Lion Cipher Lab
Read your Linux logs with journalctl
- Foundations
- Beginner
- ~30 min
- Free · no account required
Why it matters
Logs are where a Linux machine writes down what actually happened — every service start, every failed login, every crash — and reading them is the first real skill of defending or troubleshooting a box. Learn `journalctl` once and you can walk up to almost any modern Linux system and answer "what went wrong, and when" in seconds.
What you'll learn
- reading system logs
- journalctl
- systemd journal
- incident triage
- log filtering
Steps in this lab
- What the journal is (and where it lives)
- Take your first look
- Narrow by service and by severity
- Filter by time, watch live, and search
- Kernel messages and structured output
- Check size and rotate the journal
- When you'd reach for this — and why it matters