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Scheduling Jobs

Updated Mar 27, 2021 ·

Tasks​

  1. Ensure systemd timer cleans up the tmp files..
  2. Run a cron job that will issue the command "touch /tmp/cronfile" 5 minutes from now.
  3. Use at to schedule a job to power off your system at a convenient time laer today.

Solution​

1. Systemd timer cleans up the tmp files​

Check if the systemd-tmpfiles-clean timer is enabled

sudo systemctl status systemd-tmpfiles-clean.timer

Enable the timer if it is not already enabled

sudo systemctl enable systemd-tmpfiles-clean.timer
sudo systemctl start systemd-tmpfiles-clean.timer

Verify the timer is active

sudo systemctl status systemd-tmpfiles-clean.timer

2. Run a scheduled crob job​

Run a cron job that will issue the command below 5 minutes from now.

touch /tmp/cronfile

Open the crontab editor

crontab -e

Add the following line to schedule the cron job

# (Replace `date` and `time` with the current time plus 5 minutes)
MM HH DD MM * touch /tmp/cronfile

Where:

  • MM is the minute (current minute + 5)
  • HH is the hour
  • DD is the day of the month
  • MM is the month

For example, if the current time is 14:00, the line would look like this:

05 14 * * * touch /tmp/cronfile

Save and exit the editor.

3. Schedule power off using at​

Install at if it is not already installed

sudo yum install at
sudo systemctl enable atd
sudo systemctl start atd

Schedule the power-off job

echo "sudo poweroff" | at HH:MM

Replace HH:MM with the time you want to power off the system. For example, to power off at 10:30 PM:

echo "sudo poweroff" | at 22:30