Originally from Mike Gancarz’s book, here are the 9 primary tenets of Unix.
Small is Beautiful
Make Each Program Do One Thing Well
Build a Prototype as Soon as Possible
Choose Portability Over Efficiency
Store Data in Flat ASCII Files
Use Software Leverage to Your Advantage
Use Shell Scripts to Increase Leverage and Portability
Avoid Captive User Interfaces
Make Every Program a Filter
I think this is one of the biggest ideas in computer science, and I don’t feel it gets the respect it deserves.