crontab

Many companies offer free dynamic DNS. But since I use DomainDiscount24, I also use their dynamic DNS service. To update the IP address of vpn.jeltsch.org, I need to send an https request to a specific URL, including a password and the hostname for which I want the update:
https://dynamicdns.key-systems.net/update.php?hostname=vpn.jeltsch.org&password=12345678&ip=auto

We have a shared directory (/home/shared) on our computer and a usergroup called "shared". The purpose is that we put things there that should be accessible (including writable) to several users of the system. If one user puts a file there, it can be read by others but not e.g. deleted. In order to fix this, we edited the crontab to execute every 5 minutes the following two commands:

chgrp -R shared /home/shared
chmod -R 744 /home/shared

In order to do this we edited (as root of course) the /etc/crontab file by adding the line: