NAME | DESCRIPTION | XOPEN EXTENSIONS | SEE ALSO | COLOPHON

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

NAME         top

       posixoptions - optional parts of the POSIX standard

DESCRIPTION         top

       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), 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_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 nonroot can set
       the group of a file only 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 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.

XOPEN EXTENSIONS         top

       _XOPEN_CRYPT, _XOPEN_LEGACY, _XOPEN_REALTIME,
       _XOPEN_REALTIME_THREADS, _XOPEN_UNIX.

SEE ALSO         top

       sysconf(3), standards(7)

COLOPHON         top

       This page is part of release 4.07 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/.

                                 2007-12-21                  POSIXOPTIONS(7)