7.20: First Cron Job

Information

The software utility cron is a time-based job scheduler in Unix-like computer operating systems. People who set up and maintain software environments use cron to schedule jobs (commands or shell scripts) to run periodically at fixed times, dates, or intervals. It typically automates system maintenance or administration—though its general-purpose nature makes it useful for things like downloading files from the Internet and downloading email at regular intervals. (from Wikipedia)

We can set up a cron job to run our ip address emailer every time we boot our raspberry pi. That way if we forget to attach the monitor, or want to connect remotely, we have its IP address to connect. To do this at your prompt type the following:

pi@hostname:~ $ crontab -e

 

The first time you do this, you will be prompted to select your favorite editor. We will select 1 for the nano editor.  At the bottom of the document add the following line.  Note, you will need to edit this to the path and name of your file that emails the IP address.

@reboot sleep 60 && python3 /home/pi/python_programs/send_my_ipaddress.py

Now reboot your Pi and see if you get an email with the IP address.  If so, you are done with this part of the assignment.