sigsuspend(2)							System Calls Manual						     sigsuspend(2)

NAME

       sigsuspend - Atomically changes the set of blocked signals and waits for a signal

LIBRARY

       Standard C Library (libc.so, libc.a)

SYNOPSIS

       #include <signal.h>

       int sigsuspend (
	       const sigset_t *signal_mask );

STANDARDS

       Interfaces documented on this reference page conform to industry standards as follows:

       sigsuspend():  XPG4, XPG4-UNIX

       Refer to the standards(5) reference page for more information about industry standards and associated tags.

PARAMETERS

       Points to a set of signals.

DESCRIPTION

       The sigsuspend() function replaces the signal mask of the process (or thread) with the set of signals pointed to by the signal_mask parame-
       ter, and then suspends execution of the caller until delivery of a signal whose action is either to execute a signal-catching  function	or
       to terminate the process.  The sigsuspend() function does not allow the SIGKILL or SIGSTOP signals to be blocked.  If a program attempts to
       block one of these signals, the sigsuspend() function gives no indication of the error; the illegal request is simply ignored.

       If delivery of a signal causes the process to terminate, the sigsuspend() function does not return. If delivery of a signal causes  a  sig-
       nal-catching  function  to  execute,  the  sigsuspend()	function  returns after the signal-catching function returns, with the signal mask
       restored to the set that existed prior to the call to the sigsuspend() function.

       The sigsuspend() function sets the signal mask and waits for an unblocked signal as one atomic operation. This means  that  signals  cannot
       occur  between  the  operations of setting the mask and waiting for a signal.  If a program invokes sigprocmask(SIG_SETMASK) and sigpause()
       separately, a signal that occurs between these functions might not be noticed by sigpause().

       In normal usage, a signal is blocked by using the sigprocmask(SIG_BLOCK,...)  or pthread_sigmask(...)  function at the beginning of a crit-
       ical section. The process then determines whether there is work for it to do. If no work is to be done, the process waits for work by call-
       ing the sigsuspend() function with the mask previously returned by the sigprocmask() function.

NOTES

       The sigpause() function is provided for compatibility with older UNIX systems; its function is a subset of the sigsuspend() function.

RETURN VALUES

       Since the sigsuspend() function suspends process execution indefinitely, there is no successful	completion  return  value.   If  a  return
       occurs, -1 is returned and errno is set to indicate the error.

ERRORS

       The  sigsuspend()  function  sets errno to the specified values for the following conditions: A signal is caught by the calling process and
       control is returned from the signal-catching function.

RELATED INFORMATION

       Functions: pause(3), sigaction(2), sigblock(2), sigprocmask(2), sigvec(2)

       Standards: standards(5) delim off

																     sigsuspend(2)