Local CLI

Everything so far works the same in a browser-based sandbox. Real systems work involves your own machine, so this lesson is a guided tour of what to set up locally.

A real terminal, and WSL on Windows

macOS and Linux both ship with a real terminal out of the box. On Windows, install WSL (Windows Subsystem for Linux), which runs a genuine Linux environment alongside Windows:

wsl --install

This gets you a real bash shell, real Linux filesystem semantics, and every command in this course working exactly as shown, rather than an approximation.

Manual pages

Every standard command ships with a full manual, more detailed than --help:

man ls
# space/f = next page, b = previous page, q = quit

Interactive pagers

Commands like man, and tools like less, are pagers, they show output one screen at a time instead of dumping it all at once:

cat huge_log.txt | less   # scroll through with arrow keys, q to quit

Processes

Every running program is a process, with a unique process ID (PID):

ps aux            # list running processes
top                # live, updating view of processes and resource use
kill 4821          # ask a process to stop, by PID

Users, root, and sudo

Linux is multi-user by design. Regular users can't modify system files or other users' data, that requires the root user, the one account with unrestricted access:

whoami             # your current user
sudo apt update    # run one command AS root, temporarily, with a password prompt

sudo ("superuser do") is how you borrow root's power for a single command without permanently logging in as root, which is exactly the safer, auditable model almost every real system uses.