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.\" @(#)sigprocmask.2 6.4 (Berkeley) 7/23/91 33.\" 34.Dd July 23, 1991 35.Dt SIGPROCMASK 2 36.Os 37.Sh NAME 38.Nm sigprocmask 39.Nd manipulate current signal mask 40.Sh SYNOPSIS 41.Fd #include <signal.h> 42.Ft int 43.Fn sigprocmask "int how" "const sigset_t *set" "sigset_t *oset" 44.Fn sigmask signum 45.Sh DESCRIPTION 46The 47.Fn sigprocmask 48function examines and/or changes the current signal mask (those signals 49that are blocked from delivery). 50Signals are blocked if they are members of the current signal mask set. 51.Pp 52If 53.Fa set 54is not null, the action of 55.Fn sigprocmask 56depends on the value of the parameter 57.Fa how . 58The signal mask is changed as a function of the specified 59.Fa set 60and the current mask. 61The function is specified by 62.Fa how 63using one of the following values from 64.Aq Pa signal.h : 65.Bl -tag -width SIG_UNBLOCK 66.It Dv SIG_BLOCK 67The new mask is the union of the current mask and the specified 68.Fa set . 69.It Dv SIG_UNBLOCK 70The new mask is the intersection of the current mask 71and the complement of the specified 72.Fa set . 73.It Dv SIG_SETMASK 74The current mask is replaced by the specified 75.Fa set . 76.El 77.Pp 78If 79.Fa oset 80is not null, it is set to 81the previous value of the signal mask. 82When 83.Fa set 84is null, 85the value of 86.Ar how 87is insignificant and the mask remains unset 88providing a way to examine the signal mask without modification. 89.Pp 90The system 91quietly disallows 92.Dv SIGKILL 93or 94.Dv SIGSTOP 95to be blocked. 96.Sh RETURN VALUES 97A 0 value indicated that the call succeeded. A -1 return value 98indicates an error occurred and 99.Va errno 100is set to indicated the reason. 101.Sh ERRORS 102The 103.Fn sigprocmask 104call will fail and the signal mask will be unchanged if one 105of the following occurs: 106.Bl -tag -width Bq Er EINVAL 107.It Bq Er EINVAL 108.Fa how 109has a value other than those listed here. 110.Sh SEE ALSO 111.Xr kill 2 , 112.Xr sigaction 2 , 113.Xr sigsetops 3 , 114.Xr sigsuspend 2 115.Sh STANDARDS 116The 117.Nm sigprocmask 118function call is expected to 119conform to 120.St -p1003.1-88 . 121