@node sigaddset, signal
@subheading Syntax

@example
#include <signal.h>

int sigaddset (sigset_t *set, int signo)
@end example

@subheading Description

This function adds the individual signal specified by @var{signo} the
set of signals pointed to by @var{set}.

@subheading Return Value

0 upon success, -1 if @var{set} is a NULL pointer, or if @var{signo} is
specifies an unknown signal.

@subheading Portability

@portability !ansi, posix