Learning What’s Happening on Your System

A few Unix commands can provide you with answers to questions about your system: “Who is logged in?” “What are they doing?” “What jobs are taking up all my CPU cycles?” “How long has my system been up?”

• uptime tells you how long it has been since you last restarted and what your workload is.

• who tells you who is logged into your system, where they’re logged in from, and when they logged in.

• w tells you who is online and what they are doing.

• last tells you who has logged onto your computer.

• ps and top tell you what jobs are running on your computer.