1.\" Copyright (c) 1983, 1991, 1993 2.\" The Regents of the University of California. 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. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)sigprocmask.2 8.1 (Berkeley) 6/4/93 29.\" $FreeBSD: src/lib/libc/sys/sigprocmask.2,v 1.8.2.5 2001/12/14 18:34:01 ru Exp $ 30.\" $DragonFly: src/lib/libc/sys/sigprocmask.2,v 1.4 2007/09/08 20:50:50 swildner Exp $ 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 *set" "sigset_t *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 from 63.In signal.h : 64.Bl -tag -width ".Dv SIG_UNBLOCK" 65.It Dv SIG_BLOCK 66The new mask is the union of the current mask and the specified 67.Fa set . 68.It Dv SIG_UNBLOCK 69The new mask is the intersection of the current mask 70and the complement of the specified 71.Fa set . 72.It Dv SIG_SETMASK 73The current mask is replaced by the specified 74.Fa set . 75.El 76.Pp 77If 78.Fa oset 79is not null, it is set to 80the previous value of the signal mask. 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 96.Rv -std sigprocmask 97.Sh ERRORS 98The 99.Fn sigprocmask 100call will fail and the signal mask will be unchanged if one 101of the following occurs: 102.Bl -tag -width Er 103.It Bq Er EINVAL 104.Fa how 105has a value other than those listed here. 106.El 107.Sh SEE ALSO 108.Xr kill 2 , 109.Xr sigaction 2 , 110.Xr sigsuspend 2 , 111.Xr fpsetmask 3 , 112.Xr sigsetops 3 113.Sh STANDARDS 114The 115.Fn sigprocmask 116function call is expected to 117conform to 118.St -p1003.1-90 . 119