# man > POSIXOPTIONS(7)

[POSIXOPTIONS(7)](https://www.chedong.com/phpMan.php/man/POSIXOPTIONS/7/markdown)                       Linux Programmer's Manual                      [POSIXOPTIONS(7)](https://www.chedong.com/phpMan.php/man/POSIXOPTIONS/7/markdown)



## NAME
       posixoptions - optional parts of the POSIX standard

## DESCRIPTION
       The  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)](https://www.chedong.com/phpMan.php/man/sysconf/3/markdown), [**fpathconf**(3)](https://www.chedong.com/phpMan.php/man/fpathconf/3/markdown), [**pathconf**(3)](https://www.chedong.com/phpMan.php/man/pathconf/3/markdown), [**confstr**(3)](https://www.chedong.com/phpMan.php/man/confstr/3/markdown) to do this at run time.  From shell scripts
       one can use [**getconf**(1)](https://www.chedong.com/phpMan.php/man/getconf/1/markdown).  For more detail, see [**sysconf**(3)](https://www.chedong.com/phpMan.php/man/sysconf/3/markdown).

       We  give the name of the POSIX abbreviation, the option, the name of the [**sysconf**(3)](https://www.chedong.com/phpMan.php/man/sysconf/3/markdown) 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**___**INFO**
       The following advisory functions are present:

           _posix_fadvise_()
           _posix_fallocate_()
           _posix_memalign_()
           _posix_madvise_()

   **AIO** **-** ___**POSIX**___**ASYNCHRONOUS**___**IO** **-** ___**SC**___**ASYNCHRONOUS**___**IO**
       The 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**___**BARRIERS**
       This option implies the ___**POSIX**___**THREADS** and ___**POSIX**___**THREAD**___**SAFE**___**FUNCTIONS** options.  The follow‐
       ing functions are present:

           _pthread_barrier_destroy_()
           _pthread_barrier_init_()
           _pthread_barrier_wait_()
           _pthread_barrierattr_destroy_()
           _pthread_barrierattr_init_()

   **---** **-** **POSIX**___**CHOWN**___**RESTRICTED**
       If  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 be‐
       longs to.  This affects the following functions

           _chown_()
           _fchown_()

   **CS** **-** ___**POSIX**___**CLOCK**___**SELECTION** **-** ___**SC**___**CLOCK**___**SELECTION**
       This 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**___**CPUTIME**
       The **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_getcpu__‐
       _clockid_() is present.

   **---** **-** ___**POSIX**___**FILE**___**LOCKING** **-** ___**SC**___**FILE**___**LOCKING**
       This option has been deleted.  Not in final XPG6.

   **FSC** **-** ___**POSIX**___**FSYNC** **-** ___**SC**___**FSYNC**
       The function _fsync_() is present.

   **IP6** **-** ___**POSIX**___**IPV6** **-** ___**SC**___**IPV6**
       Internet Protocol Version 6 is supported.

   **---** **-** ___**POSIX**___**JOB**___**CONTROL** **-** ___**SC**___**JOB**___**CONTROL**
       If 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**___**FILES**
       Shared  memory  is supported.  The include file _<sys/mman.h>_ is present.  The following func‐
       tions are present:

           _mmap_()
           _msync_()
           _munmap_()

   **ML** **-** ___**POSIX**___**MEMLOCK** **-** ___**SC**___**MEMLOCK**
       Shared memory can be locked into core.  The following functions are present:

           _mlockall_()
           _munlockall_()

   **MR/MLR** **-** ___**POSIX**___**MEMLOCK**___**RANGE** **-** ___**SC**___**MEMLOCK**___**RANGE**
       More precisely, ranges can be locked into core.  The following functions are present:

           _mlock_()
           _munlock_()

   **MPR** **-** ___**POSIX**___**MEMORY**___**PROTECTION** **-** ___**SC**___**MEMORY**___**PROTECTION**
       The function _mprotect_() is present.

   **MSG** **-** ___**POSIX**___**MESSAGE**___**PASSING** **-** ___**SC**___**MESSAGE**___**PASSING**
       The 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**___**CLOCK**
       **CLOCK**___**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**___**PROCESS**
       This option has been deleted.  Not in final XPG6.

   **---** **-** ___**POSIX**___**NO**___**TRUNC**
       If  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**___**IO**
       This  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**___**SCHEDULING**
       The 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**___**SOCKETS**
       Raw sockets are supported.  The following functions are affected:

           _getsockopt_()
           _setsockopt_()

   **---** **-** ___**POSIX**___**READER**___**WRITER**___**LOCKS** **-** ___**SC**___**READER**___**WRITER**___**LOCKS**
       This  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**___**SIGNALS**
       Realtime signals are supported.  The following functions are present:

           _sigqueue_()
           _sigtimedwait_()
           _sigwaitinfo_()

   **---** **-** ___**POSIX**___**REGEXP** **-** ___**SC**___**REGEXP**
       If  this option is in effect (as it always is under POSIX.1-2001), then POSIX regular expres‐
       sions are supported and the following functions are present:

           _regcomp_()
           _regerror_()
           _regexec_()
           _regfree_()

   **---** **-** ___**POSIX**___**SAVED**___**IDS** **-** ___**SC**___**SAVED**___**IDS**
       If 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**___**SEMAPHORES**
       The 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**___**OBJECTS**
       The following functions are present:

           _mmap_()
           _munmap_()
           _shm_open_()
           _shm_unlink_()

   **---** **-** ___**POSIX**___**SHELL** **-** ___**SC**___**SHELL**
       If  this  option  is in effect (as it always is under POSIX.1-2001), the function _system_() is
       present.

   **SPN** **-** ___**POSIX**___**SPAWN** **-** ___**SC**___**SPAWN**
       This option describes support for process creation in a context where it is difficult or  im‐
       possible 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**___**LOCKS**
       This option implies the ___**POSIX**___**THREADS** and ___**POSIX**___**THREAD**___**SAFE**___**FUNCTIONS** options.  The follow‐
       ing functions are present:

           _pthread_spin_destroy_()
           _pthread_spin_init_()
           _pthread_spin_lock_()
           _pthread_spin_trylock_()
           _pthread_spin_unlock_()

   **SS** **-** ___**POSIX**___**SPORADIC**___**SERVER** **-** ___**SC**___**SPORADIC**___**SERVER**
       The  scheduling  policy  **SCHED**___**SPORADIC**  is supported.  This option implies the ___**POSIX**___**PRIOR**‐‐
       **ITY**___**SCHEDULING** option.  The following functions are affected:

           _sched_setparam_()
           _sched_setscheduler_()

   **SIO** **-** ___**POSIX**___**SYNCHRONIZED**___**IO** **-** ___**SC**___**SYNCHRONIZED**___**IO**
       The following functions are affected:

           _open_()
           _msync_()
           _fsync_()
           _fdatasync_()

   **TSA** **-** ___**POSIX**___**THREAD**___**ATTR**___**STACKADDR** **-** ___**SC**___**THREAD**___**ATTR**___**STACKADDR**
       The following functions are affected:

           _pthread_attr_getstack_()
           _pthread_attr_getstackaddr_()
           _pthread_attr_setstack_()
           _pthread_attr_setstackaddr_()

   **TSS** **-** ___**POSIX**___**THREAD**___**ATTR**___**STACKSIZE** **-** ___**SC**___**THREAD**___**ATTR**___**STACKSIZE**
       The following functions are affected:

           _pthread_attr_getstack_()
           _pthread_attr_getstacksize_()
           _pthread_attr_setstack_()
           _pthread_attr_setstacksize_()

   **TCT** **-** ___**POSIX**___**THREAD**___**CPUTIME** **-** ___**SC**___**THREAD**___**CPUTIME**
       The clockID CLOCK_THREAD_CPUTIME_ID is supported.  This option implies the ___**POSIX**___**TIMERS**  op‐
       tion.  The following functions are affected:

           _pthread_getcpuclockid_()
           _clock_getres_()
           _clock_gettime_()
           _clock_settime_()
           _timer_create_()

   **TPI** **-** ___**POSIX**___**THREAD**___**PRIO**___**INHERIT** **-** ___**SC**___**THREAD**___**PRIO**___**INHERIT**
       The following functions are affected:

           _pthread_mutexattr_getprotocol_()
           _pthread_mutexattr_setprotocol_()

   **TPP** **-** ___**POSIX**___**THREAD**___**PRIO**___**PROTECT** **-** ___**SC**___**THREAD**___**PRIO**___**PROTECT**
       The 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**___**SCHEDULING**
       If  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**___**SHARED**
       The 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**___**FUNCTIONS**
       The 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**___**SERVER**
       This option implies the ___**POSIX**___**THREAD**___**PRIORITY**___**SCHEDULING** option.   The  following  functions
       are affected:

           _sched_getparam_()
           _sched_setparam_()
           _sched_setscheduler_()

   **THR** **-** ___**POSIX**___**THREADS** **-** ___**SC**___**THREADS**
       Basic 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**___**TIMEOUTS**
       The 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**___**TIMERS**
       The following functions are present:

           _clock_getres_()
           _clock_gettime_()
           _clock_settime_()
           _nanosleep_()
           _timer_create_()
           _timer_delete_()
           _timer_gettime_()
           _timer_getoverrun_()
           _timer_settime_()

   **TRC** **-** ___**POSIX**___**TRACE** **-** ___**SC**___**TRACE**
       POSIX tracing is available.  The following functions are present:

           _posix_trace_attr_destroy_()
           _posix_trace_attr_getclockres_()
           _posix_trace_attr_getcreatetime_()
           _posix_trace_attr_getgenversion_()
           _posix_trace_attr_getmaxdatasize_()
           _posix_trace_attr_getmaxsystemeventsize_()
           _posix_trace_attr_getmaxusereventsize_()
           _posix_trace_attr_getname_()
           _posix_trace_attr_getstreamfullpolicy_()
           _posix_trace_attr_getstreamsize_()
           _posix_trace_attr_init_()
           _posix_trace_attr_setmaxdatasize_()
           _posix_trace_attr_setname_()
           _posix_trace_attr_setstreamsize_()
           _posix_trace_attr_setstreamfullpolicy_()
           _posix_trace_clear_()
           _posix_trace_create_()
           _posix_trace_event_()
           _posix_trace_eventid_equal_()
           _posix_trace_eventid_get_name_()
           _posix_trace_eventid_open_()
           _posix_trace_eventtypelist_getnext_id_()
           _posix_trace_eventtypelist_rewind_()
           _posix_trace_flush_()
           _posix_trace_get_attr_()
           _posix_trace_get_status_()
           _posix_trace_getnext_event_()
           _posix_trace_shutdown_()
           _posix_trace_start_()
           _posix_trace_stop_()
           _posix_trace_trygetnext_event_()

   **TEF** **-** ___**POSIX**___**TRACE**___**EVENT**___**FILTER** **-** ___**SC**___**TRACE**___**EVENT**___**FILTER**
       This 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**___**INHERIT**
       Tracing  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**___**LOG**
       This 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**___**OBJECT**
       The following functions are present:

           _posix_mem_offset_()
           _posix_typed_mem_get_info_()
           _posix_typed_mem_open_()

   **---** **-** ___**POSIX**___**VDISABLE**
       Always 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**___**CRYPT**
       The following functions are present:

           _crypt_()
           _encrypt_()
           _setkey_()

   **XSI** **-** ___**XOPEN**___**REALTIME** **-** ___**SC**___**XOPEN**___**REALTIME**
       This 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**___**THREADS**
       This 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**___**STREAMS**
       The following functions are present:

           _fattach_()
           _fdetach_()
           _getmsg_()
           _getpmsg_()
           _ioctl_()
           _isastream_()
           _putmsg_()
           _putpmsg_()

   **XSI** **-** ___**XOPEN**___**LEGACY** **-** ___**SC**___**XOPEN**___**LEGACY**
       Functions 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_()
           _getcwd_()
           _index_()
           _mktemp_()
           _rindex_()
           _utimes_()
           _wcswcs_()

   **XSI** **-** ___**XOPEN**___**UNIX** **-** ___**SC**___**XOPEN**___**UNIX**
       The 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**)

## SEE ALSO
       [**sysconf**(3)](https://www.chedong.com/phpMan.php/man/sysconf/3/markdown), [**standards**(7)](https://www.chedong.com/phpMan.php/man/standards/7/markdown)

## COLOPHON
       This  page  is  part  of  release  5.10 of the Linux _man-pages_ project.  A description of the
       project, information about reporting bugs, and the latest version of this page, can be  found
       at <https://www.kernel.org/doc/man-pages/>.



                                             2018-04-30                              [POSIXOPTIONS(7)](https://www.chedong.com/phpMan.php/man/POSIXOPTIONS/7/markdown)