Unix is pretty amazing for many things.
I mostly love its philosophy of making small composable tools that do one thing and do it well.
/dev/tty is a synonym for the controlling terminal (if any) of the current process.
Shell scripts and tools
AT&T Archives: The UNIX Operating System - Awesome lookback on history of UNIX.
cicada - Simple Unix shell written in Rust.
Test your sysadmin skills
The History of Unix, Rob Pike (2018)