sysop@hub:~/tools/linux-playground$
linux-playground
web01 has had a bad morning: the shop is down, a disk is full and something odd sits in the uploads folder. You are the new admin. The server is pretend and runs in this tab, with about sixty real commands, pipes, redirects, sudo and file permissions. Eighteen missions take you from ls to finding out how the attacker got in.
Enter runs the line. Tab completes commands and file names once you have typed something; with an empty line it leaves the terminal as usual. Arrow up brings back earlier commands, Ctrl L clears the screen.
what is in the box
| You can | With |
|---|---|
| Move around and read | ls cd pwd cat less head tail wc file stat tac |
| Search and filter | grep find sort uniq cut awk sed tr, joined with | |
| Change files | touch mkdir cp mv rm echo tee truncate, and > and >> |
| Permissions | chmod chown id whoami groups getent sudo usermod -L deluser passwd -l: files have owners and modes, and they are enforced |
| Look at the system | df du free ps top ss ip ping curl lsof uptime who history |
| Services | systemctl journalctl nginx -t sshd -t crontab -l ufw |
This is a teaching model, not an emulator: the commands know their common options, not all of them, awk only prints fields, and there is no editor (use sed -i and echo >>). The output is modelled on Debian. What you type stays in this tab, and is replayed when you reload it. Keep going with the Linux cheat sheet, users and permissions, the slow server walkthrough, the log reader and the config reviewer. Same idea for databases: the SQL playground.