'\" t .\" Copyright (c) 2008, Linux Foundation, written by Michael Kerrisk .\" .\" .\" SPDX-License-Identifier: Linux-man-pages-copyleft .\" .TH sigwait 3 2024-05-02 "Linux man-pages 6.9.1" .SH NAME sigwait \- wait for a signal .SH LIBRARY Standard C library .RI ( libc ", " \-lc ) .SH SYNOPSIS .nf .B #include .P .BI "int sigwait(const sigset_t *restrict " set ", int *restrict " sig ); .fi .P .RS -4 Feature Test Macro Requirements for glibc (see .BR feature_test_macros (7)): .RE .P .BR sigwait (): .nf Since glibc 2.26: _POSIX_C_SOURCE >= 199506L glibc 2.25 and earlier: _POSIX_C_SOURCE .fi .SH DESCRIPTION The .BR sigwait () function suspends execution of the calling thread until one of the signals specified in the signal set .I set becomes pending. For a signal to become pending, it must first be blocked with .BR sigprocmask (2). The function accepts the signal (removes it from the pending list of signals), and returns the signal number in .IR sig . .P The operation of .BR sigwait () is the same as .BR sigwaitinfo (2), except that: .IP \[bu] 3 .BR sigwait () returns only the signal number, rather than a .I siginfo_t structure describing the signal. .IP \[bu] The return values of the two functions are different. .SH RETURN VALUE On success, .BR sigwait () returns 0. On error, it returns a positive error number (listed in ERRORS). .SH ERRORS .TP .B EINVAL .\" Does not occur for glibc. .I set contains an invalid signal number. .SH ATTRIBUTES For an explanation of the terms used in this section, see .BR attributes (7). .TS allbox; lbx lb lb l l l. Interface Attribute Value T{ .na .nh .BR sigwait () T} Thread safety MT-Safe .TE .SH VERSIONS .BR sigwait () is implemented using .BR sigtimedwait (2); consult its .BR NOTES . .P The glibc implementation of .BR sigwait () silently ignores attempts to wait for the two real-time signals that are used internally by the NPTL threading implementation. See .BR nptl (7) for details. .SH STANDARDS POSIX.1-2008. .SH HISTORY POSIX.1-2001. .SH EXAMPLES See .BR pthread_sigmask (3). .SH SEE ALSO .BR sigaction (2), .BR signalfd (2), .BR sigpending (2), .BR sigsuspend (2), .BR sigwaitinfo (2), .BR sigsetops (3), .BR signal (7)