posixoptions.7 - Online Linux Manual Page

posixoptions - Online Linux Manual PageSection : 7
Updated : 2022-10-30
Source : Linux man-pages 6.03

NAMEposixoptions − optional parts of the POSIX standard

DESCRIPTIONThe POSIX standard (the information below is from POSIX.1-2001) describes a set of behaviors and interfaces for a compliant system. However, many interfaces are optional and there are feature test macros to test the availability of interfaces at compile time, and functions sysconf(3), fpathconf(3), pathconf(3), confstr(3) to do this at run time. From shell scripts one can use getconf(1). For more detail, see sysconf(3). We give the name of the POSIX abbreviation, the option, the name of the sysconf(3) parameter used to inquire about the option, and possibly a very short description. Much more precise detail can be found in the POSIX standard itself, versions of which can nowadays be accessed freely on the web.

ADV - _POSIX_ADVISORY_INFO - _SC_ADVISORY_INFOThe following advisory functions are present: posix_fadvise() posix_fallocate() posix_memalign() posix_madvise()

AIO - _POSIX_ASYNCHRONOUS_IO - _SC_ASYNCHRONOUS_IOThe header <aio.h> is present. The following functions are present: aio_cancel() aio_error() aio_fsync() aio_read() aio_return() aio_suspend() aio_write() lio_listio()

BAR - _POSIX_BARRIERS - _SC_BARRIERSThis option implies the _POSIX_THREADS and _POSIX_THREAD_SAFE_FUNCTIONS options. The following functions are present: pthread_barrier_destroy() pthread_barrier_init() pthread_barrier_wait() pthread_barrierattr_destroy() pthread_barrierattr_init()

--- - POSIX_CHOWN_RESTRICTEDIf this option is in effect (as it always is under POSIX.1-2001), then only root may change the owner of a file, and nonroot can set the group of a file only to one of the groups it belongs to. This affects the following functions chown() fchown()

CS - _POSIX_CLOCK_SELECTION - _SC_CLOCK_SELECTIONThis option implies the _POSIX_TIMERS option. The following functions are present: pthread_condattr_getclock() pthread_condattr_setclock() clock_nanosleep() If CLOCK_REALTIME is changed by the function clock_settime(), then this affects all timers set for an absolute time.

CPT - _POSIX_CPUTIME - _SC_CPUTIMEThe CLOCK_PROCESS_CPUTIME_ID clock ID is supported. The initial value of this clock is 0 for each process. This option implies the _POSIX_TIMERS option. The function clock_getcpuclockid() is present.

--- - _POSIX_FILE_LOCKING - _SC_FILE_LOCKINGThis option has been deleted. Not in final XPG6.

FSC - _POSIX_FSYNC - _SC_FSYNCThe function fsync() is present.

IP6 - _POSIX_IPV6 - _SC_IPV6Internet Protocol Version 6 is supported.

--- - _POSIX_JOB_CONTROL - _SC_JOB_CONTROLIf this option is in effect (as it always is under POSIX.1-2001), then the system implements POSIX-style job control, and the following functions are present: setpgid() tcdrain() tcflush() tcgetpgrp() tcsendbreak() tcsetattr() tcsetpgrp()

MF - _POSIX_MAPPED_FILES - _SC_MAPPED_FILESShared memory is supported. The include file <sys/mman.h> is present. The following functions are present: mmap() msync() munmap()

ML - _POSIX_MEMLOCK - _SC_MEMLOCKShared memory can be locked into core. The following functions are present: mlockall() munlockall()

MR/MLR - _POSIX_MEMLOCK_RANGE - _SC_MEMLOCK_RANGEMore precisely, ranges can be locked into core. The following functions are present: mlock() munlock()

MPR - _POSIX_MEMORY_PROTECTION - _SC_MEMORY_PROTECTIONThe function mprotect() is present.

MSG - _POSIX_MESSAGE_PASSING - _SC_MESSAGE_PASSINGThe include file <mqueue.h> is present. The following functions are present: mq_close() mq_getattr() mq_notify() mq_open() mq_receive() mq_send() mq_setattr() mq_unlink()

MON - _POSIX_MONOTONIC_CLOCK - _SC_MONOTONIC_CLOCKCLOCK_MONOTONIC is supported. This option implies the _POSIX_TIMERS option. The following functions are affected: aio_suspend() clock_getres() clock_gettime() clock_settime() timer_create()

--- - _POSIX_MULTI_PROCESS - _SC_MULTI_PROCESSThis option has been deleted. Not in final XPG6.

--- - _POSIX_NO_TRUNCIf this option is in effect (as it always is under POSIX.1-2001), then pathname components longer than NAME_MAX are not truncated, but give an error. This property may be dependent on the path prefix of the component.

PIO - _POSIX_PRIORITIZED_IO - _SC_PRIORITIZED_IOThis option says that one can specify priorities for asynchronous I/O. This affects the functions aio_read() aio_write()

PS - _POSIX_PRIORITY_SCHEDULING - _SC_PRIORITY_SCHEDULINGThe include file <sched.h> is present. The following functions are present: sched_get_priority_max() sched_get_priority_min() sched_getparam() sched_getscheduler() sched_rr_get_interval() sched_setparam() sched_setscheduler() sched_yield() If also _POSIX_SPAWN is in effect, then the following functions are present: posix_spawnattr_getschedparam() posix_spawnattr_getschedpolicy() posix_spawnattr_setschedparam() posix_spawnattr_setschedpolicy()

RS - _POSIX_RAW_SOCKETSRaw sockets are supported. The following functions are affected: getsockopt() setsockopt()

--- - _POSIX_READER_WRITER_LOCKS - _SC_READER_WRITER_LOCKSThis option implies the _POSIX_THREADS option. Conversely, under POSIX.1-2001 the _POSIX_THREADS option implies this option. The following functions are present: pthread_rwlock_destroy() pthread_rwlock_init() pthread_rwlock_rdlock() pthread_rwlock_tryrdlock() pthread_rwlock_trywrlock() pthread_rwlock_unlock() pthread_rwlock_wrlock() pthread_rwlockattr_destroy() pthread_rwlockattr_init()

RTS - _POSIX_REALTIME_SIGNALS - _SC_REALTIME_SIGNALSRealtime signals are supported. The following functions are present: sigqueue() sigtimedwait() sigwaitinfo()

--- - _POSIX_REGEXP - _SC_REGEXPIf this option is in effect (as it always is under POSIX.1-2001), then POSIX regular expressions are supported and the following functions are present: regcomp() regerror() regexec() regfree()

--- - _POSIX_SAVED_IDS - _SC_SAVED_IDSIf this option is in effect (as it always is under POSIX.1-2001), then a process has a saved set-user-ID and a saved set-group-ID. The following functions are affected: exec() kill() seteuid() setegid() setgid() setuid()

SEM - _POSIX_SEMAPHORES - _SC_SEMAPHORESThe include file <semaphore.h> is present. The following functions are present: sem_close() sem_destroy() sem_getvalue() sem_init() sem_open() sem_post() sem_trywait() sem_unlink() sem_wait()

SHM - _POSIX_SHARED_MEMORY_OBJECTS - _SC_SHARED_MEMORY_OBJECTSThe following functions are present: mmap() munmap() shm_open() shm_unlink()

--- - _POSIX_SHELL - _SC_SHELLIf this option is in effect (as it always is under POSIX.1-2001), the function system() is present.

SPN - _POSIX_SPAWN - _SC_SPAWNThis option describes support for process creation in a context where it is difficult or impossible to use fork(), for example, because no MMU is present. If _POSIX_SPAWN is in effect, then the include file <spawn.h> and the following functions are present: posix_spawn() posix_spawn_file_actions_addclose() posix_spawn_file_actions_adddup2() posix_spawn_file_actions_addopen() posix_spawn_file_actions_destroy() posix_spawn_file_actions_init() posix_spawnattr_destroy() posix_spawnattr_getsigdefault() posix_spawnattr_getflags() posix_spawnattr_getpgroup() posix_spawnattr_getsigmask() posix_spawnattr_init() posix_spawnattr_setsigdefault() posix_spawnattr_setflags() posix_spawnattr_setpgroup() posix_spawnattr_setsigmask() posix_spawnp() If also _POSIX_PRIORITY_SCHEDULING is in effect, then the following functions are present: posix_spawnattr_getschedparam() posix_spawnattr_getschedpolicy() posix_spawnattr_setschedparam() posix_spawnattr_setschedpolicy()

SPI - _POSIX_SPIN_LOCKS - _SC_SPIN_LOCKSThis option implies the _POSIX_THREADS and _POSIX_THREAD_SAFE_FUNCTIONS options. The following functions are present: pthread_spin_destroy() pthread_spin_init() pthread_spin_lock() pthread_spin_trylock() pthread_spin_unlock()

SS - _POSIX_SPORADIC_SERVER - _SC_SPORADIC_SERVERThe scheduling policy SCHED_SPORADIC is supported. This option implies the _POSIX_PRIORITY_SCHEDULING option. The following functions are affected: sched_setparam() sched_setscheduler()

SIO - _POSIX_SYNCHRONIZED_IO - _SC_SYNCHRONIZED_IOThe following functions are affected: open() msync() fsync() fdatasync()

TSA - _POSIX_THREAD_ATTR_STACKADDR - _SC_THREAD_ATTR_STACKADDRThe following functions are affected: pthread_attr_getstack() pthread_attr_getstackaddr() pthread_attr_setstack() pthread_attr_setstackaddr()

TSS - _POSIX_THREAD_ATTR_STACKSIZE - _SC_THREAD_ATTR_STACKSIZEThe following functions are affected: pthread_attr_getstack() pthread_attr_getstacksize() pthread_attr_setstack() pthread_attr_setstacksize()

TCT - _POSIX_THREAD_CPUTIME - _SC_THREAD_CPUTIMEThe clockID CLOCK_THREAD_CPUTIME_ID is supported. This option implies the _POSIX_TIMERS option. The following functions are affected: pthread_getcpuclockid() clock_getres() clock_gettime() clock_settime() timer_create()

TPI - _POSIX_THREAD_PRIO_INHERIT - _SC_THREAD_PRIO_INHERITThe following functions are affected: pthread_mutexattr_getprotocol() pthread_mutexattr_setprotocol()

TPP - _POSIX_THREAD_PRIO_PROTECT - _SC_THREAD_PRIO_PROTECTThe following functions are affected: pthread_mutex_getprioceiling() pthread_mutex_setprioceiling() pthread_mutexattr_getprioceiling() pthread_mutexattr_getprotocol() pthread_mutexattr_setprioceiling() pthread_mutexattr_setprotocol()

TPS - _POSIX_THREAD_PRIORITY_SCHEDULING - _SC_THREAD_PRIORITY_SCHEDULINGIf this option is in effect, the different threads inside a process can run with different priorities and/or different schedulers. The following functions are affected: pthread_attr_getinheritsched() pthread_attr_getschedpolicy() pthread_attr_getscope() pthread_attr_setinheritsched() pthread_attr_setschedpolicy() pthread_attr_setscope() pthread_getschedparam() pthread_setschedparam() pthread_setschedprio()

TSH - _POSIX_THREAD_PROCESS_SHARED - _SC_THREAD_PROCESS_SHAREDThe following functions are affected: pthread_barrierattr_getpshared() pthread_barrierattr_setpshared() pthread_condattr_getpshared() pthread_condattr_setpshared() pthread_mutexattr_getpshared() pthread_mutexattr_setpshared() pthread_rwlockattr_getpshared() pthread_rwlockattr_setpshared()

TSF - _POSIX_THREAD_SAFE_FUNCTIONS - _SC_THREAD_SAFE_FUNCTIONSThe following functions are affected: readdir_r() getgrgid_r() getgrnam_r() getpwnam_r() getpwuid_r() flockfile() ftrylockfile() funlockfile() getc_unlocked() getchar_unlocked() putc_unlocked() putchar_unlocked() rand_r() strerror_r() strtok_r() asctime_r() ctime_r() gmtime_r() localtime_r()

TSP - _POSIX_THREAD_SPORADIC_SERVER - _SC_THREAD_SPORADIC_SERVERThis option implies the _POSIX_THREAD_PRIORITY_SCHEDULING option. The following functions are affected: sched_getparam() sched_setparam() sched_setscheduler()

THR - _POSIX_THREADS - _SC_THREADSBasic support for POSIX threads is available. The following functions are present: pthread_atfork() pthread_attr_destroy() pthread_attr_getdetachstate() pthread_attr_getschedparam() pthread_attr_init() pthread_attr_setdetachstate() pthread_attr_setschedparam() pthread_cancel() pthread_cleanup_push() pthread_cleanup_pop() pthread_cond_broadcast() pthread_cond_destroy() pthread_cond_init() pthread_cond_signal() pthread_cond_timedwait() pthread_cond_wait() pthread_condattr_destroy() pthread_condattr_init() pthread_create() pthread_detach() pthread_equal() pthread_exit() pthread_getspecific() pthread_join() pthread_key_create() pthread_key_delete() pthread_mutex_destroy() pthread_mutex_init() pthread_mutex_lock() pthread_mutex_trylock() pthread_mutex_unlock() pthread_mutexattr_destroy() pthread_mutexattr_init() pthread_once() pthread_rwlock_destroy() pthread_rwlock_init() pthread_rwlock_rdlock() pthread_rwlock_tryrdlock() pthread_rwlock_trywrlock() pthread_rwlock_unlock() pthread_rwlock_wrlock() pthread_rwlockattr_destroy() pthread_rwlockattr_init() pthread_self() pthread_setcancelstate() pthread_setcanceltype() pthread_setspecific() pthread_testcancel()

TMO - _POSIX_TIMEOUTS - _SC_TIMEOUTSThe following functions are present: mq_timedreceive() mq_timedsend() pthread_mutex_timedlock() pthread_rwlock_timedrdlock() pthread_rwlock_timedwrlock() sem_timedwait() posix_trace_timedgetnext_event()

TMR - _POSIX_TIMERS - _SC_TIMERSThe following functions are present: clock_getres() clock_gettime() clock_settime() nanosleep() timer_create() timer_delete() timer_gettime() timer_getoverrun() timer_settime()

TEF - _POSIX_TRACE_EVENT_FILTER - _SC_TRACE_EVENT_FILTERThis option implies the _POSIX_TRACE option. The following functions are present: posix_trace_eventset_add() posix_trace_eventset_del() posix_trace_eventset_empty() posix_trace_eventset_fill() posix_trace_eventset_ismember() posix_trace_get_filter() posix_trace_set_filter() posix_trace_trid_eventid_open()

TRI - _POSIX_TRACE_INHERIT - _SC_TRACE_INHERITTracing children of the traced process is supported. This option implies the _POSIX_TRACE option. The following functions are present: posix_trace_attr_getinherited() posix_trace_attr_setinherited()

TRL - _POSIX_TRACE_LOG - _SC_TRACE_LOGThis option implies the _POSIX_TRACE option. The following functions are present: posix_trace_attr_getlogfullpolicy() posix_trace_attr_getlogsize() posix_trace_attr_setlogfullpolicy() posix_trace_attr_setlogsize() posix_trace_close() posix_trace_create_withlog() posix_trace_open() posix_trace_rewind()

TYM - _POSIX_TYPED_MEMORY_OBJECTS - _SC_TYPED_MEMORY_OBJECTThe following functions are present: posix_mem_offset() posix_typed_mem_get_info() posix_typed_mem_open()

--- - _POSIX_VDISABLEAlways present (probably 0). Value to set a changeable special control character to indicate that it is disabled.

X/OPEN SYSTEM INTERFACE EXTENSIONS

XSI - _XOPEN_CRYPT - _SC_XOPEN_CRYPTThe following functions are present: crypt() encrypt() setkey()

XSI - _XOPEN_REALTIME - _SC_XOPEN_REALTIMEThis option implies the following options: _POSIX_ASYNCHRONOUS_IO==200112L _POSIX_FSYNC _POSIX_MAPPED_FILES _POSIX_MEMLOCK==200112L _POSIX_MEMLOCK_RANGE==200112L _POSIX_MEMORY_PROTECTION _POSIX_MESSAGE_PASSING==200112L _POSIX_PRIORITIZED_IO _POSIX_PRIORITY_SCHEDULING==200112L _POSIX_REALTIME_SIGNALS==200112L _POSIX_SEMAPHORES==200112L _POSIX_SHARED_MEMORY_OBJECTS==200112L _POSIX_SYNCHRONIZED_IO==200112L _POSIX_TIMERS==200112L

ADV - --- - ---The Advanced Realtime option group implies that the following options are all defined to 200112L: _POSIX_ADVISORY_INFO _POSIX_CLOCK_SELECTION (implies _POSIX_TIMERS) _POSIX_CPUTIME (implies _POSIX_TIMERS) _POSIX_MONOTONIC_CLOCK (implies _POSIX_TIMERS) _POSIX_SPAWN _POSIX_SPORADIC_SERVER (implies _POSIX_PRIORITY_SCHEDULING) _POSIX_TIMEOUTS _POSIX_TYPED_MEMORY_OBJECTS

XSI - _XOPEN_REALTIME_THREADS - _SC_XOPEN_REALTIME_THREADSThis option implies that the following options are all defined to 200112L: _POSIX_THREAD_PRIO_INHERIT _POSIX_THREAD_PRIO_PROTECT _POSIX_THREAD_PRIORITY_SCHEDULING

ADVANCED REALTIME THREADS - --- - ---This option implies that the following options are all defined to 200112L: _POSIX_BARRIERS (implies _POSIX_THREADS, _POSIX_THREAD_SAFE_FUNCTIONS) _POSIX_SPIN_LOCKS (implies _POSIX_THREADS, _POSIX_THREAD_SAFE_FUNCTIONS) _POSIX_THREAD_CPUTIME (implies _POSIX_TIMERS) _POSIX_THREAD_SPORADIC_SERVER (implies _POSIX_THREAD_PRIORITY_SCHEDULING)

TRACING - --- - ---This option implies that the following options are all defined to 200112L: _POSIX_TRACE _POSIX_TRACE_EVENT_FILTER _POSIX_TRACE_LOG _POSIX_TRACE_INHERIT

STREAMS - _XOPEN_STREAMS - _SC_XOPEN_STREAMSThe following functions are present: fattach() fdetach() getmsg() getpmsg() ioctl() isastream() putmsg() putpmsg()

XSI - _XOPEN_LEGACY - _SC_XOPEN_LEGACYFunctions included in the legacy option group were previously mandatory, but are now optional in this version. The following functions are present: bcmp() bcopy() bzero() ecvt() fcvt() ftime() gcvt() getwd() index() mktemp() rindex() utimes() wcswcs()

XSI - _XOPEN_UNIX - _SC_XOPEN_UNIXThe following functions are present: mmap() munmap() msync() This option implies the following options: _POSIX_FSYNC _POSIX_MAPPED_FILES _POSIX_MEMORY_PROTECTION _POSIX_THREAD_ATTR_STACKADDR _POSIX_THREAD_ATTR_STACKSIZE _POSIX_THREAD_PROCESS_SHARED _POSIX_THREAD_SAFE_FUNCTIONS _POSIX_THREADS This option may imply the following options from the XSI option groups: Encryption (_XOPEN_CRYPT) Realtime (_XOPEN_REALTIME) Advanced Realtime (ADB) Realtime Threads (_XOPEN_REALTIME_THREADS) Advanced Realtime Threads (ADVANCED REALTIME THREADS) Tracing (TRACING) XSI Streams (STREAMS) Legacy (_XOPEN_LEGACY)