sigblock(mask);  int mask; 
 DESCRIPTION
 Sigblock causes the signals specified in
 mask to be added to the set of signals currently
being blocked from delivery. Signal
 i is blocked if the
 i -th bit in 
 mask is a 1.

It is not possible to block SIGKILL,
SIGSTOP, or SIGCONT; this restriction is silently
imposed by the system.
 "RETURN VALUE
The previous set of masked signals is returned.
 "SEE ALSO"
kill(2), sigvec(2), sigsetmask(2),