sigset(S)                      6 January 1993                      sigset(S)


 Name

    sigset - manipulate signal sets

 Syntax


    cc  . . .  -lc


    #include  <signal.h>

    int sigemptyset (set)
    sigset_t *set;

    int sigfillset (set)
    sigset_t *set;

    int sigaddset (set, signo)
    sigset_t *set;
    int signo;

    int sigdelset (set, signo)
    sigset_t *set;
    int signo;

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


 Description

    These functions manipulate sets of signals.  They operate on data objects
    addressable by the application. They do not operate on any set of signals
    known to the system, such as the set blocked from delivery to a process
    or the set pending for a process (see signal(S) or sigaction(S).)

    The sigemptyset routine initializes the signal set to which the argument
    set points, so that all signals are excluded.

    The sigfillset routine initializes the signal set to which the argument
    set points, so that all signals are included.

    Applications should call either the sigemptyset or the sigfillset rou-
    tines at least once for each object of type sigsett before using that
    object.  If an object of type sigsett is not initialized as described
    but is used as an argument in any sigaddset, sigdelset, sigismember,
    sigaction, signal, sigprocmask, sigpending, or sigsuspend routine, its
    behavior is undefined.

    The sigaddset adds and sigdelset deletes the individual signal specified
    by the argument signo from the signal set to which the argument set
    points.

    The sigismember function tests whether the signal specified by the argu-
    ment signo is a member of the signal set to which the argument set
    points.

 Return value

    Upon successful completion, the sigismember function returns a value of
    one if the specified signal is a member of the specified set, or a value
    of zero if it is not.  Upon successful completion, the other functions
    return a value of zero.  For all of the functions, if an error is
    detected, a value of -1 is returned and errno is set to indicate the
    error.

 Diagnostics

    For the following condition, the sigaddset, sigdelset, and sigismember
    functions return a -1 and set errno to the corresponding value:


    [EINVAL]  The value of the signal argument is an invalid or unsupported
              signal number.


 See also

    sigaction(S), signal(S), sigpending(S), sigprocmask(S), sigsuspend(S),
    sigsetjmp(S) sigsetv(S),

 Standards conformance

    sigset conforms with:
    AT&T SVID Issue 2; and
    X/Open Portability Guide, Issue 3, 1989.