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NAME

       posixoptions - optional parts of the POSIX standard

DESCRIPTION

       The  POSIX  standard  (the information below is from POSIX 1003.1-2001)
       describes a set of behaviours 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() 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 advisory functions
           posix_fadvise(),
           posix_fallocate(),
           posix_memalign(),
           posix_madvise()
       are present.

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

   BAR - _POSIX_BARRIERS - _SC_BARRIERS
       This option implies the _POSIX_THREADS and _POSIX_THREAD_SAFE_FUNCTIONS
       options.  The functions
           pthread_barrier_destroy(),
           pthread_barrier_init(),
           pthread_barrier_wait(),
           pthread_barrierattr_destroy(),
           pthread_barrierattr_init()
       are present.

   --- - POSIX_CHOWN_RESTRICTED
       If this option is in effect (as it always is under  POSIX  1003.1-2001)
       then  only  root  may change the owner of a file, and non-root can only
       set the group of a file to one of  the  groups  it  belongs  to.   This
       affects the functions chown(), fchown().

   CS - _POSIX_CLOCK_SELECTION - _SC_CLOCK_SELECTION
       This option implies the _POSIX_TIMERS option.  The functions
           pthread_condattr_getclock(),
           pthread_condattr_setclock(),
           clock_nanosleep()
       are   present.    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  clockID  CLOCK_PROCESS_CPUTIME_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_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 1003.1-2001)
       then the system implements POSIX-style job control, and the functions
           setpgid(),
           tcdrain(),
           tcflush(),
           tcgetpgrp(),
           tcsendbreak(),
           tcsetattr(),
           tcsetpgrp()
       are present.

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

   ML - _POSIX_MEMLOCK - _SC_MEMLOCK
       Shared  memory  can  be  locked  into  core.  The functions mlockall(),
       munlockall() are present.

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

   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 functions
           mq_close(),
           mq_getattr(),
           mq_notify(),
           mq_open(),
           mq_receive(),
           mq_send(),
           mq_setattr(),
           mq_unlink()
       are present.

   MON - _POSIX_MONOTONIC_CLOCK - _SC_MONOTONIC_CLOCK
       CLOCK_MONOTONIC is supported.
       This option implies the _POSIX_TIMERS option.
       Affected functions are
           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 1003.1-2001)
       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 functions
           sched_get_priority_max(),
           sched_get_priority_min(),
           sched_getparam(),
           sched_getscheduler(),
           sched_rr_get_interval(),
           sched_setparam(),
           sched_setscheduler(),
           sched_yield()
       are present.  If also _POSIX_SPAWN is in effect, then the functions
           posix_spawnattr_getschedparam(),
           posix_spawnattr_getschedpolicy(),
           posix_spawnattr_setschedparam(),
           posix_spawnattr_setschedpolicy()
       are present.

   RS - _POSIX_RAW_SOCKETS
       Raw   sockets  are  supported.  Affected  functions  are  getsockopt(),
       setsockopt().

   --- - _POSIX_READER_WRITER_LOCKS - _SC_READER_WRITER_LOCKS
       This option implies the _POSIX_THREADS option. Conversely, under  POSIX
       1003.1-2001 the _POSIX_THREADS option implies this option.
       The functions
           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()
       are present.

   RTS - _POSIX_REALTIME_SIGNALS - _SC_REALTIME_SIGNALS
       Realtime signals are supported. The functions
           sigqueue(),
           sigtimedwait(),
           sigwaitinfo()
       are present.

   --- - _POSIX_REGEXP - _SC_REGEXP
       If  this  option is in effect (as it always is under POSIX 1003.1-2001)
       then POSIX regular expressions are supported and the functions
           regcomp(),
           regerror(),
           regexec(),
           regfree()
       are present.

   --- - _POSIX_SAVED_IDS - _SC_SAVED_IDS
       If this option is in effect (as it always is under  POSIX  1003.1-2001)
       then  a  process  has  a  saved  set-user-ID  and a saved set-group-ID.
       Affected functions are
           exec(),
           kill(),
           seteuid(),
           setegid(),
           setgid(),
           setuid().

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

   SHM - _POSIX_SHARED_MEMORY_OBJECTS - _SC_SHARED_MEMORY_OBJECTS
       The functions
           mmap(),
           munmap(),
           shm_open(),
           shm_unlink()
       are present.

   --- - _POSIX_SHELL - _SC_SHELL
       If this option is in effect (as it always is under POSIX  1003.1-2001),
       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 impossible to use fork(), e.g.  because  no  MMU  is
       present.  If _POSIX_SPAWN is in effect, then the include file <spawn.h>
       and the functions
           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()
       are present.  If also _POSIX_PRIORITY_SCHEDULING is in effect, then the
       functions
           posix_spawnattr_getschedparam(),
           posix_spawnattr_getschedpolicy(),
           posix_spawnattr_setschedparam(),
           posix_spawnattr_setschedpolicy()
       are present.

   SPI - _POSIX_SPIN_LOCKS - _SC_SPIN_LOCKS
       This option implies the _POSIX_THREADS and _POSIX_THREAD_SAFE_FUNCTIONS
       options.  The functions
           pthread_spin_destroy(),
           pthread_spin_init(),
           pthread_spin_lock(),
           pthread_spin_trylock(),
           pthread_spin_unlock()
       are present.

   SS - _POSIX_SPORADIC_SERVER - _SC_SPORADIC_SERVER
       The scheduling policy SCHED_SPORADIC is supported.  This option implies
       the _POSIX_PRIORITY_SCHEDULING option.  Affected functions are
           sched_setparam(),
           sched_setscheduler().

   SIO - _POSIX_SYNCHRONIZED_IO - _SC_SYNCHRONIZED_IO
       Affected functions are open(), msync(), fsync(), fdatasync().

   TSA - _POSIX_THREAD_ATTR_STACKADDR - _SC_THREAD_ATTR_STACKADDR
       Affected functions are
           pthread_attr_getstack(),
           pthread_attr_getstackaddr(),
           pthread_attr_setstack(),
           pthread_attr_setstackaddr().

   TSS - _POSIX_THREAD_ATTR_STACKSIZE - _SC_THREAD_ATTR_STACKSIZE
       Affected functions are
           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 option.  Affected functions are
           pthread_getcpuclockid(),
           clock_getres(),
           clock_gettime(),
           clock_settime(),
           timer_create().

   TPI - _POSIX_THREAD_PRIO_INHERIT - _SC_THREAD_PRIO_INHERIT
       Affected functions are
           pthread_mutexattr_getprotocol(),
           pthread_mutexattr_setprotocol().

   TPP - _POSIX_THREAD_PRIO_PROTECT - _SC_THREAD_PRIO_PROTECT
       Affected functions are
           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.  Affected
       functions are
           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
       Affected functions are
           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
       Affected functions are
           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.
       Affected functions are
           sched_getparam(),
           sched_setparam(),
           sched_setscheduler().

   THR - _POSIX_THREADS - _SC_THREADS
       Basic support for POSIX threads is available. The functions
           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()
       are present.

   TMO - _POSIX_TIMEOUTS - _SC_TIMEOUTS
       The functions
           mq_timedreceive(),
           mq_timedsend(),
           pthread_mutex_timedlock(),
           pthread_rwlock_timedrdlock(),
           pthread_rwlock_timedwrlock(),
           sem_timedwait(),
           posix_trace_timedgetnext_event()
       are present.

   TMR - _POSIX_TIMERS - _SC_TIMERS
       The functions
           clock_getres(),
           clock_gettime(),
           clock_settime(),
           nanosleep(),
           timer_create(),
           timer_delete(),
           timer_gettime(),
           timer_getoverrun(),
           timer_settime()
       are present.

   TRC - _POSIX_TRACE - _SC_TRACE
       POSIX tracing is available. The functions
           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()
       are present.

   TEF - _POSIX_TRACE_EVENT_FILTER - _SC_TRACE_EVENT_FILTER
       This option implies the _POSIX_TRACE option.  The functions
           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()
       are present.

   TRI - _POSIX_TRACE_INHERIT - _SC_TRACE_INHERIT
       Tracing  children  of  the  traced  process  is supported.  This option
       implies the _POSIX_TRACE option.  The functions
           posix_trace_attr_getinherited(),
           posix_trace_attr_setinherited()
       are present.

   TRL - _POSIX_TRACE_LOG - _SC_TRACE_LOG
       This option implies the _POSIX_TRACE option.  The functions
           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()
       are present.

   TYM - _POSIX_TYPED_MEMORY_OBJECTS - _SC_TYPED_MEMORY_OBJECT
       The functions
           posix_mem_offset(),
           posix_typed_mem_get_info(),
           posix_typed_mem_open()
       are present.

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

XOPEN EXTENSIONS

       _XOPEN_CRYPT,  _XOPEN_LEGACY, _XOPEN_REALTIME, _XOPEN_REALTIME_THREADS,
       _XOPEN_UNIX.

SEE ALSO

       sysconf(3)