Linux Server Administration — Challenge

The goal#

Achieve the same outcome as Linux Server Administration, from an empty starting point, without the steps.

You have been handed SSH access to a server somebody else built. A colleague needs to deploy to it, the application directory is owned by root, and the disk is at 91%. Nobody documented any of it.

This is the most common first task in the job, and none of it is exotic — it is users, permissions, services and disk.

What must be true when you are done#

• A deploy user exists, belongs to a shared group, and can read the application directory without being root.
• /opt/app is owned by that group and group-writable, and a second user in the group can write to it.
• A service is installed, running, and comes back after reboot — proven by systemctl is-enabled.
• You can state which directory is consuming the most disk, with the command that told you.

Rules#

• Do not open the guided lab until you are finished, or until you have been stuck on the same thing for 20 minutes. Being stuck is the exercise; staying stuck is not.
• Official documentation is allowed and encouraged. In the job it is the first thing you open.
• Verify every criterion yourself with a command whose output you can read. "It looks right" is not a check.

If you get stuck#

Work in layers rather than restarting things:

1. What did you expect to happen, exactly?
2. What happened instead — the error text, not a paraphrase?
3. Which layer is that error from?
4. What is the smallest command that proves the layer below is fine?

That sequence is the skill this tier exists to build. The commands are lookup-able; the sequence is not.