1IPCS(1P) POSIX Programmer's Manual IPCS(1P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
12 ipcs — report XSI interprocess communication facilities status
13
15 ipcs [-qms] [-a|-bcopt]
16
18 The ipcs utility shall write information about active interprocess com‐
19 munication facilities.
20 Without options, information shall be written in short format for mes‐
22 sage queues, shared memory segments, and semaphore sets that are cur‐
23 rently active in the system. Otherwise, the information that is dis‐
24 played is controlled by the options specified.
25
27 The ipcs utility shall conform to the Base Definitions volume of
28 POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines.
29 The ipcs utility accepts the following options:
31 -q Write information about active message queues.
33 -m Write information about active shared memory segments.
35 -s Write information about active semaphore sets.
37 If -q, -m, or -s are specified, only information about those facilities
39 shall be written. If none of these three are specified, information
40 about all three shall be written subject to the following options:
41 -a Use all print options. (This is a shorthand notation for -b,
43 -c, -o, -p, and -t.)
44 -b Write information on maximum allowable size. (Maximum number
46 of bytes in messages on queue for message queues, size of
47 segments for shared memory, and number of semaphores in each
48 set for semaphores.)
49 -c Write creator's user name and group name; see below.
51 -o Write information on outstanding usage. (Number of messages
53 on queue and total number of bytes in messages on queue for
54 message queues, and number of processes attached to shared
55 memory segments.)
56 -p Write process number information. (Process ID of the last
58 process to send a message and process ID of the last process
59 to receive a message on message queues, process ID of the
60 creating process, and process ID of the last process to
61 attach or detach on shared memory segments.)
62 -t Write time information. (Time of the last control operation
64 that changed the access permissions for all facilities, time
65 of the last msgsnd() and msgrcv() operations on message
66 queues, time of the last shmat() and shmdt() operations on
67 shared memory, and time of the last semop() operation on sem‐
68 aphores.)
69
71 None.
72
74 Not used.
75
77 * The group database
78 * The user database
80
82 The following environment variables shall affect the execution of ipcs:
83 LANG Provide a default value for the internationalization vari‐
85 ables that are unset or null. (See the Base Definitions vol‐
86 ume of POSIX.1‐2017, Section 8.2, Internationalization Vari‐
87 ables for the precedence of internationalization variables
88 used to determine the values of locale categories.)
89 LC_ALL If set to a non-empty string value, override the values of
91 all the other internationalization variables.
92 LC_CTYPE Determine the locale for the interpretation of sequences of
94 bytes of text data as characters (for example, single-byte as
95 opposed to multi-byte characters in arguments).
96 LC_MESSAGES
98 Determine the locale that should be used to affect the format
99 and contents of diagnostic messages written to standard
100 error.
101 NLSPATH Determine the location of message catalogs for the processing
103 of LC_MESSAGES.
104 TZ Determine the timezone for the date and time strings written
106 by ipcs. If TZ is unset or null, an unspecified default
107 timezone shall be used.
108
110 Default.
111
113 An introductory line shall be written with the format:
114 "IPC status from %s as of %s\n", <source>, <date>
117 where <source> indicates the source used to gather the statistics and
119 <date> is the information that would be produced by the date command
120 when invoked in the POSIX locale.
121 The ipcs utility then shall create up to three reports depending upon
123 the -q, -m, and -s options. The first report shall indicate the status
124 of message queues, the second report shall indicate the status of
125 shared memory segments, and the third report shall indicate the status
126 of semaphore sets.
127 If the corresponding facility is not installed or has not been used
129 since the last reboot, then the report shall be written out in the for‐
130 mat:
131 "%s facility not in system.\n", <facility>
134 where <facility> is Message Queue, Shared Memory, or Semaphore, as
136 appropriate. If the facility has been installed and has been used since
137 the last reboot, column headings separated by one or more <space> char‐
138 acters and followed by a <newline> shall be written as indicated below
139 followed by the facility name written out using the format:
140 "%s:\n", <facility>
143 where <facility> is Message Queues, Shared Memory, or Semaphores, as
145 appropriate. On the second and third reports the column headings need
146 not be written if the last column headings written already provide col‐
147 umn headings for all information in that report.
148 The column headings provided in the first column below and the meaning
150 of the information in those columns shall be given in order below; the
151 letters in parentheses indicate the options that shall cause the corre‐
152 sponding column to appear; ``all'' means that the column shall always
153 appear. Each column is separated by one or more <space> characters.
154 Note that these options only determine what information is provided for
155 each report; they do not determine which reports are written.
156 T (all) Type of facility:
158 q Message queue.
160 m Shared memory segment.
162 s Semaphore.
164 This field is a single character written using the format
166 %c.
167 ID (all) The identifier for the facility entry. This field shall be
169 written using the format %d.
170 KEY (all) The key used as an argument to msgget(), semget(), or
172 shmget() to create the facility entry.
173 Note: The key of a shared memory segment is changed to
175 IPC_PRIVATE when the segment has been removed
176 until all processes attached to the segment
177 detach it.
178 This field shall be written using the format 0x%x.
180 MODE (all) The facility access modes and flags. The mode shall consist
182 of 11 characters that are interpreted as follows.
183 The first character shall be:
185 S If a process is waiting on a msgsnd() operation.
187 - If the above is not true.
189 The second character shall be:
191 R If a process is waiting on a msgrcv() operation.
193 C or - If the associated shared memory segment is to be
195 cleared when the first attach operation is exe‐
196 cuted.
197 - If none of the above is true.
199 The next nine characters shall be interpreted as three sets
201 of three bits each. The first set refers to the owner's
202 permissions; the next to permissions of others in the user‐
203 group of the facility entry; and the last to all others.
204 Within each set, the first character indicates permission
205 to read, the second character indicates permission to write
206 or alter the facility entry, and the last character is a
207 <hyphen-minus> ('-').
208 The permissions shall be indicated as follows:
210 r If read permission is granted.
212 w If write permission is granted.
214 a If alter permission is granted.
216 - If the indicated permission is not granted.
218 The first character following the permissions specifies if
220 there is an alternate or additional access control method
221 associated with the facility. If there is no alternate or
222 additional access control method associated with the facil‐
223 ity, a single <space> shall be written; otherwise, another
224 printable character is written.
225 OWNER (all) The user name of the owner of the facility entry. If the
227 user name of the owner is found in the user database, at
228 least the first eight column positions of the name shall be
229 written using the format %s. Otherwise, the user ID of the
230 owner shall be written using the format %d.
231 GROUP (all) The group name of the owner of the facility entry. If the
233 group name of the owner is found in the group database, at
234 least the first eight column positions of the name shall be
235 written using the format %s. Otherwise, the group ID of
236 the owner shall be written using the format %d.
237 The following nine columns shall be only written out for message
239 queues:
240 CREATOR (a,c)
242 The user name of the creator of the facility entry. If the
243 user name of the creator is found in the user database, at
244 least the first eight column positions of the name shall be
245 written using the format %s. Otherwise, the user ID of the
246 creator shall be written using the format %d.
247 CGROUP (a,c)
249 The group name of the creator of the facility entry. If the
250 group name of the creator is found in the group database,
251 at least the first eight column positions of the name shall
252 be written using the format %s. Otherwise, the group ID of
253 the creator shall be written using the format %d.
254 CBYTES (a,o)
256 The number of bytes in messages currently outstanding on
257 the associated message queue. This field shall be written
258 using the format %d.
259 QNUM (a,o) The number of messages currently outstanding on the associ‐
261 ated message queue. This field shall be written using the
262 format %d.
263 QBYTES (a,b)
265 The maximum number of bytes allowed in messages outstanding
266 on the associated message queue. This field shall be writ‐
267 ten using the format %d.
268 LSPID (a,p) The process ID of the last process to send a message to the
270 associated queue. This field shall be written using the
271 format:
272 "%d", <pid>
275 where <pid> is 0 if no message has been sent to the corre‐
277 sponding message queue; otherwise, <pid> shall be the
278 process ID of the last process to send a message to the
279 queue.
280 LRPID (a,p) The process ID of the last process to receive a message
282 from the associated queue. This field shall be written
283 using the format:
284 "%d", <pid>
287 where <pid> is 0 if no message has been received from the
289 corresponding message queue; otherwise, <pid> shall be the
290 process ID of the last process to receive a message from
291 the queue.
292 STIME (a,t) The time the last message was sent to the associated queue.
294 If a message has been sent to the corresponding message
295 queue, the hour, minute, and second of the last time a mes‐
296 sage was sent to the queue shall be written using the for‐
297 mat %d:%2.2d:%2.2d. Otherwise, the format " no-entry"
298 shall be written.
299 RTIME (a,t) The time the last message was received from the associated
301 queue. If a message has been received from the correspond‐
302 ing message queue, the hour, minute, and second of the last
303 time a message was received from the queue shall be written
304 using the format %d:%2.2d:%2.2d. Otherwise, the format
305 " no-entry" shall be written.
306 The following eight columns shall be only written out for shared memory
308 segments.
309 CREATOR (a,c)
311 The user of the creator of the facility entry. If the user
312 name of the creator is found in the user database, at least
313 the first eight column positions of the name shall be writ‐
314 ten using the format %s. Otherwise, the user ID of the
315 creator shall be written using the format %d.
316 CGROUP (a,c)
318 The group name of the creator of the facility entry. If the
319 group name of the creator is found in the group database,
320 at least the first eight column positions of the name shall
321 be written using the format %s. Otherwise, the group ID of
322 the creator shall be written using the format %d.
323 NATTCH (a,o)
325 The number of processes attached to the associated shared
326 memory segment. This field shall be written using the for‐
327 mat %d.
328 SEGSZ (a,b) The size of the associated shared memory segment. This
330 field shall be written using the format %d.
331 CPID (a,p) The process ID of the creator of the shared memory entry.
333 This field shall be written using the format %d.
334 LPID (a,p) The process ID of the last process to attach or detach the
336 shared memory segment. This field shall be written using
337 the format:
338 "%d", <pid>
341 where <pid> is 0 if no process has attached the correspond‐
343 ing shared memory segment; otherwise, <pid> shall be the
344 process ID of the last process to attach or detach the seg‐
345 ment.
346 ATIME (a,t) The time the last attach on the associated shared memory
348 segment was completed. If the corresponding shared memory
349 segment has ever been attached, the hour, minute, and sec‐
350 ond of the last time the segment was attached shall be
351 written using the format %d:%2.2d:%2.2d. Otherwise, the
352 format " no-entry" shall be written.
353 DTIME (a,t) The time the last detach on the associated shared memory
355 segment was completed. If the corresponding shared memory
356 segment has ever been detached, the hour, minute, and sec‐
357 ond of the last time the segment was detached shall be
358 written using the format %d:%2.2d:%2.2d. Otherwise, the
359 format " no-entry" shall be written.
360 The following four columns shall be only written out for semaphore
362 sets:
363 CREATOR (a,c)
365 The user of the creator of the facility entry. If the user
366 name of the creator is found in the user database, at least
367 the first eight column positions of the name shall be writ‐
368 ten using the format %s. Otherwise, the user ID of the
369 creator shall be written using the format %d.
370 CGROUP (a,c)
372 The group name of the creator of the facility entry. If the
373 group name of the creator is found in the group database,
374 at least the first eight column positions of the name shall
375 be written using the format %s. Otherwise, the group ID of
376 the creator shall be written using the format %d.
377 NSEMS (a,b) The number of semaphores in the set associated with the
379 semaphore entry. This field shall be written using the for‐
380 mat %d.
381 OTIME (a,t) The time the last semaphore operation on the set associated
383 with the semaphore entry was completed. If a semaphore
384 operation has ever been performed on the corresponding sem‐
385 aphore set, the hour, minute, and second of the last sema‐
386 phore operation on the semaphore set shall be written using
387 the format %d:%2.2d:%2.2d. Otherwise, the format " no-
388 entry" shall be written.
389 The following column shall be written for all three reports when it is
391 requested:
392 CTIME (a,t) The time the associated entry was created or changed. The
394 hour, minute, and second of the time when the associated
395 entry was created shall be written using the format
396 %d:%2.2d:%2.2d.
397
399 The standard error shall be used only for diagnostic messages.
400
402 None.
403
405 None.
406
408 The following exit values shall be returned:
409 0 Successful completion.
411 >0 An error occurred.
413
415 Default.
416 The following sections are informative.
418
420 Things can change while ipcs is running; the information it gives is
421 guaranteed to be accurate only when it was retrieved.
422
424 None.
425
427 None.
428
430 None.
431
433 ipcrm
434 The Base Definitions volume of POSIX.1‐2017, Chapter 8, Environment
436 Variables, Section 12.2, Utility Syntax Guidelines
437 The System Interfaces volume of POSIX.1‐2017, msgrcv(), msgsnd(),
439 semget(), semop(), shmat(), shmdt(), shmget()
440
442 Portions of this text are reprinted and reproduced in electronic form
443 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
444 table Operating System Interface (POSIX), The Open Group Base Specifi‐
445 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
446 Electrical and Electronics Engineers, Inc and The Open Group. In the
447 event of any discrepancy between this version and the original IEEE and
448 The Open Group Standard, the original IEEE and The Open Group Standard
449 is the referee document. The original Standard can be obtained online
450 at http://www.opengroup.org/unix/online.html .
451 Any typographical or formatting errors that appear in this page are
453 most likely to have been introduced during the conversion of the source
454 files to man page format. To report such errors, see https://www.ker‐
455 nel.org/doc/man-pages/reporting_bugs.html .
456IEEE/The Open Group 2017 IPCS(1P)