...It emphasizes fluency: small habits and commands that compound into faster debugging, data wrangling, and system navigation. The content spans basic shell usage, text processing with tools like grep/sed/awk, networking and performance inspection, and advice for working safely with root and destructive commands. Many entries highlight lesser-known flags or idioms that save keystrokes or avoid pitfalls, and the list aims to be dense but scannable. It is written for Linux first while acknowledging macOS and Windows differences where relevant. ...