1posixoptions(7) Miscellaneous Information Manual posixoptions(7)
2
6 posixoptions - optional parts of the POSIX standard
7
9 The POSIX standard (the information below is from POSIX.1-2001) de‐
10 scribes a set of behaviors and interfaces for a compliant system. How‐
11 ever, many interfaces are optional and there are feature test macros to
12 test the availability of interfaces at compile time, and functions
13 sysconf(3), fpathconf(3), pathconf(3), confstr(3) to do this at run
14 time. From shell scripts one can use getconf(1). For more detail, see
15 sysconf(3).
16 We give the name of the POSIX abbreviation, the option, the name of the
18 sysconf(3) parameter used to inquire about the option, and possibly a
19 very short description. Much more precise detail can be found in the
20 POSIX standard itself, versions of which can nowadays be accessed
21 freely on the web.
22 ADV - _POSIX_ADVISORY_INFO - _SC_ADVISORY_INFO
24 The following advisory functions are present:
25 posix_fadvise()
27 posix_fallocate()
28 posix_memalign()
29 posix_madvise()
30 AIO - _POSIX_ASYNCHRONOUS_IO - _SC_ASYNCHRONOUS_IO
32 The header <aio.h> is present. The following functions are present:
33 aio_cancel()
35 aio_error()
36 aio_fsync()
37 aio_read()
38 aio_return()
39 aio_suspend()
40 aio_write()
41 lio_listio()
42 BAR - _POSIX_BARRIERS - _SC_BARRIERS
44 This option implies the _POSIX_THREADS and _POSIX_THREAD_SAFE_FUNCTIONS
45 options. The following functions are present:
46 pthread_barrier_destroy()
48 pthread_barrier_init()
49 pthread_barrier_wait()
50 pthread_barrierattr_destroy()
51 pthread_barrierattr_init()
52 --- - POSIX_CHOWN_RESTRICTED
54 If this option is in effect (as it always is under POSIX.1-2001), then
55 only root may change the owner of a file, and nonroot can set the group
56 of a file only to one of the groups it belongs to. This affects the
57 following functions
58 chown()
60 fchown()
61 CS - _POSIX_CLOCK_SELECTION - _SC_CLOCK_SELECTION
63 This option implies the _POSIX_TIMERS option. The following functions
64 are present:
65 pthread_condattr_getclock()
67 pthread_condattr_setclock()
68 clock_nanosleep()
69 If CLOCK_REALTIME is changed by the function clock_settime(), then this
71 affects all timers set for an absolute time.
72 CPT - _POSIX_CPUTIME - _SC_CPUTIME
74 The CLOCK_PROCESS_CPUTIME_ID clock ID is supported. The initial value
75 of this clock is 0 for each process. This option implies the
76 _POSIX_TIMERS option. The function clock_getcpuclockid() is present.
77 --- - _POSIX_FILE_LOCKING - _SC_FILE_LOCKING
79 This option has been deleted. Not in final XPG6.
80 FSC - _POSIX_FSYNC - _SC_FSYNC
82 The function fsync() is present.
83 IP6 - _POSIX_IPV6 - _SC_IPV6
85 Internet Protocol Version 6 is supported.
86 --- - _POSIX_JOB_CONTROL - _SC_JOB_CONTROL
88 If this option is in effect (as it always is under POSIX.1-2001), then
89 the system implements POSIX-style job control, and the following func‐
90 tions are present:
91 setpgid()
93 tcdrain()
94 tcflush()
95 tcgetpgrp()
96 tcsendbreak()
97 tcsetattr()
98 tcsetpgrp()
99 MF - _POSIX_MAPPED_FILES - _SC_MAPPED_FILES
101 Shared memory is supported. The include file <sys/mman.h> is present.
102 The following functions are present:
103 mmap()
105 msync()
106 munmap()
107 ML - _POSIX_MEMLOCK - _SC_MEMLOCK
109 Shared memory can be locked into core. The following functions are
110 present:
111 mlockall()
113 munlockall()
114 MR/MLR - _POSIX_MEMLOCK_RANGE - _SC_MEMLOCK_RANGE
116 More precisely, ranges can be locked into core. The following func‐
117 tions are present:
118 mlock()
120 munlock()
121 MPR - _POSIX_MEMORY_PROTECTION - _SC_MEMORY_PROTECTION
123 The function mprotect() is present.
124 MSG - _POSIX_MESSAGE_PASSING - _SC_MESSAGE_PASSING
126 The include file <mqueue.h> is present. The following functions are
127 present:
128 mq_close()
130 mq_getattr()
131 mq_notify()
132 mq_open()
133 mq_receive()
134 mq_send()
135 mq_setattr()
136 mq_unlink()
137 MON - _POSIX_MONOTONIC_CLOCK - _SC_MONOTONIC_CLOCK
139 CLOCK_MONOTONIC is supported. This option implies the _POSIX_TIMERS
140 option. The following functions are affected:
141 aio_suspend()
143 clock_getres()
144 clock_gettime()
145 clock_settime()
146 timer_create()
147 --- - _POSIX_MULTI_PROCESS - _SC_MULTI_PROCESS
149 This option has been deleted. Not in final XPG6.
150 --- - _POSIX_NO_TRUNC
152 If this option is in effect (as it always is under POSIX.1-2001), then
153 pathname components longer than NAME_MAX are not truncated, but give an
154 error. This property may be dependent on the path prefix of the compo‐
155 nent.
156 PIO - _POSIX_PRIORITIZED_IO - _SC_PRIORITIZED_IO
158 This option says that one can specify priorities for asynchronous I/O.
159 This affects the functions
160 aio_read()
162 aio_write()
163 PS - _POSIX_PRIORITY_SCHEDULING - _SC_PRIORITY_SCHEDULING
165 The include file <sched.h> is present. The following functions are
166 present:
167 sched_get_priority_max()
169 sched_get_priority_min()
170 sched_getparam()
171 sched_getscheduler()
172 sched_rr_get_interval()
173 sched_setparam()
174 sched_setscheduler()
175 sched_yield()
176 If also _POSIX_SPAWN is in effect, then the following functions are
178 present:
179 posix_spawnattr_getschedparam()
181 posix_spawnattr_getschedpolicy()
182 posix_spawnattr_setschedparam()
183 posix_spawnattr_setschedpolicy()
184 RS - _POSIX_RAW_SOCKETS
186 Raw sockets are supported. The following functions are affected:
187 getsockopt()
189 setsockopt()
190 --- - _POSIX_READER_WRITER_LOCKS - _SC_READER_WRITER_LOCKS
192 This option implies the _POSIX_THREADS option. Conversely, under
193 POSIX.1-2001 the _POSIX_THREADS option implies this option.
194 The following functions are present:
196 pthread_rwlock_destroy()
198 pthread_rwlock_init()
199 pthread_rwlock_rdlock()
200 pthread_rwlock_tryrdlock()
201 pthread_rwlock_trywrlock()
202 pthread_rwlock_unlock()
203 pthread_rwlock_wrlock()
204 pthread_rwlockattr_destroy()
205 pthread_rwlockattr_init()
206 RTS - _POSIX_REALTIME_SIGNALS - _SC_REALTIME_SIGNALS
208 Realtime signals are supported. The following functions are present:
209 sigqueue()
211 sigtimedwait()
212 sigwaitinfo()
213 --- - _POSIX_REGEXP - _SC_REGEXP
215 If this option is in effect (as it always is under POSIX.1-2001), then
216 POSIX regular expressions are supported and the following functions are
217 present:
218 regcomp()
220 regerror()
221 regexec()
222 regfree()
223 --- - _POSIX_SAVED_IDS - _SC_SAVED_IDS
225 If this option is in effect (as it always is under POSIX.1-2001), then
226 a process has a saved set-user-ID and a saved set-group-ID. The fol‐
227 lowing functions are affected:
228 exec()
230 kill()
231 seteuid()
232 setegid()
233 setgid()
234 setuid()
235 SEM - _POSIX_SEMAPHORES - _SC_SEMAPHORES
237 The include file <semaphore.h> is present. The following functions are
238 present:
239 sem_close()
241 sem_destroy()
242 sem_getvalue()
243 sem_init()
244 sem_open()
245 sem_post()
246 sem_trywait()
247 sem_unlink()
248 sem_wait()
249 SHM - _POSIX_SHARED_MEMORY_OBJECTS - _SC_SHARED_MEMORY_OBJECTS
251 The following functions are present:
252 mmap()
254 munmap()
255 shm_open()
256 shm_unlink()
257 --- - _POSIX_SHELL - _SC_SHELL
259 If this option is in effect (as it always is under POSIX.1-2001), the
260 function system() is present.
261 SPN - _POSIX_SPAWN - _SC_SPAWN
263 This option describes support for process creation in a context where
264 it is difficult or impossible to use fork(), for example, because no
265 MMU is present.
266 If _POSIX_SPAWN is in effect, then the include file <spawn.h> and the
268 following functions are present:
269 posix_spawn()
271 posix_spawn_file_actions_addclose()
272 posix_spawn_file_actions_adddup2()
273 posix_spawn_file_actions_addopen()
274 posix_spawn_file_actions_destroy()
275 posix_spawn_file_actions_init()
276 posix_spawnattr_destroy()
277 posix_spawnattr_getsigdefault()
278 posix_spawnattr_getflags()
279 posix_spawnattr_getpgroup()
280 posix_spawnattr_getsigmask()
281 posix_spawnattr_init()
282 posix_spawnattr_setsigdefault()
283 posix_spawnattr_setflags()
284 posix_spawnattr_setpgroup()
285 posix_spawnattr_setsigmask()
286 posix_spawnp()
287 If also _POSIX_PRIORITY_SCHEDULING is in effect, then the following
289 functions are present:
290 posix_spawnattr_getschedparam()
292 posix_spawnattr_getschedpolicy()
293 posix_spawnattr_setschedparam()
294 posix_spawnattr_setschedpolicy()
295 SPI - _POSIX_SPIN_LOCKS - _SC_SPIN_LOCKS
297 This option implies the _POSIX_THREADS and _POSIX_THREAD_SAFE_FUNCTIONS
298 options. The following functions are present:
299 pthread_spin_destroy()
301 pthread_spin_init()
302 pthread_spin_lock()
303 pthread_spin_trylock()
304 pthread_spin_unlock()
305 SS - _POSIX_SPORADIC_SERVER - _SC_SPORADIC_SERVER
307 The scheduling policy SCHED_SPORADIC is supported. This option implies
308 the _POSIX_PRIORITY_SCHEDULING option. The following functions are af‐
309 fected:
310 sched_setparam()
312 sched_setscheduler()
313 SIO - _POSIX_SYNCHRONIZED_IO - _SC_SYNCHRONIZED_IO
315 The following functions are affected:
316 open()
318 msync()
319 fsync()
320 fdatasync()
321 TSA - _POSIX_THREAD_ATTR_STACKADDR - _SC_THREAD_ATTR_STACKADDR
323 The following functions are affected:
324 pthread_attr_getstack()
326 pthread_attr_getstackaddr()
327 pthread_attr_setstack()
328 pthread_attr_setstackaddr()
329 TSS - _POSIX_THREAD_ATTR_STACKSIZE - _SC_THREAD_ATTR_STACKSIZE
331 The following functions are affected:
332 pthread_attr_getstack()
334 pthread_attr_getstacksize()
335 pthread_attr_setstack()
336 pthread_attr_setstacksize()
337 TCT - _POSIX_THREAD_CPUTIME - _SC_THREAD_CPUTIME
339 The clockID CLOCK_THREAD_CPUTIME_ID is supported. This option implies
340 the _POSIX_TIMERS option. The following functions are affected:
341 pthread_getcpuclockid()
343 clock_getres()
344 clock_gettime()
345 clock_settime()
346 timer_create()
347 TPI - _POSIX_THREAD_PRIO_INHERIT - _SC_THREAD_PRIO_INHERIT
349 The following functions are affected:
350 pthread_mutexattr_getprotocol()
352 pthread_mutexattr_setprotocol()
353 TPP - _POSIX_THREAD_PRIO_PROTECT - _SC_THREAD_PRIO_PROTECT
355 The following functions are affected:
356 pthread_mutex_getprioceiling()
358 pthread_mutex_setprioceiling()
359 pthread_mutexattr_getprioceiling()
360 pthread_mutexattr_getprotocol()
361 pthread_mutexattr_setprioceiling()
362 pthread_mutexattr_setprotocol()
363 TPS - _POSIX_THREAD_PRIORITY_SCHEDULING - _SC_THREAD_PRIORITY_SCHEDULING
365 If this option is in effect, the different threads inside a process can
366 run with different priorities and/or different schedulers. The follow‐
367 ing functions are affected:
368 pthread_attr_getinheritsched()
370 pthread_attr_getschedpolicy()
371 pthread_attr_getscope()
372 pthread_attr_setinheritsched()
373 pthread_attr_setschedpolicy()
374 pthread_attr_setscope()
375 pthread_getschedparam()
376 pthread_setschedparam()
377 pthread_setschedprio()
378 TSH - _POSIX_THREAD_PROCESS_SHARED - _SC_THREAD_PROCESS_SHARED
380 The following functions are affected:
381 pthread_barrierattr_getpshared()
383 pthread_barrierattr_setpshared()
384 pthread_condattr_getpshared()
385 pthread_condattr_setpshared()
386 pthread_mutexattr_getpshared()
387 pthread_mutexattr_setpshared()
388 pthread_rwlockattr_getpshared()
389 pthread_rwlockattr_setpshared()
390 TSF - _POSIX_THREAD_SAFE_FUNCTIONS - _SC_THREAD_SAFE_FUNCTIONS
392 The following functions are affected:
393 readdir_r()
395 getgrgid_r()
396 getgrnam_r()
397 getpwnam_r()
398 getpwuid_r()
399 flockfile()
400 ftrylockfile()
401 funlockfile()
402 getc_unlocked()
403 getchar_unlocked()
404 putc_unlocked()
405 putchar_unlocked()
406 rand_r()
407 strerror_r()
408 strtok_r()
409 asctime_r()
410 ctime_r()
411 gmtime_r()
412 localtime_r()
413 TSP - _POSIX_THREAD_SPORADIC_SERVER - _SC_THREAD_SPORADIC_SERVER
415 This option implies the _POSIX_THREAD_PRIORITY_SCHEDULING option. The
416 following functions are affected:
417 sched_getparam()
419 sched_setparam()
420 sched_setscheduler()
421 THR - _POSIX_THREADS - _SC_THREADS
423 Basic support for POSIX threads is available. The following functions
424 are present:
425 pthread_atfork()
427 pthread_attr_destroy()
428 pthread_attr_getdetachstate()
429 pthread_attr_getschedparam()
430 pthread_attr_init()
431 pthread_attr_setdetachstate()
432 pthread_attr_setschedparam()
433 pthread_cancel()
434 pthread_cleanup_push()
435 pthread_cleanup_pop()
436 pthread_cond_broadcast()
437 pthread_cond_destroy()
438 pthread_cond_init()
439 pthread_cond_signal()
440 pthread_cond_timedwait()
441 pthread_cond_wait()
442 pthread_condattr_destroy()
443 pthread_condattr_init()
444 pthread_create()
445 pthread_detach()
446 pthread_equal()
447 pthread_exit()
448 pthread_getspecific()
449 pthread_join()
450 pthread_key_create()
451 pthread_key_delete()
452 pthread_mutex_destroy()
453 pthread_mutex_init()
454 pthread_mutex_lock()
455 pthread_mutex_trylock()
456 pthread_mutex_unlock()
457 pthread_mutexattr_destroy()
458 pthread_mutexattr_init()
459 pthread_once()
460 pthread_rwlock_destroy()
461 pthread_rwlock_init()
462 pthread_rwlock_rdlock()
463 pthread_rwlock_tryrdlock()
464 pthread_rwlock_trywrlock()
465 pthread_rwlock_unlock()
466 pthread_rwlock_wrlock()
467 pthread_rwlockattr_destroy()
468 pthread_rwlockattr_init()
469 pthread_self()
470 pthread_setcancelstate()
471 pthread_setcanceltype()
472 pthread_setspecific()
473 pthread_testcancel()
474 TMO - _POSIX_TIMEOUTS - _SC_TIMEOUTS
476 The following functions are present:
477 mq_timedreceive()
479 mq_timedsend()
480 pthread_mutex_timedlock()
481 pthread_rwlock_timedrdlock()
482 pthread_rwlock_timedwrlock()
483 sem_timedwait()
484 posix_trace_timedgetnext_event()
485 TMR - _POSIX_TIMERS - _SC_TIMERS
487 The following functions are present:
488 clock_getres()
490 clock_gettime()
491 clock_settime()
492 nanosleep()
493 timer_create()
494 timer_delete()
495 timer_gettime()
496 timer_getoverrun()
497 timer_settime()
498 TRC - _POSIX_TRACE - _SC_TRACE
500 POSIX tracing is available. The following functions are present:
501 posix_trace_attr_destroy()
503 posix_trace_attr_getclockres()
504 posix_trace_attr_getcreatetime()
505 posix_trace_attr_getgenversion()
506 posix_trace_attr_getmaxdatasize()
507 posix_trace_attr_getmaxsystemeventsize()
508 posix_trace_attr_getmaxusereventsize()
509 posix_trace_attr_getname()
510 posix_trace_attr_getstreamfullpolicy()
511 posix_trace_attr_getstreamsize()
512 posix_trace_attr_init()
513 posix_trace_attr_setmaxdatasize()
514 posix_trace_attr_setname()
515 posix_trace_attr_setstreamsize()
516 posix_trace_attr_setstreamfullpolicy()
517 posix_trace_clear()
518 posix_trace_create()
519 posix_trace_event()
520 posix_trace_eventid_equal()
521 posix_trace_eventid_get_name()
522 posix_trace_eventid_open()
523 posix_trace_eventtypelist_getnext_id()
524 posix_trace_eventtypelist_rewind()
525 posix_trace_flush()
526 posix_trace_get_attr()
527 posix_trace_get_status()
528 posix_trace_getnext_event()
529 posix_trace_shutdown()
530 posix_trace_start()
531 posix_trace_stop()
532 posix_trace_trygetnext_event()
533 TEF - _POSIX_TRACE_EVENT_FILTER - _SC_TRACE_EVENT_FILTER
535 This option implies the _POSIX_TRACE option. The following functions
536 are present:
537 posix_trace_eventset_add()
539 posix_trace_eventset_del()
540 posix_trace_eventset_empty()
541 posix_trace_eventset_fill()
542 posix_trace_eventset_ismember()
543 posix_trace_get_filter()
544 posix_trace_set_filter()
545 posix_trace_trid_eventid_open()
546 TRI - _POSIX_TRACE_INHERIT - _SC_TRACE_INHERIT
548 Tracing children of the traced process is supported. This option im‐
549 plies the _POSIX_TRACE option. The following functions are present:
550 posix_trace_attr_getinherited()
552 posix_trace_attr_setinherited()
553 TRL - _POSIX_TRACE_LOG - _SC_TRACE_LOG
555 This option implies the _POSIX_TRACE option. The following functions
556 are present:
557 posix_trace_attr_getlogfullpolicy()
559 posix_trace_attr_getlogsize()
560 posix_trace_attr_setlogfullpolicy()
561 posix_trace_attr_setlogsize()
562 posix_trace_close()
563 posix_trace_create_withlog()
564 posix_trace_open()
565 posix_trace_rewind()
566 TYM - _POSIX_TYPED_MEMORY_OBJECTS - _SC_TYPED_MEMORY_OBJECT
568 The following functions are present:
569 posix_mem_offset()
571 posix_typed_mem_get_info()
572 posix_typed_mem_open()
573 --- - _POSIX_VDISABLE
575 Always present (probably 0). Value to set a changeable special control
576 character to indicate that it is disabled.
577
579 XSI - _XOPEN_CRYPT - _SC_XOPEN_CRYPT
580 The following functions are present:
581 crypt()
583 encrypt()
584 setkey()
585 XSI - _XOPEN_REALTIME - _SC_XOPEN_REALTIME
587 This option implies the following options:
588 _POSIX_ASYNCHRONOUS_IO==200112L
590 _POSIX_FSYNC
591 _POSIX_MAPPED_FILES
592 _POSIX_MEMLOCK==200112L
593 _POSIX_MEMLOCK_RANGE==200112L
594 _POSIX_MEMORY_PROTECTION
595 _POSIX_MESSAGE_PASSING==200112L
596 _POSIX_PRIORITIZED_IO
597 _POSIX_PRIORITY_SCHEDULING==200112L
598 _POSIX_REALTIME_SIGNALS==200112L
599 _POSIX_SEMAPHORES==200112L
600 _POSIX_SHARED_MEMORY_OBJECTS==200112L
601 _POSIX_SYNCHRONIZED_IO==200112L
602 _POSIX_TIMERS==200112L
603 ADV - --- - ---
605 The Advanced Realtime option group implies that the following options
606 are all defined to 200112L:
607 _POSIX_ADVISORY_INFO
609 _POSIX_CLOCK_SELECTION
610 (implies _POSIX_TIMERS)
611 _POSIX_CPUTIME
612 (implies _POSIX_TIMERS)
613 _POSIX_MONOTONIC_CLOCK
614 (implies _POSIX_TIMERS)
615 _POSIX_SPAWN
616 _POSIX_SPORADIC_SERVER
617 (implies _POSIX_PRIORITY_SCHEDULING)
618 _POSIX_TIMEOUTS
619 _POSIX_TYPED_MEMORY_OBJECTS
620 XSI - _XOPEN_REALTIME_THREADS - _SC_XOPEN_REALTIME_THREADS
622 This option implies that the following options are all defined to
623 200112L:
624 _POSIX_THREAD_PRIO_INHERIT
626 _POSIX_THREAD_PRIO_PROTECT
627 _POSIX_THREAD_PRIORITY_SCHEDULING
628 ADVANCED REALTIME THREADS - --- - ---
630 This option implies that the following options are all defined to
631 200112L:
632 _POSIX_BARRIERS
634 (implies _POSIX_THREADS, _POSIX_THREAD_SAFE_FUNCTIONS)
635 _POSIX_SPIN_LOCKS
636 (implies _POSIX_THREADS, _POSIX_THREAD_SAFE_FUNCTIONS)
637 _POSIX_THREAD_CPUTIME
638 (implies _POSIX_TIMERS)
639 _POSIX_THREAD_SPORADIC_SERVER
640 (implies _POSIX_THREAD_PRIORITY_SCHEDULING)
641 TRACING - --- - ---
643 This option implies that the following options are all defined to
644 200112L:
645 _POSIX_TRACE
647 _POSIX_TRACE_EVENT_FILTER
648 _POSIX_TRACE_LOG
649 _POSIX_TRACE_INHERIT
650 STREAMS - _XOPEN_STREAMS - _SC_XOPEN_STREAMS
652 The following functions are present:
653 fattach()
655 fdetach()
656 getmsg()
657 getpmsg()
658 ioctl()
659 isastream()
660 putmsg()
661 putpmsg()
662 XSI - _XOPEN_LEGACY - _SC_XOPEN_LEGACY
664 Functions included in the legacy option group were previously manda‐
665 tory, but are now optional in this version. The following functions
666 are present:
667 bcmp()
669 bcopy()
670 bzero()
671 ecvt()
672 fcvt()
673 ftime()
674 gcvt()
675 getwd()
676 index()
677 mktemp()
678 rindex()
679 utimes()
680 wcswcs()
681 XSI - _XOPEN_UNIX - _SC_XOPEN_UNIX
683 The following functions are present:
684 mmap()
686 munmap()
687 msync()
688 This option implies the following options:
690 _POSIX_FSYNC
692 _POSIX_MAPPED_FILES
693 _POSIX_MEMORY_PROTECTION
694 _POSIX_THREAD_ATTR_STACKADDR
695 _POSIX_THREAD_ATTR_STACKSIZE
696 _POSIX_THREAD_PROCESS_SHARED
697 _POSIX_THREAD_SAFE_FUNCTIONS
698 _POSIX_THREADS
699 This option may imply the following options from the XSI option groups:
701 Encryption (_XOPEN_CRYPT)
703 Realtime (_XOPEN_REALTIME)
704 Advanced Realtime (ADB)
705 Realtime Threads (_XOPEN_REALTIME_THREADS)
706 Advanced Realtime Threads (ADVANCED REALTIME THREADS)
707 Tracing (TRACING)
708 XSI Streams (STREAMS)
709 Legacy (_XOPEN_LEGACY)
710
712 sysconf(3), standards(7)
713Linux man-pages 6.04 2022-10-30 posixoptions(7)