diff --git a/doc/prog.sh b/doc/prog.sh
new file mode 100755
index 0000000..8f376b6
--- /dev/null
+++ b/doc/prog.sh
@@ -0,0 +1,63 @@
+#!/bin/sh
+# Copyright 2009 The Go Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file.
+
+# generate HTML for a program excerpt.
+# first arg is file name
+# second arg is awk pattern to match start line
+# third arg is awk pattern to stop processing
+#
+# missing third arg means print one line
+# third arg "END" means proces rest of file
+# missing second arg means process whole file 
+#
+# examples:
+#
+#	prog.sh foo.go                       # whole file
+#	prog.sh foo.go "/^func.main/"        # signature of main
+#	prog.sh foo.go "/^func.main/" "/^}/  # body of main
+#
+# non-blank lines are annotated with line number in file
+
+echo "<pre> <!-- $* -->"
+
+case $# in
+3)
+	if test "$3" = "END"  # $2 to end of file
+	then
+		awk '
+			BEGIN { printing = 0 }
+			'$2' { printing = 1; print NR "\t" $0; getline }
+			printing { if($0 ~ /./) { print NR "\t" $0 } else { print "" } }
+		'
+	else	# $2 through $3
+		awk '
+			BEGIN { printing = 0 }
+			'$2' { printing = 1; print NR "\t" $0; getline }
+			'$3' && printing { if(printing) {printing = 0; print NR "\t" $0; exit} }
+			printing { if($0 ~ /./) { print NR "\t" $0 } else { print "" } }
+		'
+	fi
+	;;
+2)	# one line
+	awk '
+		'$2' { print NR "\t" $0; getline; exit }
+	'
+	;;
+1)	# whole file
+	awk '
+		{ if($0 ~ /./) { print NR "\t" $0 } else { print "" } }
+	'
+	;;
+*)
+	echo >&2 usage: prog.sh file.go /func.main/ /^}/
+esac <$1 |
+sed '
+	s/&/\&amp;/g
+	s/"/\&quot;/g
+	s/</\&lt;/g
+	s/>/\&gt;/g
+'
+
+echo '</pre>'