javascript - How to execute a command in a Firefox Add-On? -

i quite new writing firefox add-ons, still, got point patched working extension, except core of it.

at point in code, need execute system-command on file. i've found snipped on web , tried adapt it, without luck. xpi/components/script.js:

var cmd = '/usr/bin/somecommand'  var args = ['-option', 'value', f.path ];  var execfile = components.classes["@mozilla.org/file/local;1"].createinstance(components.interfaces.nsilocalfile); var process = components.classes["@mozilla.org/process/util;1"].createinstance(components.interfaces.nsiprocess);  execfile.initwithpath(cmd);  if (execfile.exists()) {     process.init(execfile);     process.run(false, args, args.length); } 

can tell me what's wrong here? i've assembled command , i've got filename can't firefox execute code snippet.

is execfile, initwithpath, createinstance, etc. stuff needed?? want execute command in cli:

$ somecommand -option value filename 

works fine me cmd , args changed to:

var cmd = '/usr/bin/say'; var args = ['hello', 'world' ]; 

as neil says, need more info troubleshooting. enable error console , check if there messages there.