1.\" Copyright (c) 1983, 1991 The Regents of the University of California. 2.\" 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. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" from: @(#)sigprocmask.2 6.4 (Berkeley) 7/23/91 33.\" $Id: sigprocmask.2,v 1.4 1993/11/29 21:25:39 jtc Exp $ 34.\" 35.Dd July 23, 1991 36.Dt SIGPROCMASK 2 37.Os 38.Sh NAME 39.Nm sigprocmask 40.Nd manipulate current signal mask 41.Sh SYNOPSIS 42.Fd #include <signal.h> 43.Ft int 44.Fn sigprocmask "int how" "const sigset_t *set" "sigset_t *oset" 45.Fn sigmask signum 46.Sh DESCRIPTION 47The 48.Fn sigprocmask 49function examines and/or changes the current signal mask (those signals 50that are blocked from delivery). 51Signals are blocked if they are members of the current signal mask set. 52.Pp 53If 54.Fa set 55is not null, the action of 56.Fn sigprocmask 57depends on the value of the parameter 58.Fa how . 59The signal mask is changed as a function of the specified 60.Fa set 61and the current mask. 62The function is specified by 63.Fa how 64using one of the following values from 65.Aq Pa signal.h : 66.Bl -tag -width SIG_UNBLOCK 67.It Dv SIG_BLOCK 68The new mask is the union of the current mask and the specified 69.Fa set . 70.It Dv SIG_UNBLOCK 71The new mask is the intersection of the current mask 72and the complement of the specified 73.Fa set . 74.It Dv SIG_SETMASK 75The current mask is replaced by the specified 76.Fa set . 77.El 78.Pp 79If 80.Fa oset 81is not null, it is set to 82the previous value of the signal mask. 83When 84.Fa set 85is null, 86the value of 87.Ar how 88is insignificant and the mask remains unset 89providing a way to examine the signal mask without modification. 90.Pp 91The system 92quietly disallows 93.Dv SIGKILL 94or 95.Dv SIGSTOP 96to be blocked. 97.Sh RETURN VALUES 98A 0 value indicated that the call succeeded. A -1 return value 99indicates an error occurred and 100.Va errno 101is set to indicated the reason. 102.Sh ERRORS 103The 104.Fn sigprocmask 105call will fail and the signal mask will be unchanged if one 106of the following occurs: 107.Bl -tag -width Er 108.It Bq Er EINVAL 109.Fa how 110has a value other than those listed here. 111.El 112.Sh SEE ALSO 113.Xr kill 2 , 114.Xr sigaction 2 , 115.Xr sigsetops 3 , 116.Xr sigsuspend 2 117.Sh STANDARDS 118The 119.Fn sigprocmask 120function call is expected to 121conform to 122.St -p1003.1-88 . 123