1.\" $OpenBSD: umask.2,v 1.8 2007/05/31 19:19:34 jmc Exp $ 2.\" $NetBSD: umask.2,v 1.6 1995/02/27 12:39:06 cgd Exp $ 3.\" 4.\" Copyright (c) 1980, 1991, 1993 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" @(#)umask.2 8.1 (Berkeley) 6/4/93 32.\" 33.Dd $Mdocdate: May 31 2007 $ 34.Dt UMASK 2 35.Os 36.Sh NAME 37.Nm umask 38.Nd set file creation mode mask 39.Sh SYNOPSIS 40.Fd #include <sys/types.h> 41.Fd #include <sys/stat.h> 42.Ft mode_t 43.Fn umask "mode_t numask" 44.Sh DESCRIPTION 45The 46.Fn umask 47routine sets the process's file mode creation mask to 48.Fa numask 49and returns the previous value of the mask. 50The 9 low-order access permission bits of 51.Fa numask 52are used by system calls, including 53.Xr open 2 , 54.Xr mkdir 2 , 55.Xr mkfifo 2 56and 57.Xr mknod 2 58to turn off corresponding bits requested in the file mode 59(see 60.Xr chmod 2 ) . 61This clearing allows each user to restrict the default access to his files. 62.Pp 63The default mask value is S_IWGRP|S_IWOTH (022, write access for the 64owner only). 65Child processes inherit the mask of the calling process. 66.Sh RETURN VALUES 67The previous value of the file mode mask is returned by the call. 68.Sh ERRORS 69The 70.Fn umask 71function is always successful. 72.Sh SEE ALSO 73.Xr chmod 2 , 74.Xr mkdir 2 , 75.Xr mkfifo 2 , 76.Xr mknod 2 , 77.Xr open 2 78.Sh STANDARDS 79The 80.Fn umask 81function call is expected to conform to 82.St -p1003.1-88 . 83