If anyone has discovered a reliable technique that detects a keypress event (= character available on stdin) in the Tcl loop, please let me know. The Ctrl/C solution is a kludge.
Ivan Pepelnjak, CCIE#1354, is the chief technology advisor for NIL Data Communications. He has been designing and implementing large-scale data communications networks as well as teaching and writing books about advanced technologies since 1990. See his full profile, contact him or follow @ioshints on Twitter.