Found in chiark:/usr/local/lib/user-cgi/cgi/check

diff --git a/www-cgi/check b/www-cgi/check
new file mode 100755 (executable)
index 0000000..fca7431
--- /dev/null
+++ b/www-cgi/check
@@ -0,0 +1,6 @@
+#!/bin/sh
+echo "Content-type: text/plain"
+echo
+
+echo "ucgi check - args:" "$@"
+printenv | sort