1.\" $NetBSD: sigprocmask.2,v 1.22 2006/01/07 20:11:30 kleink 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. Neither the name of the University nor the names of its contributors 15.\" may be used to endorse or promote products derived from this software 16.\" without specific prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.\" @(#)sigprocmask.2 8.1 (Berkeley) 6/4/93 31.\" 32.Dd June 4, 1993 33.Dt SIGPROCMASK 2 34.Os 35.Sh NAME 36.Nm sigprocmask 37.Nd manipulate current signal mask 38.Sh LIBRARY 39.Lb libc 40.Sh SYNOPSIS 41.In signal.h 42.Ft int 43.Fn sigprocmask "int how" "const sigset_t * restrict set" "sigset_t * restrict oset" 44.Sh DESCRIPTION 45The 46.Fn sigprocmask 47function examines and/or changes the current signal mask (those signals 48that are blocked from delivery). 49Signals are blocked if they are members of the current signal mask set. 50.Pp 51If 52.Fa set 53is not null, the action of 54.Fn sigprocmask 55depends on the value of the parameter 56.Fa how . 57The signal mask is changed as a function of the specified 58.Fa set 59and the current mask. 60The function is specified by 61.Fa how 62using one of the following values: 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. 80.Pp 81When 82.Fa set 83is null, 84the value of 85.Ar how 86is insignificant and the mask remains unset 87providing a way to examine the signal mask without modification. 88.Pp 89The system 90quietly disallows 91.Dv SIGKILL 92or 93.Dv SIGSTOP 94to be blocked. 95.Sh RETURN VALUES 96A 0 value indicates that the call succeeded. 97A \-1 return value indicates an error occurred and 98.Va errno 99is set to indicate the reason. 100.Sh ERRORS 101The 102.Fn sigprocmask 103call will fail and the signal mask will be unchanged if one 104of the following occurs: 105.Bl -tag -width Er 106.It Bq Er EINVAL 107.Fa how 108has a value other than those listed here. 109.El 110.Sh SEE ALSO 111.Xr kill 2 , 112.Xr sigaction 2 , 113.Xr sigsuspend 2 , 114.Xr pthread_sigmask 3 , 115.Xr sigsetops 3 , 116.Xr signal 7 117.Sh STANDARDS 118The 119.Fn sigprocmask 120function conforms to 121.St -p1003.1-90 . 122