diff --git a/dist/isum.awk b/dist/isum.awk
new file mode 100644
index 0000000..db782c8
--- /dev/null
+++ b/dist/isum.awk
@@ -0,0 +1,92 @@
+# Summarize the installation log, printing errors along with
+# enough context to make sense of them.
+
+BEGIN {
+#	print verbose 
+	cd = ""
+	out = "/dev/stdout";
+}
+
+debug { print "# " $0 }
+
+/^$/ { next }
+
+/^\* /{
+	if(debug) print "% mark"
+	print >out
+	fflush(out)
+	cmd = ""
+	printtabs = 1	# print indented lines immediately following
+	errors = 0
+	next
+}
+
+/^	/ && printtabs {
+	print >out
+	fflush(out)
+	next
+}
+
+{ printtabs = 0 }
+
+/^(9a|9c|9l|9ar|9?install|cp|rm|mv|mk|9 yacc|9 lex|9 rc|do|for i|if|mk|gcc|cpp|cp|sh|cmp|rc|\.\/o)($|[^:])/ {
+	if(debug) print "% start"
+	errors = 0
+	cmd = ""
+	if(!verbose)
+		cmd = cmd cd
+	cmd = cmd $0 "\n"
+	next
+}
+
+/^cd / {
+	if(debug) print "% cd"
+	errors = 0
+	if(verbose){
+		print >out
+		fflush(out)
+	}
+	cd = $0 "\n"
+	cmd = ""
+	next
+}
+
+{
+	cmd = cmd $0 "\n"
+}
+
+errors {
+	if(debug) print "% errors"
+	printf "%s", cmd >out
+	fflush(out)
+	cmd = ""
+	next
+}
+
+/^(	|then|else|fi|done|[ar] - [^ ]*\.o$)/ {
+	next
+}
+
+/^(up to date|nothing to see|assuming it will be|loop not entered|conflicts:)/ {
+	if(debug) print "% skip1"
+	next
+}
+
+/is up to date/ {
+	next
+}
+
+/(nodes\(%e\)|packed transitions)/ {
+	if(debug) print "% skip2"
+	next
+}
+
+{ 
+	# unexpected line 
+	if(debug) print "% errors1"
+	errors = 1
+	printf ">>> %s", cmd >out
+	fflush(out)
+	cmd = ""
+}
+