linuxexpert-practice-labs/labs/lfcs/1-3-scheduling-jobs/README.md

LFCS 1.3: Scheduling jobs

A crontab for another user, a one-off job with at, a systemd timer, and who may use cron.

Before you start

The lab creates users alice and bob (password Lab-Pass-1) and makes sure cron is installed and running. at isn't set up; installing it and starting its service is part of task 2.

Tasks

1. As root, schedule /usr/bin/date >> /tmp/alice-date.log to run for user alice at 02:30 every weekday.
2. Schedule a job for 10 minutes from now that writes hello to /tmp/at-test. Check it's queued, write its job number to /root/lab-answers/2, then cancel it.
3. Create cleanup.service and cleanup.timer that delete files in /tmp/scratch older than 7 days (find /tmp/scratch -mtime +7 -delete) every day at 03:00, catching up after downtime. The timer must be enabled and running.
4. Stop user bob using crontab while everyone else still can.

Hints

• crontab -u alice -e, crontab -u alice -l.
• The at package and its atd service; at now + 10 minutes, atq, atrm.
• OnCalendar=, Persistent=, systemctl enable --now, systemctl list-timers, systemd-analyze calendar.
• /etc/cron.allow and /etc/cron.deny.