It's like what (I think) Localoid is saying. It's not exactly like BASH, considering it's more object oriented, but it is very BASH-similar. ...
Interestingly enough, Chrome OS includes the Chrome shell, "crosh", (which offers minimal functionality) In developer mode, a full-featured Bash shell can be opened Bash shell via Vt-2 (Virtual Terminal) and is also accessible via the crosh command "shell".