- working history (rl_* functions?)
	- '<<' with history?
- finding commands
	- built-in commands
	- relative/absolute paths
- signals
	- ^C, ^D, ^\
- variables
	- normal variables
	- environment variables
	- $?
- pipes
	- no calls (like `$ < input_file > output_file`)
- builtins:
	- echo		(with option -n)
	- cd [path]
	- pwd		(with no options)
	- export	(with no options)
	- unset		(with no options)
	- env		(with no options or arguments)
	- exit		(with no options)