*** UNIX MANUAL PAGE BROWSER ***

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 stan- dards as follows: sigsuspend(): XPG4, XPG4-UNIX Refer to the standards(5) reference page for more information about in- dustry 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 sig- nal 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 indica- tion of the error; the illegal request is simply ignored. If delivery of a signal causes the process to terminate, the sigsus- pend() function does not return. If delivery of a signal causes a sig- nal-catching function to execute, the sigsuspend() function returns af- ter 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 un- blocked signal as one atomic operation. This means that signals cannot occur between the operations of setting the mask and waiting for a sig- nal. If a program invokes sigprocmask(SIG_SETMASK) and sigpause() sep- arately, a signal that occurs between these functions might not be no- ticed by sigpause(). In normal usage, a signal is blocked by using the sigproc- mask(SIG_BLOCK,...) or pthread_sigmask(...) function at the beginning of a critical 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 calling 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 indefi- nitely, 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)