Shell / Bash

Before scripting, master the commands you'll type by hand every day.

Wiring one command's output into another's input is the secret to the command line's power.

Variables store values, and correct quoting prevents cryptic bugs that break scripts.

Turning your repeated commands into one runnable file is the first step to automation.

A smart script makes decisions: if the file exists do X, otherwise do Y.

Loops let you repeat the same action over hundreds of files or lines in one line.

Functions keep scripts tidy and DRY, and arguments make them flexible.

Most shell work is filtering and transforming text — grep, sed, awk are your weapons.

A silently failing script is a disaster — it must catch errors, stop safely, and tell you.

When handling structured data, arrays and parameter expansion give you powerful tools.

A professional script must be safe, readable, and tested — not just stacked commands.