sigsetops(3) — Linux manual page


SIGSETOPS(3)            Library Functions Manual            SIGSETOPS(3)

NAME         top

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

LIBRARY         top

       Standard C library (libc, -lc)

SYNOPSIS         top

       #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

       sigemptyset(), sigfillset(), sigaddset(), sigdelset(),

DESCRIPTION         top

       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         top

       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 error.

ERRORS         top

       EINVAL signum is not a valid signal.

ATTRIBUTES         top

       For an explanation of the terms used in this section, see
       │ Interface                           Attribute     Value   │
       │ sigemptyset(), sigfillset(),        │ Thread safety │ MT-Safe │
       │ sigaddset(), sigdelset(),           │               │         │
       │ sigismember(), sigisemptyset(),     │               │         │
       │ sigorset(), sigandset()             │               │         │

VERSIONS         top

       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

       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

STANDARDS         top


HISTORY         top


NOTES         top

       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

SEE ALSO         top

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

COLOPHON         top

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Linux man-pages 6.9.1          2024-05-02                   SIGSETOPS(3)

Pages that refer to this page: sigaction(2)signal(2)signalfd(2)sigpending(2)sigprocmask(2)sigsuspend(2)sigwaitinfo(2)pthread_attr_setsigmask_np(3)pthread_sigmask(3)sigwait(3)nptl(7)signal(7)signal-safety(7)