“What command should I run?” is the wrong first question. Systematic beats clever, every time.
An application on a Linux server stops working. A beginner asks “what command fixes this?” A DevOps engineer instead works through a sequence — and almost every step uses a command from the earlier chapters.
1 · Where am I?
pwd↓
2 · What’s here?
ls -la↓
3 · Check the logs
tail -n 50 application.log↓
4 · Search for errors
grep ERROR application.log↓
5 · Is it even running?
ps aux | grep application↓
6 · Is the box overloaded?
top↓
7 · Is it actually responding?
curl http://localhost:8080↓
8 · Can it reach its files?
ls -l config.txt↓
9 · Are permissions the problem?
chmod / ls -l↓
10 · Can it talk to other machines?
ping server-nameThis is the beginning of Linux-based troubleshooting — a genuinely core DevOps skill, and one that’s really just “navigation + viewing + processes + permissions + networking” chained together in order.
