.\" $NetBSD: sigprocmask.2,v 1.6 1995/02/27 12:37:33 cgd Exp $ .\" .\" Copyright (c) 1983, 1991, 1993 .\" The Regents of the University of California. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. All advertising materials mentioning features or use of this software .\" must display the following acknowledgement: .\" This product includes software developed by the University of .\" California, Berkeley and its contributors. .\" 4. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" @(#)sigprocmask.2 8.1 (Berkeley) 6/4/93 .\" .Dd June 4, 1993 .Dt SIGPROCMASK 2 .Os .Sh NAME .Nm sigprocmask .Nd manipulate current signal mask .Sh SYNOPSIS .Fd #include <signal.h> .Ft int .Fo sigprocmask .Fa "int how" .Fa "const sigset_t *restrict set" .Fa "sigset_t *restrict oset" .Fc .Sh DESCRIPTION The .Fn sigprocmask function examines and/or changes the current signal mask (those signals that are blocked from delivery). Signals are blocked if they are members of the current signal mask set. .Pp If .Fa set is not null, the action of .Fn sigprocmask depends on the value of the parameter .Fa how . The signal mask is changed as a function of the specified .Fa set and the current mask. The function is specified by .Fa how using one of the following values from .Aq Pa signal.h : .Bl -tag -width SIG_UNBLOCK .It Dv SIG_BLOCK The new mask is the union of the current mask and the specified .Fa set . .It Dv SIG_UNBLOCK The new mask is the intersection of the current mask and the complement of the specified .Fa set . .It Dv SIG_SETMASK The current mask is replaced by the specified .Fa set . .El .Pp If .Fa oset is not null, it is set to the previous value of the signal mask. When .Fa set is null, the value of .Ar how is insignificant and the mask remains unset providing a way to examine the signal mask without modification. .Pp The system quietly disallows .Dv SIGKILL or .Dv SIGSTOP to be blocked. .Sh RETURN VALUES A 0 value indicated that the call succeeded. A -1 return value indicates an error occurred and .Va errno is set to indicated the reason. .Sh ERRORS The .Fn sigprocmask call will fail and the signal mask will be unchanged if one of the following occurs: .Bl -tag -width Er .\" =========== .It Bq Er EINVAL .Fa how has a value other than those listed here. .El .Sh SEE ALSO .Xr kill 2 , .Xr sigaction 2 , .Xr sigsuspend 2 , .Xr sigsetops 3 .Sh STANDARDS The .Fn sigprocmask function call is expected to conform to .St -p1003.1-88 .