SIGBLOCK(3)						   BSD Library Functions Manual 					       SIGBLOCK(3)

NAME

     sigblock -- block signals

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <signal.h>

     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 corre-
     sponding 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.

BSD
								  August 10, 2002							       BSD