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POSIXOPTIONS(7)            Linux Programmer's Manual           POSIXOPTIONS(7)



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 avail-
       ability  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 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 following  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 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 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 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.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  functions  are  present:
       mmap(), msync(), munmap().

   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 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.  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.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.  Affected functions are 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 expressions 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.  Affected functions are

           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 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_LOCKS
       This  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_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 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 follow-
       ing 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  dis-
       abled.

XOPEN EXTENSIONS
       _XOPEN_CRYPT, _XOPEN_LEGACY, _XOPEN_REALTIME, _XOPEN_REALTIME_THREADS, _XOPEN_UNIX.

SEE ALSO
       sysconf(3), standards(7)

COLOPHON
       This  page  is part of release 3.22 of the Linux man-pages project.  A description of the project, and informa-
       tion about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



                                  2007-12-21                   POSIXOPTIONS(7)