The FlashLite player does not support the "exec" fscommand, mainly because your typical mobile device doesn't want you executing arbitrary binaries on the device. Even if it were enabled, fscommand does not return the result of the execution.
However, on the chumby, we've enabled some capabilities that are available to movies running with local security. This means that the movie must be running on the device itself as the primary movie (like the Control Panel), but not from the network (like a widget). Both methods allow you to capture the stdout output of the command.
The first method is to use the XML object, with the protocol "exec://". For instance, you could do:
x = new XML();
x.onData = function(data) {
trace(data);
}
x.load("exec://ls");
The second option requires an ASnative call:
_backtick = ASnative(5,52); // syntax slightly different for Actionscript 2 - see the wiki
output = _backtick("ls");
trace(output);
The backtick method should be used only for extremely quick, synchronous calls, since the player is blocked during the execution and will cause and Actionscript timeout if it takes too long. The XML method should be used for longer, asynchronous calls, and is preferred as best practice.
Again - these only work for movies running with local security, not widgets. Running local binaries is potentially dangerous, so use at your own risk.