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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 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 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 3.32 of the Linux man-pages project.  A
       description of the project, and information about reporting bugs, can be found
       at http://www.kernel.org/doc/man-pages/.

                                      2007-12-21                      POSIXOPTIONS(7)

HTML rendering created 2010-12-03 by Michael Kerrisk, author of The Linux Programming Interface