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.Dd May 7, 2010 29.Dt SIGPROCMASK 2 30.Os 31.Sh NAME 32.Nm sigprocmask 33.Nd manipulate current signal mask 34.Sh LIBRARY 35.Lb libc 36.Sh SYNOPSIS 37.In signal.h 38.Ft int 39.Fo sigprocmask 40.Fa "int how" 41.Fa "const sigset_t * restrict set" 42.Fa "sigset_t * restrict oset" 43.Fc 44.Sh DESCRIPTION 45The 46.Fn sigprocmask 47system call 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 56.Fa how 57argument. 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.In 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.Fa 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.Pp 97In threaded applications, 98.Xr pthread_sigmask 3 99must be used instead of 100.Fn sigprocmask . 101.Sh RETURN VALUES 102.Rv -std sigprocmask 103.Sh ERRORS 104The 105.Fn sigprocmask 106system call will fail and the signal mask will be unchanged if one 107of the following occurs: 108.Bl -tag -width Er 109.It Bq Er EINVAL 110The 111.Fa how 112argument 113has a value other than those listed here. 114.El 115.Sh SEE ALSO 116.Xr kill 2 , 117.Xr sigaction 2 , 118.Xr sigpending 2 , 119.Xr sigsuspend 2 , 120.Xr fpsetmask 3 , 121.Xr pthread_sigmask 3 , 122.Xr sigsetops 3 123.Sh STANDARDS 124The 125.Fn sigprocmask 126system call is expected to 127conform to 128.St -p1003.1-90 . 129