From what I can see,
rsc is an extra utility that would have come in with Radare1. See here.
I understand that ! causes Radare to execute a shell command so I therefore need the
rsc utility. However I cannot find it anywhere!
I'm using Radare2 0.10.0 compiled from git and Boomerang compiled from git as well.
Does anyone know what the state of these two tools working together is?