Discoverability is definitely a feature of any decent post-2000 *nix terminal environment. Man and apropos get you a long way. The near ubiquity of --help as

Discoverability is definitely a feature of any decent post-2000 *nix terminal environment. Man and apropos get you a long way. The near ubiquity of --help as a flag helps too. Well managed program distributions will even tell your shell how to tab-complete what it wants. MOST CRUCIALLY, though, the text of a command line or config snippet can be pasted, emailed, im'ed, blogged, and found with a search engine! Try describing how to navigate through a moderately complex gui in text or by phone... it's a disaster.