commandrun от Achim Abeling, FourThreeSeven, Berend

Injects an object CommandRun into every loaded page which provides a function run which allows to run commands of the operating system.
Allowed commands must be defined using the preference "extensions.commandrun.allowedcommands" which must be a JSON array, e.g. ["/usr/bin/touch","/bin/ls"].
You may then run the commands with javascript code like this:
CommandRun.run("/usr/bin/touch",["/tmp/commandruntest"]);

It requires installing a Native Messaging App as addons.mozilla.org won't install native apps. An App is included in the source.