AFAIK it is not possible to execute local shell commands using javascript. It is too much of a security risk to have an untrusted script from the net execute local commands from your machine. OTOH if there are some plugins for your browser that allow you to access the local file system, you can try interfacing with them from javascript.
Anyway, found this hack for running command-line DOS applications in a windows environment using javascript:
http://www.winscripter.com/WSH/System/105.aspxHope this helps..