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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | STANDARDS | HISTORY | NOTES | EXAMPLES | SEE ALSO | COLOPHON |
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pthread_sigmask(3) Library Functions Manual pthread_sigmask(3)
pthread_sigmask - examine and change mask of blocked signals
POSIX threads library (libpthread, -lpthread)
#include <signal.h>
int pthread_sigmask(int how, const sigset_t *set, sigset_t *oldset);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
pthread_sigmask():
_POSIX_C_SOURCE >= 199506L || _XOPEN_SOURCE >= 500
The pthread_sigmask() function is just like sigprocmask(2), with
the difference that its use in multithreaded programs is
explicitly specified by POSIX.1. Other differences are noted in
this page.
For a description of the arguments and operation of this function,
see sigprocmask(2).
On success, pthread_sigmask() returns 0; on error, it returns an
error number.
See sigprocmask(2).
For an explanation of the terms used in this section, see
attributes(7).
┌──────────────────────────────────────┬───────────────┬─────────┐
│ Interface │ Attribute │ Value │
├──────────────────────────────────────┼───────────────┼─────────┤
│ pthread_sigmask() │ Thread safety │ MT-Safe │
└──────────────────────────────────────┴───────────────┴─────────┘
POSIX.1-2008.
POSIX.1-2001.
A new thread inherits a copy of its creator's signal mask.
The glibc pthread_sigmask() function silently ignores attempts to
block the two real-time signals that are used internally by the
NPTL threading implementation. See nptl(7) for details.
The program below blocks some signals in the main thread, and then
creates a dedicated thread to fetch those signals via sigwait(3).
The following shell session demonstrates its use:
$ ./a.out &
[1] 5423
$ kill -QUIT %1
Signal handling thread got signal 3
$ kill -USR1 %1
Signal handling thread got signal 10
$ kill -TERM %1
[1]+ Terminated ./a.out
Program source
#include <errno.h>
#include <pthread.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
/* Simple error handling functions */
#define handle_error_en(en, msg) \
do { errno = en; perror(msg); exit(EXIT_FAILURE); } while (0)
static void *
sig_thread(void *arg)
{
sigset_t *set = arg;
int s, sig;
for (;;) {
s = sigwait(set, &sig);
if (s != 0)
handle_error_en(s, "sigwait");
printf("Signal handling thread got signal %d\n", sig);
}
}
int
main(void)
{
pthread_t thread;
sigset_t set;
int s;
/* Block SIGQUIT and SIGUSR1; other threads created by main()
will inherit a copy of the signal mask. */
sigemptyset(&set);
sigaddset(&set, SIGQUIT);
sigaddset(&set, SIGUSR1);
s = pthread_sigmask(SIG_BLOCK, &set, NULL);
if (s != 0)
handle_error_en(s, "pthread_sigmask");
s = pthread_create(&thread, NULL, &sig_thread, &set);
if (s != 0)
handle_error_en(s, "pthread_create");
/* Main thread carries on to create other threads and/or do
other work. */
pause(); /* Dummy pause so we can test program */
}
sigaction(2), sigpending(2), sigprocmask(2),
pthread_attr_setsigmask_np(3), pthread_create(3), pthread_kill(3),
sigsetops(3), pthreads(7), signal(7)
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 pthread_sigmask(3)
Pages that refer to this page: sigprocmask(2), pthread_attr_setsigmask_np(3), pthread_create(3), pthread_kill(3), pthread_sigqueue(3), sd_event_add_child(3), sd_event_add_signal(3), sigset(3), sigwait(3), nptl(7), pthreads(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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