sigblock, siggetmask, sigsetmask, sigmask - manipulate the
int sigblock(int mask));
int sigsetmask(int mask));
int sigmask(int signum));
This interface is made obsolete by sigprocmask(2).
The sigblock system call adds the signals specified in mask
to the set of signals currently being blocked from delivery.
The sigsetmask system call replaces the set of blocked sig-
nals totally with a new set specified in mask. Signals are
blocked if the corresponding bit in mask is a 1.
The current set of blocked signals can be obtained using
The sigmask macro is provided to construct the mask for a
siggetmask returns the current set of masked signals.
sigsetmask and sigblock return the previous set of masked
Prototypes for these functions are only available if
__USE_BSD is defined before <signal.h> is included.
It is not possible to block SIGKILL or SIGSTOP - this res-
triction is silently imposed by the system.
4.4BSD. These function calls appeared in BSD 4.3 and are
deprecated. Use the POSIX signal facilities for new pro-
kill(2), sigprocmask(2), signal(7)