added documentation pages from Dave Korn's old web site

docs/ksh/scripts/env.txt

@@ -0,0 +1,66 @@
+#! /usr/bin/ksh
+# shell version of env command
+case $(getopts '[-]' opt '--???man' 2>&1) in
+version=[0-9]*)
+    usage=$'[-?@(#)env (AT&T Labs Research) 1999-05-20\n]
+        [-author?David Korn <dgkorn@gmail.com>]
+        [-license?http://www.research.att.com/sw/tools/reuse]
+        [+NAME?env - set environment for command invocation]
+        [+DESCRIPTION?\benv\b modifies the current environment according
+		to the \aname\a\b=\b\avalue\a arguments, and then
+		invokes \acommand\a with the modified environment.]
+	[+?If \acommand\a is not specified, the resulting environment
+		is written to standard output quoted as required for
+		reading by the \bsh\b.]
+	[i:ignore-environment?Invoke \acommand\a with the exact environment
+		specified by the \aname\a\b=\b\avalue\a arguments; inherited
+		environment variables are ignored.  As an obsolete feature,
+		\b-\b by itself can be specified instead of \b-i\b.]
+	[u:unset]:[name?Unset the environment variable \aname\a if it was
+		in the environment.  This option can be repeated to unset
+		additional variables.]
+
+	[name=value]... [command ...]
+
+	[+EXIT STATUS?If \acommand\a is invoked, the exit status of \benv\b
+		will be that of \acommand\a.  Otherwise, it will be one of
+		the following:]{
+	        [+0?\benv\b completed successfully.]
+	        [+126?\acommand\a was found but could not be invoked.]
+	        [+127?\acommand\a could not be found.]
+	}
+        [+SEE ALSO?\bsh\b(1), \bexport\b(1)]
+    '
+    ;;
+*)
+    usage='iu:[name] [name=value]... [command ...]'
+    ;;
+esac
+clear=
+while	getopts  "$usage" var
+do	case $var in
+	i)	clear=1;;
+	u)	command unset $OPTARG 2> /dev/null;;
+	esac
+done
+#[[ $var == "" ]] || exit 1
+shift $((OPTIND-1))
+if	[[ $1 == - ]]  # obsolete form
+then	clear=1
+	shift
+fi
+if	[[ $clear == 1 ]]
+then	typeset +x $(typeset +x)
+fi
+while	true
+do	case $1 in
+	*=*)	export "$1";;
+	*) break;;
+	esac
+	shift
+done
+if	(( $# >0 ))
+then	exec "$@"
+else	export
+	exit 0
+fi