NAME

       sigemptyset, sigfillset, sigaddset, sigdelset, sigismember - POSIX signal set operations

SYNOPSIS

       #include <signal.h>

       int sigemptyset(sigset_t *set);

       int sigfillset(sigset_t *set);

       int sigaddset(sigset_t *set, int signum);

       int sigdelset(sigset_t *set, int signum);

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

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       sigemptyset(), sigfillset(), sigaddset(), sigdelset(), sigismember():
           _POSIX_C_SOURCE >= 1 || _XOPEN_SOURCE || _POSIX_SOURCE

DESCRIPTION

       These functions allow the manipulation of POSIX signal sets.

       sigemptyset() initializes the signal set given by set to empty, with all signals excluded from the set.

       sigfillset() initializes set to full, including all signals.

       sigaddset() and sigdelset() add and delete respectively signal signum from set.

       sigismember() tests whether signum is a member of set.

       Objects  of  type  sigset_t  must be initialized by a call to either sigemptyset() or sigfillset() before
       being passed to the  functions  sigaddset(),  sigdelset()  and  sigismember()  or  the  additional  glibc
       functions  described  below (sigisemptyset(), sigandset(), and sigorset()).  The results are undefined if
       this is not done.

RETURN VALUE

       sigemptyset(), sigfillset(), sigaddset(), and sigdelset() return 0 on success and -1 on error.

       sigismember() returns 1 if signum is a member of set, 0 if signum is not a member, and -1 on error.

       On error, these functions set errno to indicate the cause of the error.

ERRORS

       EINVAL sig is not a valid signal.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       ┌────────────────────────────────┬───────────────┬─────────┐
       │Interface                       │ Attribute     │ Value   │
       ├────────────────────────────────┼───────────────┼─────────┤
       │sigemptyset(), sigfillset(),    │ Thread safety │ MT-Safe │
       │sigaddset(), sigdelset(),       │               │         │
       │sigismember(), sigisemptyset(), │               │         │
       │sigorset(), sigandset()         │               │         │
       └────────────────────────────────┴───────────────┴─────────┘

CONFORMING TO

       POSIX.1-2001, POSIX.1-2008.

NOTES

       When creating a filled signal set, the glibc sigfillset() function does not  include  the  two  real-time
       signals used internally by the NPTL threading implementation.  See nptl(7) for details.

   Glibc extensions
       If  the  _GNU_SOURCE  feature  test  macro  is defined, then <signal.h> exposes three other functions for
       manipulating signal sets:

       int sigisemptyset(const sigset_t *set);
       int sigorset(sigset_t *dest, const sigset_t *left,
                     const sigset_t *right);
       int sigandset(sigset_t *dest, const sigset_t *left,
                     const sigset_t *right);

       sigisemptyset() returns 1 if set contains no signals, and 0 otherwise.

       sigorset() places the union of the sets left and right in dest.  sigandset() places the  intersection  of
       the sets left and right in dest.  Both functions return 0 on success, and -1 on failure.

       These  functions  are nonstandard (a few other systems provide similar functions) and their use should be
       avoided in portable applications.

SEE ALSO

       sigaction(2), sigpending(2), sigprocmask(2), sigsuspend(2)

COLOPHON

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