Today I had to manually rotate a couple of logs since they had generated a filesize of over 1.8GB of pure text.

This was done by issuing the command

logrotate /etc/logrotate.d/file_to_be_rotated

In my case I had to rotate my firewall log /var/log/firewall described in a custom made file, /etc/logrotate.d/firewall

logrotate -v -f /etc/logrotate.d/firewall

-v Verbose logging
-f Force rotation of logs even if not needed