.\" Hey Emacs! This file is -*- nroff -*- source.
.\"
-.\" Copyright (c) 1992 Drew Eckhardt (drew@cs.colorado.edu), March 28, 1992
-.\" and Copyright (c) 2006, Michael Kerrisk (mtk.manpages@gmail.com)
+.\" Copyright (c) 2006, 2008, Michael Kerrisk (mtk.manpages@gmail.com)
+.\" (A few fragments remain from an earlier (1992) version written in
+.\" 1992 by Drew Eckhardt <drew@cs.colorado.edu>.)
.\"
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" Modified Thu May 1 06:05:54 UTC 1997 by Nicolás Lichtmaier
.\" <nick@debian.com> with Lars Wirzenius <liw@iki.fi> suggestion
.\" 2006-05-13, mtk, substantial rewrite of description of 'mask'
-.TH UMASK 2 2006-05-13 "Linux" "Linux Programmer's Manual"
+.\" 2008-01-09, mtk, a few rewrites and additions.
+.TH UMASK 2 2008-01-09 "Linux" "Linux Programmer's Manual"
.SH NAME
umask \- set file mode creation mask
.SH SYNOPSIS
.BR umask ()
sets the calling process's file mode creation mask (umask) to
.I mask
-& 0777.
+& 0777 (i.e., only the file permission bits of
+.I mask
+are used), and returns the previous value of the mask.
The umask is used by
.BR open (2),
inherits its parent's umask.
The umask is left unchanged by
.BR execve (2).
+
+The umask setting also affects the permissions assigned to POSIX IPC objects
+.RB ( mq_open (3),
+.BR sem_open (3),
+.BR shm_open (3)),
+FIFOs
+.RB ( mkfifo (3)),
+and Unix domain sockets
+.RB ( unix (7))
+created by the process.
+The umask does not affect the permissions assigned
+to System V IPC objects created by the process (using
+.BR msgget (2),
+.BR semget (2),
+.BR shmget (2)).
.SH "SEE ALSO"
.BR chmod (2),
.BR mkdir (2),
.BR open (2),
.BR stat (2)
+.\" FIXME . eventually: .BR acl (5)