NAME

sigblock - block signals

LIBRARY

Standard C Library (libc, -lc)

SYNOPSIS



int sigblock(int mask)

int sigmask(signum)

DESCRIPTION

This interface is made obsolete by: sigprocmask(2).

sigblock() adds the signals specified in mask to the set of signals currently being 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.

It is not possible to block SIGKILL or SIGSTOP; this restriction is silently imposed by the system.

RETURN VALUES

The previous set of masked signals is returned.

EXAMPLES

The following example using sigblock():
int omask;
        

omask = sigblock(sigmask(SIGINT) | sigmask(SIGHUP));

Becomes:

sigset_t set, oset;
        

sigemptyset(&set); sigaddset(&set, SIGINT); sigaddset(&set, SIGHUP); sigprocmask(SIG_BLOCK, &set, &oset);

Another use of sigblock() is to get the current set of masked signals without changing what is actually blocked. Instead of:

int set;
        

set = sigblock(0);

Use the following:

sigset_t set;
        

sigprocmask(SIG_BLOCK, NULL, &set);

SEE ALSO

kill(2), sigaction(2), sigprocmask(2), sigsetmask(3), sigsetops(3)

HISTORY

The sigblock() function call appeared in 4.2BSD and has been deprecated.