- finding commands
	- built-in commands
	- find with given path only if there is a '/'
- variables
	- uses $PATH in env.variables instead of envp
- 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)
- fix
	- empty variables aren't freed
	- need to free value returned by readline
	- the builtins should get all arguments and check if they're good
	- command `echo "hello` with unclosed quotes

(unnecessary part)
- working history (rl_* functions?)
	- '<<' with history?

(also search TODO and FIXME in the files)
(also check if it works at the cluster (might need libreadline-dev))