// learn · linux · rhcsa · 10 min

Linux command line essentials.

The shell is just a program that runs other programs. Watch commands run live in a simulated terminal — six steps from 'what's that $ symbol?' to chaining commands with pipes.

// command line essentials

A few commands and a few symbols get you 90% of what you'll need at the Linux shell every day. Watch the terminal below as you step through.

// before you start

you should know

·Roughly what a 'file' and a 'directory' (folder) are
·Knowing how to open a terminal app on your computer
·Nothing else — this is the on-ramp

by the end you'll

Move around the filesystem, create/copy/delete files, read files, send command output to files, and chain commands with pipes.

pace: 10 minutes

bash — terminal — step

student@laptop ~ $echo Hello# the simplest command

Hello

student@laptop ~ $whoami# who am I logged in as?

student

student@laptop ~ $date# what time is it?

Sun May 24 14:32:10 UTC 2026

student@laptop ~ $

step 1 / 6

The shell and the prompt

When you open a terminal you're running a 'shell' — a small program whose only job is to take a line of text from you, find the command you named, and run it. On Linux that shell is usually Bash. The $ symbol (called the prompt) means 'I'm ready for your next command'. Try typing the command name, optional flags starting with -, and arguments — all separated by spaces.

// key insight

The Unix philosophy: do one thing well, and connect with pipes. Every command you learn is a building block. grep alone is useful; cat | grep | sort | uniq -c | head is engineering. Build the habit of asking "is there a command that does just this one step?"

// survival commands · the daily 25

$pwdwhere am I?

$ls / ls -lalist (long, all)

$cd DIR / cd ..change dir / parent

$cd ~ / cd -home / previous dir

$touch FILEcreate empty file

$mkdir -p PATHmake dir(s) recursively

$cp SRC DSTcopy

$cp -r DIR DSTcopy directory

$mv SRC DSTmove or rename

$rm FILE / rm -rf DIRdelete (no recycle bin)

$cat FILEprint whole file

$less FILEpage through (q to quit)

$head -N / tail -Nfirst/last N lines

$tail -f FILEfollow as file grows

$grep PATTERN FILEfilter lines matching pattern

$wc -lcount lines

$sort / sort -nsort lines (numeric)

$uniq -cdedupe with counts

$find PATH -name PATfind files by name

$historyyour past commands

$man CMDfull manual for a command

$CMD --helpquick usage hints

$which CMDwhat binary will run?

$Ctrl-Cinterrupt the running command

$Ctrl-R, then typesearch command history

// check yourself

4 quick questions

You want to change to your home directory and see what's there. Which two commands?

You want to save the output of `ls /etc` into a file called list.txt — replacing whatever's already in list.txt. Which symbol?

Why does rm -rf / on Linux destroy almost everything?

What does the pipe character | do?

These aren't graded — they're just for active recall, which is what actually makes the lesson stick.

🎮

// now exercise it

Try the Bash Command Challenge

Reading is one thing — typing the command yourself is what makes it stick. 37 challenges across Easy, Medium, and Hard. Free play, no timer required.

play →

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