NAME

       sigwait — select a set of signals

LIBRARY

       Standard C Library (libc, -lc)

SYNOPSIS

       #include <signal.h>

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

DESCRIPTION

       The  sigwait()  system  call 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()  atomically clears one of the selected signals from the set of pending signals (for the process
       or for the current thread) and sets the location pointed to by sig to the signal number that was cleared.

       The signals specified by set should be blocked at the time of the call to sigwait().

       If more than one thread is using sigwait() to wait for the same signal, no more than one of these threads
       will return from sigwait() with the signal number.  If more than a single thread is blocked in  sigwait()
       for  a  signal  when  that  signal  is  generated for the process, it is unspecified which of the waiting
       threads returns from sigwait().  If the signal is generated for a specific thread, as by  pthread_kill(),
       only that thread will return.

       Should  any of the multiple pending signals in the range SIGRTMIN to SIGRTMAX be selected, it will be the
       lowest numbered one.  The selection order between realtime and non-realtime signals, or between  multiple
       pending non-realtime signals, is unspecified.

IMPLEMENTATION NOTES

       The  sigwait() function is implemented as a wrapper around the __sys_sigwait() system call, which retries
       the call on EINTR error.

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

       The sigwait() system call will fail if:

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

SEE ALSO

       sigaction(2),  sigpending(2),  sigqueue(2),  sigsuspend(2),  sigtimedwait(2),  sigwaitinfo(2),  pause(3),
       pthread_sigmask(3)

STANDARDS

       The sigwait() function conforms to ISO/IEC 9945-1:1996 (“POSIX.1”).

Debian                                          September 6, 2013                                     SIGWAIT(2)