This is true. Some reasons why sh hasn't been replaced by LISP (for example) as the default Unix shell is because: - it was there first - grep awk etc are hea

This is true. Some reasons why sh hasn't been replaced by LISP (for example) as the default Unix shell is because: - it was there first - grep awk etc are heavily optimized and faster than their equivalents in most languages - the primary job of a shell is to run other programs, not to be the program. Scripting languages don't generally let you run a program just by typing the name and hitting enter. All that being said, you can set your login shell to be whatever you want in /etc/passwd, and you're free to login to your REPL of choice instead of sh if that's what you really want.