A few rewrites and additions.

man2/umask.2

@@ -1,7 +1,8 @@
 .\" 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
@@ -29,7 +30,8 @@
 .\" 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
@@ -42,7 +44,9 @@ umask \- set file mode creation mask
 .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),
@@ -94,8 +98,24 @@ A child process created via
 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)