Create/Execute External Tool Command From Plugin

Basically from a plugin, actually the new scripting console (which is awesome!!), I want to do some calculations then execute some random unix command and display the results.
There has to be a simple way to do this as the external tools do exactly what I want. I just need to do it from inside a plugin.

Something like...
ExternalTool.getInstance().exec("ls") // will open the terminal/console in intellij and stream the output of the command

Any pointers/direction?

Thanks!