int
     sigwait(const sigset_t *set, int *sig);

DESCRIPTION

     The sigwait() function selects a set of signals, specified by set.  If
     none of the selected signals are pending, sigwait() waits until one or
     more of the selected signals has been generated.  Then sigwait() atomi-
     cally clears one of the selected signals from the set of pending signals
     for the process and sets the location pointed to by sig to the signal
     number that was cleared.

     The signals specified by set should be blocked, but not ignored, at the
     time of the call to sigwait().

     Processes which call sigwait() on ignored signals will wait indefinately.
     Ignored signals are dropped immeadiately by the system, before delivery
     to a waiting process.

RETURN VALUES

     If successful, sigwait() returns 0 and sets the location pointed to by
     sig to the cleared signal number.  Otherwise, an error number is
     returned.

ERRORS

     sigwait() will fail if:

     [EINVAL]           set specifies one or more invalid signal numbers.

SEE ALSO

     sigaction(2), sigpending(2), sigsuspend(2), pause(3), pthread_sigmask(2)

STANDARDS

     sigwait() conforms to ISO/IEC 9945-1:1996 (``POSIX.1'')

BSD                             April 27, 2000                             BSD