1.\" $OpenBSD: sigprocmask.2,v 1.8 2007/05/31 19:19:34 jmc 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: May 31 2007 $ 34.Dt SIGPROCMASK 2 35.Os 36.Sh NAME 37.Nm sigprocmask 38.Nd manipulate current signal mask 39.Sh SYNOPSIS 40.Fd #include <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 . 56The signal mask is changed as a function of the specified 57.Fa set 58and the current mask. 59The function is specified by 60.Fa how 61using one of the following values from 62.Aq Pa sys/signal.h : 63.Bl -tag -width SIG_UNBLOCK 64.It Dv SIG_BLOCK 65The new mask is the union of the current mask and the specified 66.Fa set . 67.It Dv SIG_UNBLOCK 68The new mask is the intersection of the current mask 69and the complement of the specified 70.Fa set . 71.It Dv SIG_SETMASK 72The current mask is replaced by the specified 73.Fa set . 74.El 75.Pp 76If 77.Fa oset 78is not null, it is set to 79the previous value of the signal mask. 80When 81.Fa set 82is null, 83the value of 84.Ar how 85is insignificant and the mask remains unset 86providing a way to examine the signal mask without modification. 87.Pp 88The system 89quietly disallows 90.Dv SIGKILL 91or 92.Dv SIGSTOP 93to be blocked. 94.Sh RETURN VALUES 95A 0 value indicated that the call succeeded. 96A \-1 return value indicates an error occurred and 97.Va errno 98is set to indicated the reason. 99.Sh ERRORS 100The 101.Fn sigprocmask 102call will fail and the signal mask will be unchanged if one 103of the following occurs: 104.Bl -tag -width Er 105.It Bq Er EINVAL 106.Fa how 107has a value other than those listed here. 108.El 109.Sh SEE ALSO 110.Xr kill 2 , 111.Xr sigaction 2 , 112.Xr sigsuspend 2 , 113.Xr sigsetops 3 114.Sh STANDARDS 115The 116.Fn sigprocmask 117function call is expected to conform to 118.St -p1003.1-88 . 119