1.\" $NetBSD: sigprocmask.2,v 1.12 2002/02/08 01:28:22 ross Exp $ 2.\" 3.\" Copyright (c) 1983, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. All advertising materials mentioning features or use of this software 15.\" must display the following acknowledgement: 16.\" This product includes software developed by the University of 17.\" California, Berkeley and its contributors. 18.\" 4. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.\" @(#)sigprocmask.2 8.1 (Berkeley) 6/4/93 35.\" 36.Dd June 4, 1993 37.Dt SIGPROCMASK 2 38.Os 39.Sh NAME 40.Nm sigprocmask 41.Nd manipulate current signal mask 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.Fd #include \*[Lt]signal.h\*[Gt] 46.Ft int 47.Fn sigprocmask "int how" "const sigset_t *set" "sigset_t *oset" 48.Sh DESCRIPTION 49The 50.Fn sigprocmask 51function examines and/or changes the current signal mask (those signals 52that are blocked from delivery). 53Signals are blocked if they are members of the current signal mask set. 54.Pp 55If 56.Fa set 57is not null, the action of 58.Fn sigprocmask 59depends on the value of the parameter 60.Fa how . 61The signal mask is changed as a function of the specified 62.Fa set 63and the current mask. 64The function is specified by 65.Fa how 66using one of the following values from 67.Aq Pa signal.h : 68.Bl -tag -width SIG_UNBLOCK 69.It Dv SIG_BLOCK 70The new mask is the union of the current mask and the specified 71.Fa set . 72.It Dv SIG_UNBLOCK 73The new mask is the intersection of the current mask 74and the complement of the specified 75.Fa set . 76.It Dv SIG_SETMASK 77The current mask is replaced by the specified 78.Fa set . 79.El 80.Pp 81If 82.Fa oset 83is not null, it is set to 84the previous value of the signal mask. 85When 86.Fa set 87is null, 88the value of 89.Ar how 90is insignificant and the mask remains unset 91providing a way to examine the signal mask without modification. 92.Pp 93The system 94quietly disallows 95.Dv SIGKILL 96or 97.Dv SIGSTOP 98to be blocked. 99.Sh RETURN VALUES 100A 0 value indicates that the call succeeded. A -1 return value 101indicates an error occurred and 102.Va errno 103is set to indicate the reason. 104.Sh ERRORS 105The 106.Fn sigprocmask 107call will fail and the signal mask will be unchanged if one 108of the following occurs: 109.Bl -tag -width Er 110.It Bq Er EINVAL 111.Fa how 112has a value other than those listed here. 113.El 114.Sh SEE ALSO 115.Xr kill 2 , 116.Xr sigaction 2 , 117.Xr sigsuspend 2 , 118.Xr sigsetops 3 , 119.Xr signal 7 120.Sh STANDARDS 121The 122.Fn sigprocmask 123function conforms to 124.St -p1003.1-90 . 125