sigdelset - delete signal from signal set

Syntax	#include <signal.h> int sigdelset(sigset_t *set, int sig);
Description	sigdelset() deletes the signal sig from the signal set pointed to by setgt.
Return val.	0	if successful.
	-1	if an error occurs. errno is set to indicate the error.
Errors	sigdelset() will fail if:
	EINVAL	The value of sig is an invalid or unsupported signal number.
Notes	Applications should call sigemptyset() or sigfillset() for each object of type sigset_t prior to any other use of that object. If such an object is not initialized in this way, but is nonetheless supplied as an argument to any of sigaction(), sigaddset(), sigdelset(), sigismember(), sigpending() or sigprocmask(), the behavior is undefined.
See also	sigdelset(), sigemptyset(), sigfillset(), sigismember(), signal.h.