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)
For the Love of Pipes (2019) (HN)
VCF East 2019 -- Brian Kernighan interviews Ken Thompson (2019)
Awesome UNIX - All the UNIX and UNIX-Like: Linux, BSD, macOS, Illumos, 9front, and more.
How Unix Works: Become a Better Software Engineer (2019)
Unix Toolbox - Collection of Unix/Linux/BSD commands and tasks which are useful for IT work or for advanced users. (HN)
Using ptrace To Call a Userspace Function