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     SIGSET(S)                 UNIX System V                 SIGSET(S)



     Name
          sigset - manipulate signal sets

     Syntax
          #include <signal.h>

          int sigemptyset (set)
          sigset_t *set;

          int sigfillset (set)
          sigset_t *set;

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

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

          int sigismember (set)
          sigset_t *set
          int signo;

     Description
          The sigsetops primitives manipulate sets of signals.  The
          operate on data objects addressable by the application, not
          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).)

          The sigemptyset() function initializes the signal set
          pointed to by the argument set, such that all signals are
          excluded.

          The sigfillset() function initializes the signal set pointed
          to by the argument set, such that all signals are included.

          Applications call either sigemptyset() or sigfullset() at
          least once for each object of type sigset_t prior to any use
          of that object.  If such an object is not initialized in
          this way, but is nonetheless supplied as an argument to any
          of the sigaddset(), sigdelset(), sigismember(), sigaction(),
          sigprocmask(), sigpending(), or sigsuspend() functions, the
          result is undefined.

          The sigaddset() and sigdelset() functions respectively add
          and delete the individual signal specified by the value of
          the argument signo from the signal set pointed to by the
          argument set.

          The sigismember() function tests whether the signal
          specified by the value of the argument signo is a member of
          the set pointed to by the argument set .

     Return Value
          Upon successful completion, the sigismember() function
          retains 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 above functions, if an error is
          detected, a value of -1 is returned and errno is set to
          indicate the error.

     See Also
          sigaction(S), signal(S)

     Diagnostics
          For each of the following conditions, if the condition is
          detected, 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.

     Standards Conformance
          sigset is conformant with:
          AT&T SVID Issue 2, Select Code 307-127.

                                             (printed 6/20/89)