13 Fun Linux Commands to Play With (And 7 Dangerous Ones to Avoid)

Linux’s learning curve can be steep for beginners, so learning to amuse yourself with quirky commands is essential. Below are thirteen fun commands you can try.

1. sl command

Run sudo apt-get install sl and then sl to see a train moving across your screen.

You can also alias ls=sl for a harmless prank.

2. fortune command

Install with sudo apt-get install fortune (or fortune-zh for Chinese poems) and run fortune to display a random quote, joke, or poem.

3. cowsay command

Install with sudo apt-get install cowsay and run cowsay "I am not a cow, hahaha" to print a speech bubble from an ASCII animal.

Use cowsay -l to list available animals and cowsay -f tux "Message" to choose one. Combine with fortune | cowsay for random messages.

4. cmatrix command

Install with sudo apt-get install cmatrix and run cmatrix to display a Matrix‑style falling‑code animation.

5. figlet / toilet commands

Install with sudo apt-get install figlet toilet. Use figlet "Your Text" or toilet -f mono12 -F gay "a girl" to create colorful ASCII banners.

6. oneko command

Install with sudo apt-get install oneko and run oneko to see a cat chasing your mouse pointer.

7. xeyes command

Install and run xeyes to display a pair of eyes that follow the cursor.

8. yes command

Run yes "I am awesome" to output the string endlessly until stopped with Ctrl+C.

9. cal 9 1752

The cal command prints a calendar; the September 1752 example shows the historic calendar reform.

10. shred command

Use shred to overwrite files, making data recovery difficult.

11. factor command

Run factor to factor numbers; it’s a simple arithmetic utility.

12. aptitude moo series

Run various aptitude -v moo levels to display a playful ASCII cow.

13. free the fish

Press Alt+F2 and type free the fish to launch a fish animation on the desktop.

14. rm -rf /

The rm command with -r -f recursively and forcefully deletes files. Executing it at the root directory wipes the entire system. Modern systems often require the --no-preserve-root flag to bypass safety checks.

15. Bash fork bomb

Running :(){ :|: & };: repeatedly spawns new Bash processes until system resources are exhausted, causing a crash.

16. Overwrite hard drive

Redirect any command’s output to a raw device, e.g., any_command > /dev/hda, to corrupt the disk.

17. dd to wipe disk

Use dd if=/dev/zero of=/dev/hda to write zeros to the entire drive, effectively erasing it.

18. Move everything to /dev/null

Running mv / /dev/null or > mv /dev/null sends all data to the null device, destroying it unless a backup exists.

19. Format the wrong drive

Running mkfs.ext3 /dev/hda formats the specified device with ext3; doing this on the primary drive erases all data.

20. Kernel crash commands

Commands like dd if=/dev/random of=/dev/port, writing to /proc/sys/kernel/panic, or dumping data to /dev/mem can trigger kernel panics.

21. Unverified scripts

Downloading and piping an untrusted script directly to sh (e.g., wget https://example.com/script.sh -O- | sh) is extremely dangerous and should be avoided.

These examples illustrate both entertaining and hazardous Linux commands, reminding users to experiment responsibly and always understand a command before executing it.