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
13 ipcs — report XSI interprocess communication facilities status
14
16 ipcs [−qms] [−a|−bcopt]
17
19 The ipcs utility shall write information about active interprocess com‐
20 munication facilities.
21 Without options, information shall be written in short format for mes‐
23 sage queues, shared memory segments, and semaphore sets that are cur‐
24 rently active in the system. Otherwise, the information that is dis‐
25 played is controlled by the options specified.
26
28 The ipcs utility shall conform to the Base Definitions volume of
29 POSIX.1‐2008, Section 12.2, Utility Syntax Guidelines.
30 The ipcs utility accepts the following options:
32 −q Write information about active message queues.
34 −m Write information about active shared memory segments.
36 −s Write information about active semaphore sets.
38 If −q, −m, or −s are specified, only information about those facilities
40 shall be written. If none of these three are specified, information
41 about all three shall be written subject to the following options:
42 −a Use all print options. (This is a shorthand notation for −b,
44 −c, −o, −p, and −t.)
45 −b Write information on maximum allowable size. (Maximum number
47 of bytes in messages on queue for message queues, size of
48 segments for shared memory, and number of semaphores in each
49 set for semaphores.)
50 −c Write creator's user name and group name; see below.
52 −o Write information on outstanding usage. (Number of messages
54 on queue and total number of bytes in messages on queue for
55 message queues, and number of processes attached to shared
56 memory segments.)
57 −p Write process number information. (Process ID of the last
59 process to send a message and process ID of the last process
60 to receive a message on message queues, process ID of the
61 creating process, and process ID of the last process to
62 attach or detach on shared memory segments.)
63 −t Write time information. (Time of the last control operation
65 that changed the access permissions for all facilities, time
66 of the last msgsnd() and msgrcv() operations on message
67 queues, time of the last shmat() and shmdt() operations on
68 shared memory, and time of the last semop() operation on sem‐
69 aphores.)
70
72 None.
73
75 Not used.
76
78 * The group database
79 * The user database
81
83 The following environment variables shall affect the execution of ipcs:
84 LANG Provide a default value for the internationalization vari‐
86 ables that are unset or null. (See the Base Definitions vol‐
87 ume of POSIX.1‐2008, Section 8.2, Internationalization Vari‐
88 ables for the precedence of internationalization variables
89 used to determine the values of locale categories.)
90 LC_ALL If set to a non-empty string value, override the values of
92 all the other internationalization variables.
93 LC_CTYPE Determine the locale for the interpretation of sequences of
95 bytes of text data as characters (for example, single-byte as
96 opposed to multi-byte characters in arguments).
97 LC_MESSAGES
99 Determine the locale that should be used to affect the format
100 and contents of diagnostic messages written to standard
101 error.
102 NLSPATH Determine the location of message catalogs for the processing
104 of LC_MESSAGES.
105 TZ Determine the timezone for the date and time strings written
107 by ipcs. If TZ is unset or null, an unspecified default
108 timezone shall be used.
109
111 Default.
112
114 An introductory line shall be written with the format:
115 "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>
133 where <facility> is Message Queue, Shared Memory, or Semaphore, as
135 appropriate. If the facility has been installed and has been used since
136 the last reboot, column headings separated by one or more <space> char‐
137 acters and followed by a <newline> shall be written as indicated below
138 followed by the facility name written out using the format:
139 "%s:\n", <facility>
141 where <facility> is Message Queues, Shared Memory, or Semaphores, as
143 appropriate. On the second and third reports the column headings need
144 not be written if the last column headings written already provide col‐
145 umn headings for all information in that report.
146 The column headings provided in the first column below and the meaning
148 of the information in those columns shall be given in order below; the
149 letters in parentheses indicate the options that shall cause the corre‐
150 sponding column to appear; ``all'' means that the column shall always
151 appear. Each column is separated by one or more <space> characters.
152 Note that these options only determine what information is provided for
153 each report; they do not determine which reports are written.
154 T (all) Type of facility:
156 q Message queue.
158 m Shared memory segment.
160 s Semaphore.
162 This field is a single character written using the format
164 %c.
165 ID (all) The identifier for the facility entry. This field shall be
167 written using the format %d.
168 KEY (all) The key used as an argument to msgget(), semget(), or
170 shmget() to create the facility entry.
171 Note: The key of a shared memory segment is changed to
173 IPC_PRIVATE when the segment has been removed
174 until all processes attached to the segment
175 detach it.
176 This field shall be written using the format 0x%x.
178 MODE (all) The facility access modes and flags. The mode shall consist
180 of 11 characters that are interpreted as follows.
181 The first character shall be:
183 S If a process is waiting on a msgsnd() operation.
185 − If the above is not true.
187 The second character shall be:
189 R If a process is waiting on a msgrcv() operation.
191 C or − If the associated shared memory segment is to be
193 cleared when the first attach operation is exe‐
194 cuted.
195 − If none of the above is true.
197 The next nine characters shall be interpreted as three sets
199 of three bits each. The first set refers to the owner's
200 permissions; the next to permissions of others in the user‐
201 group of the facility entry; and the last to all others.
202 Within each set, the first character indicates permission
203 to read, the second character indicates permission to write
204 or alter the facility entry, and the last character is a
205 minus-sign ('−').
206 The permissions shall be indicated as follows:
208 r If read permission is granted.
210 w If write permission is granted.
212 a If alter permission is granted.
214 − If the indicated permission is not granted.
216 The first character following the permissions specifies if
218 there is an alternate or additional access control method
219 associated with the facility. If there is no alternate or
220 additional access control method associated with the facil‐
221 ity, a single <space> shall be written; otherwise, another
222 printable character is written.
223 OWNER (all) The user name of the owner of the facility entry. If the
225 user name of the owner is found in the user database, at
226 least the first eight column positions of the name shall be
227 written using the format %s. Otherwise, the user ID of the
228 owner shall be written using the format %d.
229 GROUP (all) The group name of the owner of the facility entry. If the
231 group name of the owner is found in the group database, at
232 least the first eight column positions of the name shall be
233 written using the format %s. Otherwise, the group ID of
234 the owner shall be written using the format %d.
235 The following nine columns shall be only written out for message
237 queues:
238 CREATOR (a,c)
240 The user name of the creator of the facility entry. If the
241 user name of the creator is found in the user database, at
242 least the first eight column positions of the name shall be
243 written using the format %s. Otherwise, the user ID of the
244 creator shall be written using the format %d.
245 CGROUP (a,c)
247 The group name of the creator of the facility entry. If the
248 group name of the creator is found in the group database,
249 at least the first eight column positions of the name shall
250 be written using the format %s. Otherwise, the group ID of
251 the creator shall be written using the format %d.
252 CBYTES (a,o)
254 The number of bytes in messages currently outstanding on
255 the associated message queue. This field shall be written
256 using the format %d.
257 QNUM (a,o) The number of messages currently outstanding on the associ‐
259 ated message queue. This field shall be written using the
260 format %d.
261 QBYTES (a,b)
263 The maximum number of bytes allowed in messages outstanding
264 on the associated message queue. This field shall be writ‐
265 ten using the format %d.
266 LSPID (a,p) The process ID of the last process to send a message to the
268 associated queue. This field shall be written using the
269 format:
270 "%d", <pid>
272 where <pid> is 0 if no message has been sent to the corre‐
274 sponding message queue; otherwise, <pid> shall be the
275 process ID of the last process to send a message to the
276 queue.
277 LRPID (a,p) The process ID of the last process to receive a message
279 from the associated queue. This field shall be written
280 using the format:
281 "%d", <pid>
283 where <pid> is 0 if no message has been received from the
285 corresponding message queue; otherwise, <pid> shall be the
286 process ID of the last process to receive a message from
287 the queue.
288 STIME (a,t) The time the last message was sent to the associated queue.
290 If a message has been sent to the corresponding message
291 queue, the hour, minute, and second of the last time a mes‐
292 sage was sent to the queue shall be written using the for‐
293 mat %d:%2.2d:%2.2d. Otherwise, the format " no-entry"
294 shall be written.
295 RTIME (a,t) The time the last message was received from the associated
297 queue. If a message has been received from the correspond‐
298 ing message queue, the hour, minute, and second of the last
299 time a message was received from the queue shall be written
300 using the format %d:%2.2d:%2.2d. Otherwise, the format
301 " no-entry" shall be written.
302 The following eight columns shall be only written out for shared memory
304 segments.
305 CREATOR (a,c)
307 The user of the creator of the facility entry. If the user
308 name of the creator is found in the user database, at least
309 the first eight column positions of the name shall be writ‐
310 ten using the format %s. Otherwise, the user ID of the
311 creator shall be written using the format %d.
312 CGROUP (a,c)
314 The group name of the creator of the facility entry. If the
315 group name of the creator is found in the group database,
316 at least the first eight column positions of the name shall
317 be written using the format %s. Otherwise, the group ID of
318 the creator shall be written using the format %d.
319 NATTCH (a,o)
321 The number of processes attached to the associated shared
322 memory segment. This field shall be written using the for‐
323 mat %d.
324 SEGSZ (a,b) The size of the associated shared memory segment. This
326 field shall be written using the format %d.
327 CPID (a,p) The process ID of the creator of the shared memory entry.
329 This field shall be written using the format %d.
330 LPID (a,p) The process ID of the last process to attach or detach the
332 shared memory segment. This field shall be written using
333 the format:
334 "%d", <pid>
336 where <pid> is 0 if no process has attached the correspond‐
338 ing shared memory segment; otherwise, <pid> shall be the
339 process ID of the last process to attach or detach the seg‐
340 ment.
341 ATIME (a,t) The time the last attach on the associated shared memory
343 segment was completed. If the corresponding shared memory
344 segment has ever been attached, the hour, minute, and sec‐
345 ond of the last time the segment was attached shall be
346 written using the format %d:%2.2d:%2.2d. Otherwise, the
347 format " no-entry" shall be written.
348 DTIME (a,t) The time the last detach on the associated shared memory
350 segment was completed. If the corresponding shared memory
351 segment has ever been detached, the hour, minute, and sec‐
352 ond of the last time the segment was detached shall be
353 written using the format %d:%2.2d:%2.2d. Otherwise, the
354 format " no-entry" shall be written.
355 The following four columns shall be only written out for semaphore
357 sets:
358 CREATOR (a,c)
360 The user of the creator of the facility entry. If the user
361 name of the creator is found in the user database, at least
362 the first eight column positions of the name shall be writ‐
363 ten using the format %s. Otherwise, the user ID of the
364 creator shall be written using the format %d.
365 CGROUP (a,c)
367 The group name of the creator of the facility entry. If the
368 group name of the creator is found in the group database,
369 at least the first eight column positions of the name shall
370 be written using the format %s. Otherwise, the group ID of
371 the creator shall be written using the format %d.
372 NSEMS (a,b) The number of semaphores in the set associated with the
374 semaphore entry. This field shall be written using the for‐
375 mat %d.
376 OTIME (a,t) The time the last semaphore operation on the set associated
378 with the semaphore entry was completed. If a semaphore
379 operation has ever been performed on the corresponding sem‐
380 aphore set, the hour, minute, and second of the last sema‐
381 phore operation on the semaphore set shall be written using
382 the format %d:%2.2d:%2.2d. Otherwise, the format " no-
383 entry" shall be written.
384 The following column shall be written for all three reports when it is
386 requested:
387 CTIME (a,t) The time the associated entry was created or changed. The
389 hour, minute, and second of the time when the associated
390 entry was created shall be written using the format
391 %d:%2.2d:%2.2d.
392
394 The standard error shall be used only for diagnostic messages.
395
397 None.
398
400 None.
401
403 The following exit values shall be returned:
404 0 Successful completion.
406 >0 An error occurred.
408
410 Default.
411 The following sections are informative.
413
415 Things can change while ipcs is running; the information it gives is
416 guaranteed to be accurate only when it was retrieved.
417
419 None.
420
422 None.
423
425 None.
426
428 ipcrm
429 The Base Definitions volume of POSIX.1‐2008, Chapter 8, Environment
431 Variables, Section 12.2, Utility Syntax Guidelines
432 The System Interfaces volume of POSIX.1‐2008, msgrcv(), msgsnd(),
434 semget(), semop(), shmat(), shmdt(), shmget()
435
437 Portions of this text are reprinted and reproduced in electronic form
438 from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
439 -- Portable Operating System Interface (POSIX), The Open Group Base
440 Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
441 cal and Electronics Engineers, Inc and The Open Group. (This is
442 POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
443 event of any discrepancy between this version and the original IEEE and
444 The Open Group Standard, the original IEEE and The Open Group Standard
445 is the referee document. The original Standard can be obtained online
446 at http://www.unix.org/online.html .
447 Any typographical or formatting errors that appear in this page are
449 most likely to have been introduced during the conversion of the source
450 files to man page format. To report such errors, see https://www.ker‐
451 nel.org/doc/man-pages/reporting_bugs.html .
452IEEE/The Open Group 2013 IPCS(1P)