sigblock(2)
NAME
sigblock − block signals
SYNTAX
sigblock(mask);
int mask;
DESCRIPTION
The sigblock system call 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.
The previous set of masked signals is returned.