There are not many operating systems that anyone has ever described as ‘fun’. Indeed, the friction and labor of development under most other environments has been aptly compared to kicking a dead whale down the beach.^[8] The kindest adjectives one normally hears are on the order of “tolerable” or “not too painful”. In the Unix world, by contrast, the operating system rewards effort rather than frustrating it. People programming under Unix usually come to see it not as an adversary to be clubbed into doing one's bidding by main effort but rather as an actual positive help.

This has real economic significance. The fun factor started a virtuous circle early in Unix's history. People liked Unix, so they built more programs for it that made it nicer to use. Today people build entire, production-quality open-source Unix systems as a hobby. To understand how remarkable this is, ask yourself when you last heard of anybody cloning OS/360 or VAX VMS or Microsoft Windows for fun.