• more on pipelines vs subshells

• remove some superfluous spaces

mksh.1

@@ -1,4 +1,4 @@
-.\" $MirOS: src/bin/mksh/mksh.1,v 1.182 2009/09/06 17:55:54 tg Exp $
+.\" $MirOS: src/bin/mksh/mksh.1,v 1.183 2009/09/06 18:17:51 tg Exp $
 .\" $OpenBSD: ksh.1,v 1.129 2009/05/28 06:09:06 jmc Exp $
 .\"-
 .\" Copyright © 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
@@ -406,6 +406,13 @@ last is piped (see
 .Xr pipe 2 )
 to the standard input of the following command.
 The exit status of a pipeline is that of its last command.
+All commands of a pipeline are executed in separate subshells;
+this is allowed by POSIX but differs from both variants of
+.At
+.Nm ksh ,
+where all but the last command were executed in subshells; see the
+.Ic read
+builtin's description for implications and workarounds.
 A pipeline may be prefixed by the
 .Ql \&!
 reserved word which causes the exit status of the pipeline to be logically