Bash

The shell is the oldest and most durable programming interface ever built. Every Linux server, every macOS machine, every CI pipeline, and every AI agent that runs code works through a shell. Learning Bash doesn't just give you a new tool — it gives you a key that opens most of the infrastructure on the planet.

The learning curve is shallow at first. A handful of commands gets you surprisingly far. Then it deepens: quoting rules, variable expansion, pipes and redirects, and script permissions. Each layer rewards you immediately — there's almost always something real you can do with it the same day you learn it.

Work through the Fundamentals track alongside this one. The mental models there — how programs run, what the filesystem is, how to read error messages — make the shell concepts here click much faster.

Three tiers

• Beginner — Shell basics: opening a terminal, navigating the filesystem, working with files, variables, writing your first script, and composing pipelines with pipes and redirects.
• Intermediate — Scripting & text: conditionals and loops in depth, functions, exit codes, grep/sed/awk, and building reliable text-processing pipelines.
• Advanced — Shell mastery & automation: arrays, parameter expansion, heredocs, traps and signals, cron scheduling, Makefiles, CI shell scripts, and debugging with set -x and shellcheck.

Pick a tier from the sidebar to begin.