freebsd man page for sigaddset

SIGSETOPS(3)						   BSD Library Functions Manual 					      SIGSETOPS(3)

NAME
     sigemptyset, sigfillset, sigaddset, sigdelset, sigismember -- manipulate signal sets

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <signal.h>

     int
     sigemptyset(sigset_t *set);

     int
     sigfillset(sigset_t *set);

     int
     sigaddset(sigset_t *set, int signo);

     int
     sigdelset(sigset_t *set, int signo);

     int
     sigismember(const sigset_t *set, int signo);

DESCRIPTION
     These functions manipulate signal sets stored in a sigset_t.  Either sigemptyset() or sigfillset() must be called for every object of type
     sigset_t before any other use of the object.

     The sigemptyset() function initializes a signal set to be empty.

     The sigfillset() function initializes a signal set to contain all signals.

     The sigaddset() function adds the specified signal signo to the signal set.

     The sigdelset() function deletes the specified signal signo from the signal set.

     The sigismember() function returns whether a specified signal signo is contained in the signal set.

RETURN VALUES
     The sigismember() function returns 1 if the signal is a member of the set, 0 otherwise.  The other functions return 0 upon success.  A -1
     return value indicates an error occurred and the global variable errno is set to indicate the reason.

ERRORS
     These functions could fail if one of the following occurs:

     [EINVAL]		signo has an invalid value.

SEE ALSO
     kill(2), sigaction(2), sigpending(2), sigprocmask(2), sigsuspend(2)

STANDARDS
     These functions are defined by IEEE Std 1003.1-1988 (``POSIX.1'').

BSD
								 December 16, 2004							       BSD