sigwait(3)

NAME#

sigwait - wait for a signal

LIBRARY#

Standard C library (libc, -lc)

SYNOPSIS#

#include <signal.h>

int sigwait(const sigset_t *restrict \nset\n, int *restrict \nsig\n);

sigwait():

\n
    Since glibc 2.26:
\n
        _POSIX_C_SOURCE >= 199506L
\n
    glibc 2.25 and earlier:
\n
        _POSIX_C_SOURCE

DESCRIPTION#

The sigwait() function suspends execution of the calling thread until one of the signals specified in the signal set set becomes pending. For a signal to become pending, it must first be blocked with sigprocmask(2). The function accepts the signal (removes it from the pending list of signals), and returns the signal number in sig.

The operation of sigwait() is the same as sigwaitinfo(2), except that:

•

sigwait() returns only the signal number, rather than a siginfo_t structure describing the signal.

•

The return values of the two functions are different.

RETURN VALUE#

On success, sigwait() returns 0. On error, it returns a positive error number (listed in ERRORS).

ERRORS#

EINVAL

set contains an invalid signal number.

ATTRIBUTES#

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

VERSIONS#

sigwait() is implemented using sigtimedwait(2); consult its NOTES.

The glibc implementation of sigwait() silently ignores attempts to wait for the two real-time signals that are used internally by the NPTL threading implementation. See nptl(7) for details.

STANDARDS#

POSIX.1-2008.

HISTORY#

POSIX.1-2001.

EXAMPLES#

See pthread_sigmask(3).

SEE ALSO#

sigaction(2), signalfd(2), sigpending(2), sigsuspend(2), sigwaitinfo(2), sigsetops(3), signal(7)