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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | VERSIONS | STANDARDS | HISTORY | NOTES | SEE ALSO | COLOPHON |
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SIGSETOPS(3) Library Functions Manual SIGSETOPS(3)
sigemptyset, sigfillset, sigaddset, sigdelset, sigismember - POSIX
signal set operations
Standard C library (libc, -lc)
#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
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.
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.
EINVAL signum is not a valid signal.
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() │ │ │
└──────────────────────────────────────┴───────────────┴─────────┘
GNU
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.
POSIX.1-2008.
POSIX.1-2001.
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.
sigaction(2), sigpending(2), sigprocmask(2), sigsuspend(2)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.15.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2025-08-11. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
man-pages@man7.org
Linux man-pages 6.15 2025-05-17 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)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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