NAME    [Toc]    [Back]

       sigemptyset, sigfillset, sigaddset, sigdelset, sigismember
       - Create and manipulates signal masks

SYNOPSIS    [Toc]    [Back]

       #include <signal.h>

       int sigemptyset(
               sigset_t *set ); int sigfillset(
               sigset_t *set ); int sigaddset(
               sigset_t *set,
               int sig_number ); int sigdelset(
               sigset_t *set,
               int sig_number ); int sigismember(
               sigset_t *set,
               int sig_number );

LIBRARY    [Toc]    [Back]

       Standard C Library (libc)

STANDARDS    [Toc]    [Back]

       Interfaces documented on this reference  page  conform  to
       industry standards as follows:

       sigemptyset(),   sigfillset(),   sigaddset(),  sigdelset()
       sigismember():  XPG4, XPG4-UNIX

       Refer to the standards(5) reference page for more information
 about industry standards and associated tags.

PARAMETERS    [Toc]    [Back]

       Specifies  the  signal set.  Specifies the individual signal.

DESCRIPTION    [Toc]    [Back]

       The sigemptyset(),sigfillset(),sigaddset()sigdelset()  and
       sigismember()  functions manipulate sets of signals. These
       functions operate on data objects that can be addressed 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.

       The  sigemptyset()  function  initializes  the  signal set
       pointed to by the set parameter such that all signals  are
       excluded. The sigfillset() function initializes the signal
       set pointed to by the set parameter such that all  signals
       are included. A call to either the sigfillset() or sigemptyset()
 function must be  made  at  least  once  for  each
       object of the type sigset_t prior to any other use of that
       object.

       The sigaddset() and sigdelset() functions respectively add
       and delete the individual signal specified by the sig_number
 parameter from the signal set  specified  by  the  set
       parameter.  The  sigismember()  function tests whether the
       sig_number parameter is a member of the signal set pointed
       to by the set parameter.

RETURN VALUES    [Toc]    [Back]

       Upon  successful  completion,  the  sigismember() function
       returns a value of 1 if the specified signal is  a  member
       of the specified set, or a value of 0 (zero) if it is not.
       Upon successful completion, the other functions  return  a
       value  of  0. For all the preceding functions, if an error
       is detected, a value of -1 is returned and errno is set to
       indicate the error.

ERRORS    [Toc]    [Back]

       The    sigfillset(),   sigdelset(),   sigismember(),   and
       sigaddset() functions set errno to  the  specified  values
       for  the following conditions: The value of the sig_number
       parameter is not a valid signal number.

EXAMPLES    [Toc]    [Back]

       To generate and use a signal mask  that  blocks  only  the
       SIGINT signal from delivery, enter:

       #include <signal.h> int return_value; sigset_t newset;
          .  .  .   sigemptyset(&newset); sigaddset(&newset, SIGINT);
 return_value =  sigprocmask  (SIG_SETMASK,  &newset,
       NULL);

SEE ALSO    [Toc]    [Back]

       Functions:  sigaction(2),  sigprocmask(2),  sigsuspend(2),
       sigvec(2)

       Files: signal(4)

       Standards: standards(5)



                                                   sigemptyset(3)