Bash Automation: A Script You Can Trust — Challenge

The goal#

Achieve the same outcome as Bash Automation: A Script You Can Trust, from an empty starting point, without the steps.

There is a backup script on the server. It has 'run successfully' every night for eight months. The backup directory is empty.

It has been exiting 0 the whole time, because nothing in it ever checked whether anything worked.

What must be true when you are done#

• The script exits non-zero when any step fails, proven by deliberately breaking one.
• Running it twice does not corrupt or duplicate the previous backup.
• A backup older than the retention window is removed automatically.
• A failed run is visible without anyone reading the logs.

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.