Also, sed can be used but not necessarily. If disk-space is very important, you can delete certain programs which perform task that can be done by others programs. Scripts are more powerful than aliases. But scripts eat disk-space and are loaded each time they are used. Aliases are faster than scripts because they are loaded from memory and not from disk.
Functions have power of scripts with the convenience to eat only memory-space.
To learn aliases and functions, you can look at the manpages.