Quote Originally Posted by twoHats
The only thing i havn't seen mentioned is the shell. Running different CL shells can have a pretty heavy impact - so if you are practicing Linux on UNIX - be sure to run the same shell on UNIX that is being run on the target Linux system (usually BASH).

HTH
i was thinking the same thing. you should be able to use bash on different UNIX flavours (if you don't want to pay, i'd suggest BSD), and also linux which should keep the experience similar. i don't know huge amounts about UNIX tbh, so don't take my word as law.