1.\" $OpenBSD: sigprocmask.2,v 1.9 2011/04/26 23:04:23 schwarze Exp $ 2.\" $NetBSD: sigprocmask.2,v 1.6 1995/02/27 12:37:33 cgd Exp $ 3.\" 4.\" Copyright (c) 1983, 1991, 1993 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" @(#)sigprocmask.2 8.1 (Berkeley) 6/4/93 32.\" 33.Dd $Mdocdate: April 26 2011 $ 34.Dt SIGPROCMASK 2 35.Os 36.Sh NAME 37.Nm sigprocmask 38.Nd manipulate current signal mask 39.Sh SYNOPSIS 40.In signal.h 41.Ft int 42.Fn sigprocmask "int how" "const sigset_t *set" "sigset_t *oset" 43.Sh DESCRIPTION 44The 45.Fn sigprocmask 46function examines and/or changes the current signal mask (those signals 47that are blocked from delivery). 48Signals are blocked if they are members of the current signal mask set. 49.Pp 50If 51.Fa set 52is not null, the action of 53.Fn sigprocmask 54depends on the value of the parameter 55.Fa how , 56which can be one of the following constants defined in 57.In sys/signal.h : 58.Bl -tag -width SIG_UNBLOCK 59.It Dv SIG_BLOCK 60The new mask is the union of the current mask and the specified 61.Fa set . 62.It Dv SIG_UNBLOCK 63The new mask is the intersection of the current mask 64and the complement of the specified 65.Fa set . 66.It Dv SIG_SETMASK 67The current mask is replaced by the specified 68.Fa set . 69.El 70.Pp 71If 72.Fa oset 73is not null, it is set to 74the previous value of the signal mask. 75When 76.Fa set 77is null, 78the value of 79.Ar how 80is insignificant and the mask remains unchanged, 81providing a way to examine the signal mask without modification. 82.Pp 83The system 84quietly disallows 85.Dv SIGKILL 86or 87.Dv SIGSTOP 88to be blocked. 89.Sh RETURN VALUES 90.Rv -std 91.Sh ERRORS 92The 93.Fn sigprocmask 94call will fail and the signal mask will be unchanged if one 95of the following occurs: 96.Bl -tag -width Er 97.It Bq Er EINVAL 98.Fa how 99has a value other than those listed here. 100.El 101.Sh SEE ALSO 102.Xr kill 2 , 103.Xr sigaction 2 , 104.Xr sigsuspend 2 , 105.Xr sigsetops 3 106.Sh STANDARDS 107The 108.Fn sigprocmask 109function call is expected to conform to 110.St -p1003.1-2008 . 111