sigwait(2)                                                   sigwait(2)

  sigwait()

  NAME

    sigwait() - wait for a pending signal

  SYNOPSIS

    #include 

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

  DESCRIPTION

    The sigwait(2) function selects a pending signal in the signal set
    referenced by the set argument, clears the signal from the set, and stores
    the number of the signal in the location referenced by the sig argument
    before returning. If set does not contain a pending signal, then
    sigwait(2) suspends the calling thread or process until at least one
    pending signal is added to the set.

    If multiple threads are suspended by sigwait(2) waiting for the same
    signal, sigwait(2) returns the number of the signal to only one thread.

  RETURN VALUE

    Upon successful completion, the sigwait(2) function returns 0 and stores
    the signal number of the pending signal that it cleared from the signal
    set in sig. Otherwise, it returns -1 and sets errno to indicate the error.

  ERRORS

    The sigwait(2) function can fail for the following reason:

    [EINTR]
        The wait was interrupted by an unblocked caught signal.

    [EINVAL]
        The signal set referenced by set contains an invalid or illegal signal
        number.

  SEE ALSO

    pause(2)

    pthread_sigmask(2)

    sigaction(2)

    signal(2)

    sigpending(2)

    sigprocmask(2)

    sigsuspend(2)

  USAGE NOTES

    The sigwait function is thread safe.

    The sigwait function is not async-signal safe.