1.\" Copyright (c) 1983, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.Dd August 16, 2013 29.Dt SIGSUSPEND 2 30.Os 31.Sh NAME 32.Nm sigsuspend 33.Nd atomically release blocked signals and wait for interrupt 34.Sh LIBRARY 35.Lb libc 36.Sh SYNOPSIS 37.In signal.h 38.Ft int 39.Fn sigsuspend "const sigset_t *sigmask" 40.Sh DESCRIPTION 41The 42.Fn sigsuspend 43system call 44temporarily changes the blocked signal mask to the set to which 45.Fa sigmask 46points, 47and then waits for a signal to arrive; 48on return the previous set of masked signals is restored. 49The signal mask set 50is usually empty to indicate that all 51signals are to be unblocked for the duration of the call. 52.Pp 53In normal usage, a signal is blocked using 54.Xr sigprocmask 2 55to begin a critical section, variables modified on the occurrence 56of the signal are examined to determine that there is no work 57to be done, and the process pauses awaiting work by using 58.Fn sigsuspend 59with the previous mask returned by 60.Xr sigprocmask 2 . 61.Sh RETURN VALUES 62The 63.Fn sigsuspend 64system call 65always terminates by being interrupted, returning -1 with 66.Va errno 67set to 68.Er EINTR . 69.Sh SEE ALSO 70.Xr pselect 2 , 71.Xr sigaction 2 , 72.Xr sigpending 2 , 73.Xr sigprocmask 2 , 74.Xr sigtimedwait 2 , 75.Xr sigwait 2 , 76.Xr sigwaitinfo 2 , 77.Xr sigsetops 3 78.Sh STANDARDS 79The 80.Fn sigsuspend 81system call is expected to conform to 82.St -p1003.1-90 . 83