A check you have to remember to run is a check you will stop running. This set covers keeping a check quiet by default, comparing two states, appending rather than overwriting, and giving cron everything it needs to run your job without you.
Each one is marked as you go, and the explanation arrives straight after, which is
the part worth reading.
4 questions, marked as you go.
Tasks
These need your own device. Run the command in Termux, then paste what it printed.
The marking looks at what the output means, so spacing, version numbers and
ordering do not matter. If you have not installed anything yet, the
lesson covers the setup.
Fire one alert, quietly
This compares two short lists, finds that one line was added, and appends a single stamped alert to a log. Run it twice if you like: the second run adds nothing, because nothing changed.
Run this in Termux
On your own device. Nothing on this page executes it. The command runs in
your terminal, and this box only reads what you paste back.
The whole thing is one if. When the two files match, the if does not run, and silence is the success case.
the alert line is stamped with the time it fired
the alert names the change it found
the alert log holds the entry
the commands actually ran
What a good answer looks like
One line in the alert log, starting with an ISO 8601 timestamp in UTC, then the word ALERT, then the change that was found. The line was appended, not overwritten, so earlier alerts would still be above it. A second run with no change adds nothing at all, which is the quiet-by-default behaviour the lesson builds. If the log is empty, the comparison did not detect the added line.
Marking your own work
Both halves of this are checked in your browser, with no server involved, so nothing
stops you from pasting output you did not run. The tasks are written so that the
easiest way to pass one is to actually do it and read the result, which is the whole
intention.