (UDP) network |
1539 | connections to other processes on the same machine or other machines. | |
1540 | A network connection is handled by Lisp much like a subprocess, and is | |
4bb24054 RS |
1541 | represented by a process object. However, the process you are |
1542 | communicating with is not a child of the Emacs process, so it has no | |
ad800164 | 1543 | process @acronym{ID}, and you can't kill it or send it signals. All you |
4bb24054 RS |
1544 | can do is send and receive data. @code{delete-process} closes the |
1545 | connection, but does not kill the program at the other end; that | |
1546 | program must decide what to do about closure of the connection. | |
1547 | ||
1548 | Lisp programs can listen for connections by creating network | |
1549 | servers. A network server is also represented by a kind of process | |
1550 | object, but unlike a network connection, the network server never | |
1551 | transfers data itself. When it receives a connection request, it | |
1552 | creates a new network connection to represent the connection just | |
1553 | made. (The network connection inherits certain information, including | |
1554 | the process plist, from the server.) The network server then goes | |
1555 | back to listening for more connection requests. | |
73804d4b | 1556 | |
78e54e2d KS |
1557 | Network connections and servers are created by calling |
1558 | @code{make-network-process} with an argument list consisting of | |
1559 | keyword/argument pairs, for example @code{:server t} to create a | |
1560 | server process, or @code{:type 'datagram} to create a datagram | |
30f4318d | 1561 | connection. @xref{Low-Level Network}, for details. You can also use |
78e54e2d KS |
1562 | one of the @code{open-network-...} functions descibed below; |
1563 | internally, they just call @code{make-network-process} with suitable | |
1564 | arguments. | |
1565 | ||
73804d4b | 1566 | You can distinguish process objects representing network connections |
4bb24054 RS |
1567 | and servers from those representing subprocesses with the |
1568 | @code{process-status} function. The possible status values for | |
1569 | network connections are @code{open}, @code{closed}, @code{connect}, | |
1570 | and @code{failed}. For a network server, the status is always | |
1571 | @code{listen}. None of those values is possible for a real | |
1572 | subprocess. @xref{Process Information}. | |
1573 | ||
38e82e48 | 1574 | You can stop and resume operation of a network process by calling |
4bb24054 RS |
1575 | @code{stop-process} and @code{continue-process}. For a server |
1576 | process, being stopped means not accepting new connections. (Up to 5 | |
0bbffed7 KS |
1577 | connection requests will be queued for when you resume the server; you |
1578 | can increase this limit, unless it is imposed by the operating | |
312660e0 | 1579 | systems.) For a network stream connection, being stopped means not |
0bbffed7 | 1580 | processing input (any arriving input waits until you resume the |
312660e0 RS |
1581 | connection). For a datagram connection, some number of packets may be |
1582 | queued but input may be lost. You can use the function | |
1583 | @code{process-command} to determine whether a network connection or | |
1584 | server is stopped; a non-@code{nil} value means yes. | |
73804d4b RS |
1585 | |
1586 | @defun open-network-stream name buffer-or-name host service | |
4bb24054 RS |
1587 | This function opens a TCP connection, and returns a process object |
1588 | that represents the connection. | |
73804d4b RS |
1589 | |
1590 | The @var{name} argument specifies the name for the process object. It | |
1591 | is modified as necessary to make it unique. | |
1592 | ||
1593 | The @var{buffer-or-name} argument is the buffer to associate with the | |
1594 | connection. Output from the connection is inserted in the buffer, | |
1595 | unless you specify a filter function to handle the output. If | |
1596 | @var{buffer-or-name} is @code{nil}, it means that the connection is not | |
1597 | associated with any buffer. | |
1598 | ||
1599 | The arguments @var{host} and @var{service} specify where to connect to; | |
1600 | @var{host} is the host name (a string), and @var{service} is the name of | |
1601 | a defined network service (a string) or a port number (an integer). | |
1602 | @end defun | |
ab5796a9 | 1603 | |
4bb24054 RS |
1604 | @defun open-network-stream-nowait name buffer-or-name host service &optional sentinel filter |
1605 | This function opens a TCP connection, like @code{open-network-stream}, | |
1606 | but it returns immediately without waiting for the request to be | |
1607 | accepted or rejected by the remote server. When the request is | |
1608 | subsequently accepted or rejected, the process's sentinel function | |
1609 | will be called with a string that starts with @code{"open"} (on | |
1610 | success) or @code{"failed"} (on error). | |
1611 | ||
1612 | Some systems do not support non-blocking connections; on those | |
1613 | systems, @code{open-network-stream-nowait} returns @code{nil} | |
1614 | and does nothing. | |
1615 | ||
1616 | The optional arguments @var{sentinel} and @var{filter} specify the | |
1617 | sentinel and filter functions for this network connection. It is | |
1618 | useful to specify them when opening the connection, because they will | |
1619 | be used later asynchronously. The other arguments mean the same as in | |
1620 | @code{open-network-stream}. | |
1621 | @end defun | |
1622 | ||
1623 | @defun process-contact process &optional key | |
1624 | This function returns information about how a network process was set | |
1625 | up. For a connection, when @var{key} is @code{nil}, it returns | |
1626 | @code{(@var{hostname} @var{service})} which specifies what you | |
1627 | connected to. | |
1628 | ||
1629 | If @var{key} is @code{t}, the value is the complete status information | |
1630 | for the connection or server; that is, the list of keywords and values | |
1631 | specified in @code{make-network-process}, except that some of the | |
1632 | values represent the current status instead of what you specified: | |
1633 | ||
1634 | @table @code | |
1635 | @item :buffer | |
1636 | The associated value is the process buffer. | |
1637 | @item :filter | |
1638 | The associated value is the process filter function. | |
1639 | @item :sentinel | |
0bbffed7 | 1640 | The associated value is the process sentinel function. |
4bb24054 RS |
1641 | @item :remote |
1642 | In a connection, this is the address in internal format of the remote peer. | |
1643 | @item :local | |
1644 | The local address, in internal format. | |
1645 | @item :service | |
1646 | In a server, if you specified @code{t} for @var{service}, | |
1647 | this value is the actual port number. | |
1648 | @end table | |
1649 | ||
1650 | @code{:local} and @code{:remote} are included even if they were not | |
1651 | specified explicitly in @code{make-network-process}. | |
1652 | ||
1653 | If @var{key} is a keyword, the function returns the value corresponding | |
1654 | to that keyword. | |
1655 | ||
1656 | For an ordinary child process, this function always returns @code{t}. | |
1657 | @end defun | |
1658 | ||
1659 | @node Network Servers | |
1660 | @section Network Servers | |
1661 | ||
1662 | You create a server by calling @code{make-network-process} with | |
1663 | @code{:server t}. The server will listen for connection requests from | |
1664 | clients. When it accepts a client connection request, that creates a | |
1665 | new network connection, itself a process object, with the following | |
1666 | parameters: | |
1667 | ||
1668 | @itemize @bullet | |
1669 | @item | |
1670 | The connection's process name is constructed by concatenating the | |
1671 | server process' @var{name} with a client identification string. The | |
1672 | client identification string for an IPv4 connection looks like | |
1673 | @samp{<@var{a}.@var{b}.@var{c}.@var{d}:@var{p}>}. Otherwise, it is a | |
0bbffed7 | 1674 | unique number in brackets, as in @samp{<@var{nnn}>}. The number |
4bb24054 RS |
1675 | is unique for each connection in the Emacs session. |
1676 | ||
1677 | @item | |
1678 | If the server's filter is non-@code{nil}, the connection process does | |
0bbffed7 | 1679 | not get a separate process buffer; otherwise, Emacs creates a new |
4bb24054 RS |
1680 | buffer for the purpose. The buffer name is the server's buffer name |
1681 | or process name, concatenated with the client identification string. | |
1682 | ||
1683 | The server's process buffer value is never used directly by Emacs, but | |
1684 | it is passed to the log function, which can log connections by | |
1685 | inserting text there. | |
1686 | ||
1687 | @item | |
1688 | The communication type and the process filter and sentinel are | |
1689 | inherited from those of the server. The server never directly | |
1690 | uses its filter and sentinel; their sole purpose is to initialize | |
1691 | connections made to the server. | |
1692 | ||
1693 | @item | |
1694 | The connection's process contact info is set according to the client's | |
1695 | addressing information (typically an IP address and a port number). | |
1696 | This information is associated with the @code{process-contact} | |
1697 | keywords @code{:host}, @code{:service}, @code{:remote}. | |
1698 | ||
1699 | @item | |
1700 | The connection's local address is set up according to the port | |
1701 | number used for the connection. | |
1702 | ||
1703 | @item | |
1704 | The client process' plist is initialized from the server's plist. | |
1705 | @end itemize | |
1706 | ||
1707 | @defun open-network-stream-server name buffer-or-name service &optional sentinel filter | |
1708 | Create a network server process for a TCP service. | |
00991494 | 1709 | It returns @code{nil} if server processes are not supported; otherwise, |
4bb24054 RS |
1710 | it returns a subprocess-object to represent the server. |
1711 | ||
1712 | When a client connects to the specified service, Emacs creates a new | |
1713 | subprocess to handle the new connection, and then calls its sentinel | |
1714 | function (which it has inherited from the server). | |
1715 | ||
1716 | The optional arguments @var{sentinel} and @var{filter} specify the | |
1717 | sentinel and filter functions for the server. It is useful to specify | |
1718 | them now, because they will be used later asynchronously when the | |
1719 | server receives a connection request. The three arguments @var{name}, | |
1720 | @var{buffer-or-name} and @var{service} mean the same thing as in | |
1721 | @code{open-network-stream}, but @var{service} can be @code{t} | |
1722 | meaning ask the system to allocate an unused port to listen on. | |
1723 | @end defun | |
1724 | ||
1725 | @node Datagrams | |
410bcc31 | 1726 | @section Datagrams |
4bb24054 RS |
1727 | @cindex datagrams |
1728 | ||
38e82e48 RS |
1729 | A datagram connection communicates with individual packets rather |
1730 | than streams of data. Each call to @code{process-send} sends one | |
1731 | datagram packet (@pxref{Input to Processes}), and each datagram | |
1732 | received results in one call to the filter function. | |
4bb24054 RS |
1733 | |
1734 | The datagram connection doesn't have to talk with the same remote | |
1735 | peer all the time. It has a @dfn{remote peer address} which specifies | |
1736 | where to send datagrams to. Each time an incoming datagram is passed | |
1737 | to the filter function, the peer address is set to the address that | |
1738 | datagram came from; that way, if the filter function sends a datagram, | |
1739 | it will go back to that place. You can specify the remote peer | |
1740 | address when you create the datagram connection using the | |
1741 | @code{:remote} keyword. You can change it later on by calling | |
1742 | @code{set-process-datagram-address}. | |
1743 | ||
1744 | @defun process-datagram-address process | |
1745 | If @var{process} is a datagram connection or server, this function | |
1746 | returns its remote peer address. | |
1747 | @end defun | |
1748 | ||
1749 | @defun set-process-datagram-address process address | |
1750 | If @var{process} is a datagram connection or server, this function | |
1751 | sets its remote peer address to @var{address}. | |
1752 | @end defun | |
1753 | ||
1754 | @node Low-Level Network | |
1755 | @section Low-Level Network Access | |
1756 | ||
1757 | The basic function for creating network connections and network | |
1758 | servers is @code{make-network-process}. It can do either of those | |
1759 | jobs, depending on the arguments you give it. | |
1760 | ||
1761 | @defun make-network-process &rest args | |
1762 | This function creates a network connection or server and returns the | |
1763 | process object that represents it. The arguments @var{args} are a | |
1764 | list of keyword/argument pairs. Omitting a keyword is always | |
1765 | equivalent to specifying it with value @code{nil}, except for | |
0bbffed7 KS |
1766 | @code{:coding}, @code{:filter-multibyte}, and @code{:reuseaddr}. Here |
1767 | are the meaningful keywords: | |
4bb24054 RS |
1768 | |
1769 | @table @asis | |
1770 | @item :name name | |
1771 | Use the string @var{name} as the process name. It is modified if | |
1772 | necessary to make it unique. | |
1773 | ||
1774 | @item :type @var{type} | |
1775 | Specify the communication type. A value of @code{nil} specifies a | |
1776 | stream connection (the default); @code{datagram} specifies a datagram | |
1777 | connection. Both connections and servers can be of either type. | |
1778 | ||
1779 | @item :server @var{server-flag} | |
1780 | If @var{server-flag} is non-@code{nil}, create a server. Otherwise, | |
0bbffed7 KS |
1781 | create a connection. For a stream type server, @var{server-flag} may |
1782 | be an integer which then specifies the length of the queue of pending | |
1783 | connections to the server. The default queue length is 5. | |
4bb24054 RS |
1784 | |
1785 | @item :host @var{host} | |
1786 | Specify the host to connect to. @var{host} should be a host name or | |
1787 | internet address, as a string, or the symbol @code{local} to specify | |
1788 | the local host. If you specify @var{host} for a server, it must | |
1789 | specify a valid address for the local host, and only clients | |
1790 | connecting to that address will be accepted. | |
1791 | ||
1792 | @item :service @var{service} | |
1793 | @var{service} specifies a port number to connect to, or, for a server, | |
1794 | the port number to listen on. It should be a service name that | |
1795 | translates to a port number, or an integer specifying the port number | |
1796 | directly. For a server, it can also be @code{t}, which means to let | |
1797 | the system select an unused port number. | |
1798 | ||
1799 | @item :family @var{family} | |
1800 | @var{family} specifies the address (and protocol) family for | |
1801 | communication. @code{nil} stands for IPv4. @code{local} specifies a | |
1802 | Unix socket, in which case @var{host} is ignored. | |
1803 | ||
1804 | @item :local @var{local-address} | |
1805 | For a server process, @var{local-address} is the address to listen on. | |
1806 | It overrides @var{family}, @var{host} and @var{service}, and you | |
1807 | may as well not specify them. | |
1808 | ||
1809 | @item :remote @var{remote-address} | |
1810 | For a connection, @var{remote-address} is the address to connect to. | |
1811 | It overrides @var{family}, @var{host} and @var{service}, and you | |
1812 | may as well not specify them. | |
1813 | ||
1814 | For a datagram server, @var{remote-address} specifies the initial | |
1815 | setting of the remote datagram address. | |
1816 | ||
1817 | The format of @var{local-address} or @var{remote-address} depends on | |
1818 | the address family: | |
1819 | ||
1820 | @itemize - | |
1821 | @item | |
1822 | An IPv4 address is represented as a vector of integers @code{[@var{a} | |
1823 | @var{b} @var{c} @var{d} @var{p}]} corresponding to numeric IP address | |
1824 | @var{a}.@var{b}.@var{c}.@var{d} and port number @var{p}. | |
1825 | ||
1826 | @item | |
1827 | A local address is represented as a string which specifies the address | |
1828 | in the local address space. | |
1829 | ||
1830 | @item | |
1831 | An ``unsupported family'' address is represented by a cons | |
1832 | @code{(@var{f} . @var{av})}, where @var{f} is the family number and | |
38e82e48 RS |
1833 | @var{av} is a vector specifying the socket address using one element |
1834 | per address data byte. Do not rely on this format in portable code, | |
1835 | as it may depend on implementation defined constants, data sizes, and | |
1836 | data structure alignment. | |
4bb24054 RS |
1837 | @end itemize |
1838 | ||
1839 | @item :nowait @var{bool} | |
1840 | If @var{bool} is non-@code{nil} for a stream connection, return | |
1841 | without waiting for the connection to complete. When the connection | |
1842 | succeeds or fails, Emacs will call the sentinel function, with a | |
1843 | second argument matching @code{"open"} (if successful) or | |
1844 | @code{"failed"}. The default is to block, so that | |
1845 | @code{make-network-process} does not return until the connection | |
1846 | has succeeded or failed. | |
1847 | ||
1848 | @item :stop @var{stopped} | |
1849 | Start the network connection or server in the `stopped' state if | |
1850 | @var{stopped} is non-@code{nil}. | |
1851 | ||
1852 | @item :buffer @var{buffer} | |
1853 | Use @var{buffer} as the process buffer. | |
1854 | ||
1855 | @item :coding @var{coding} | |
1856 | Use @var{coding} as the coding system for this process. To specify | |
1857 | different coding systems for decoding data from the connection and for | |
1858 | encoding data sent to it, specify @code{(@var{decoding} . | |
1859 | @var{encoding})} for @var{coding}. | |
1860 | ||
1861 | If you don't specify this keyword at all, the default | |
0bbffed7 | 1862 | is to determine the coding systems from the data. |
4bb24054 RS |
1863 | |
1864 | @item :noquery @var{query-flag} | |
0bbffed7 | 1865 | Initialize the process query flag to @var{query-flag}. @xref{Query Before Exit}. |
4bb24054 RS |
1866 | |
1867 | @item :filter @var{filter} | |
1868 | Initialize the process filter to @var{filter}. | |
1869 | ||
1870 | @item :filter-multibyte @var{bool} | |
1871 | If @var{bool} is non-@code{nil}, strings given to the process filter | |
1872 | are multibyte, otherwise they are unibyte. If you don't specify this | |
1873 | keyword at all, the default is that the strings are multibyte if | |
1874 | @code{default-enable-multibyte-characters} is non-@code{nil}. | |
1875 | ||
1876 | @item :sentinel @var{sentinel} | |
1877 | Initialize the process sentinel to @var{sentinel}. | |
1878 | ||
1879 | @item :log @var{log} | |
1880 | Initialize the log function of a server process to @var{log}. The log | |
1881 | function is called each time the server accepts a network connection | |
1882 | from a client. The arguments passed to the log function are | |
1883 | @var{server}, @var{connection}, and @var{message}, where @var{server} | |
1884 | is the server process, @var{connection} is the new process for the | |
1885 | connection, and @var{message} is a string describing what has | |
1886 | happened. | |
1887 | ||
1888 | @item :plist @var{plist} | |
1889 | Initialize the process plist to @var{plist}. | |
1890 | @end table | |
1891 | ||
0bbffed7 KS |
1892 | The following network options can be specified for the network |
1893 | process. Except for @code{:reuseaddr}, you can set or modify these | |
1894 | options later using @code{set-network-process-option}. | |
1895 | ||
1896 | For a server process, the options specified with | |
1897 | @code{make-network-process} are not inherited by the client | |
1898 | connections, so you will need to set the necessary options for each | |
1899 | child connection as they are created. | |
1900 | ||
41beda59 | 1901 | @table @asis |
0bbffed7 KS |
1902 | @item :bindtodevice @var{device-name} |
1903 | If @var{device-name} is a non-empty string identifying a network | |
1904 | interface name (see @code{network-interface-list}), only handle | |
00991494 JH |
1905 | packets received on that interface. If @var{device-name} is @code{nil} |
1906 | (the default), handle packets received on any interface. | |
0bbffed7 KS |
1907 | |
1908 | Using this option may require special privileges on some systems. | |
1909 | ||
1910 | @item :broadcast @var{broadcast-flag} | |
1911 | If @var{broadcast-flag} is non-@code{nil} for a datagram process, the | |
1912 | process will receive datagram packet sent to a broadcast address, and | |
1913 | be able to send packets to a broadcast address. Ignored for a stream | |
1914 | connection. | |
1915 | ||
1916 | @item :dontroute @var{dontroute-flag} | |
1917 | If @var{dontroute-flag} is non-@code{nil}, the process can only send | |
1918 | to hosts on the same network as the local host. | |
1919 | ||
1920 | @item :keepalive @var{keepalive-flag} | |
1921 | If @var{keepalive-flag} is non-@code{nil} for a stream connection, | |
491cd154 | 1922 | enable exchange of low-level keep-alive messages. |
0bbffed7 KS |
1923 | |
1924 | @item :linger @var{linger-arg} | |
1925 | If @var{linger-arg} is non-@code{nil}, wait for successful | |
1926 | transmission of all queued packets on the connection before it is | |
1927 | deleted (see @code{delete-process}). If @var{linger-arg} is an | |
1928 | integer, it specifies the maximum time in seconds to wait for queued | |
1929 | packets to be sent before closing the connection. Default is | |
1930 | @code{nil} which means to discard unsent queued packets when the | |
1931 | process is deleted. | |
1932 | ||
1933 | @item :oobinline @var{oobinline-flag} | |
1934 | If @var{oobinline-flag} is non-@code{nil} for a stream connection, | |
1935 | receive out-of-band data in the normal data stream. Otherwise, ignore | |
1936 | out-of-band data. | |
1937 | ||
1938 | @item :priority @var{priority} | |
1939 | Set the priority for packets sent on this connection to the integer | |
1940 | @var{priority}. The interpretation of this number is protocol | |
1941 | specific, such as setting the TOS (type of service) field on IP | |
1942 | packets sent on this connection. It may also have system dependent | |
1943 | effects, such as selecting a specific output queue on the network | |
1944 | interface. | |
1945 | ||
1946 | @item :reuseaddr @var{reuseaddr-flag} | |
1947 | If @var{reuseaddr-flag} is non-@code{nil} (the default) for a stream | |
1948 | server process, allow this server to reuse a specific port number (see | |
1949 | @code{:service}) unless another process on this host is already | |
1950 | listening on that port. If @var{reuseaddr-flag} is @code{nil}, there | |
1951 | may be a period of time after the last use of that port (by any | |
1952 | process on the host), where it is not possible to make a new server on | |
1953 | that port. | |
1954 | ||
1955 | @end table | |
1956 | ||
4bb24054 | 1957 | The original argument list, modified with the actual connection |
f3544d11 | 1958 | information, is available via the @code{process-contact} function. |
4bb24054 RS |
1959 | @end defun |
1960 | ||
0bbffed7 KS |
1961 | @defun set-network-process-option process option value |
1962 | This function sets or modifies a network option for network process | |
1963 | @var{process}. See @code{make-network-process} for details of options | |
1964 | @var{option} and their corresponding values @var{value}. | |
1965 | ||
1966 | The current setting of an option is available via the | |
f3544d11 | 1967 | @code{process-contact} function. |
0bbffed7 KS |
1968 | @end defun |
1969 | ||
4bb24054 RS |
1970 | @defun network-interface-list |
1971 | This function returns a list describing the network interfaces | |
1972 | of the machine you are using. The value is an alist whose | |
1973 | elements have the form @code{(@var{name} . @var{address})}. | |
1974 | @var{address} has the same form as the @var{local-address} | |
1975 | and @var{remote-address} arguments to @code{make-network-process}. | |
1976 | @end defun | |
1977 | ||
1978 | @defun network-interface-info ifname | |
1979 | This function returns information about the network interface named | |
1980 | @var{ifname}. The value is a list of the form @code{(@var{addr} @var{bcast} @var{netmask} @var{hwaddr} @var{flags})}. | |
1981 | ||
1982 | @table @var | |
1983 | @item addr | |
1984 | The internet protocol address. | |
1985 | @item bcast | |
1986 | The broadcast address. | |
1987 | @item netmask | |
1988 | The network mask. | |
1989 | @item hwaddr | |
1990 | The layer 2 address (Ethernet MAC address, for instance). | |
1991 | @item flags | |
1992 | The current flags of the interface. | |
1993 | @end table | |
1994 | @end defun | |
1995 | ||
1996 | @defun format-network-address address &optional omit-port | |
bb3edd15 | 1997 | This function converts the Lisp representation of a network address to |
4bb24054 RS |
1998 | a string. For example, a five-element vector @code{[@var{a} @var{b} |
1999 | @var{c} @var{d} @var{p}]} represents an IP address | |
2000 | @var{a}.@var{b}.@var{c}.@var{d} and port number @var{p}. | |
2001 | @code{format-network-address} converts that to the string | |
2002 | @code{"@var{a}.@var{b}.@var{c}.@var{d}:@var{p}"}. | |
2003 | ||
2004 | If @var{omit-port} is non-@code{nil}, the value does not include | |
2005 | the port number. | |
2006 | @end defun | |
2007 | ||
2008 | To test for the availability of a given network feature, use | |
2009 | @code{featurep} like this: | |
2010 | ||
2011 | @example | |
2012 | (featurep 'make-network-process '(@var{keyword} @var{value})) | |
410bcc31 | 2013 | @end example |
4bb24054 RS |
2014 | |
2015 | @noindent | |
0bbffed7 KS |
2016 | The result of the first form is @code{t} if it works to specify |
2017 | @var{keyword} with value @var{value} in @code{make-network-process}. | |
2018 | The result of the second form is @code{t} if @var{keyword} is | |
2019 | supported by @code{make-network-process}. Here are some of the | |
2020 | @var{keyword}---@var{value} pairs you can test in | |
2021 | this way. | |
4bb24054 RS |
2022 | |
2023 | @table @code | |
2024 | @item (:nowait t) | |
2025 | Non-@code{nil} if non-blocking connect is supported. | |
2026 | @item (:type datagram) | |
2027 | Non-@code{nil} if datagrams are supported. | |
2028 | @item (:family local) | |
2029 | Non-@code{nil} if local (aka ``UNIX domain'') sockets are supported. | |
2030 | @item (:service t) | |
2031 | Non-@code{nil} if the system can select the port for a server. | |
0bbffed7 KS |
2032 | @end table |
2033 | ||
2034 | To test for the availability of a given network option, use | |
2035 | @code{featurep} like this: | |
2036 | ||
2037 | @example | |
2038 | (featurep 'make-network-process '@var{keyword}) | |
410bcc31 | 2039 | @end example |
0bbffed7 KS |
2040 | |
2041 | Here are some of the option @var{keyword}s you can test in | |
2042 | this way. | |
2043 | ||
2044 | @table @code | |
2045 | @item :bindtodevice | |
2046 | @itemx :broadcast | |
2047 | @itemx :dontroute | |
2048 | @itemx :keepalive | |
2049 | @itemx :linger | |
2050 | @itemx :oobinline | |
2051 | @itemx :priority | |
2052 | @itemx :reuseaddr | |
2053 | That particular network option is supported by | |
2054 | @code{make-network-process} and @code{set-network-process-option}. | |
4bb24054 RS |
2055 | @end table |
2056 | ||
ab5796a9 MB |
2057 | @ignore |
2058 | arch-tag: ba9da253-e65f-4e7f-b727-08fba0a1df7a | |
2059 | @end ignore | |
4bb24054 | 2060 |