Try to make a shell using simple programming language Nasal.
If you feel hard to use this shell, that's right.
bash, zsh, sh, oh-my-gosh? TRASH!
First you should get Nasal interpreter.
Then use this command to run:
./nasal -op -e main.nas
It is a programming language designed by Andy Ross. Mainly used in a famous flight simulator FlightGear. I re-write a new interpreter for this language and use it to run this shell.