#include <signal.h> 
 sigsetmask(mask);  int mask; 
 mask = sigmask(signum) 
 DESCRIPTION
 "This interface is made obsolete by sigprocmask(2). 

 Sigsetmask sets the current signal mask (those signals
that are blocked from delivery).
Signals are blocked if the
corresponding bit in 
 mask is a 1; the macro
 sigmask is provided to construct the mask for a given
 signum . 

The system
quietly disallows SIGKILL or SIGSTOP to be blocked.
 "RETURN VALUE
The previous set of masked signals is returned.
 "SEE ALSO"
sigprocmask(2), kill(2), sigaction(2), sigsuspend(2),
sigvec(2), sigblock(2), sigsetops(3)