I ran into the following error while running a script that was performing backups of files via rsync over ssh.
If you've ever worked with Debian or Ubuntu servers, you've very likely had to set up a firewall at some point or the other. However, any changes that are made are not saved and loaded if the server is ever rebooted. The following is a quick guide on how to get this happening:
(root or sudo access is required)
If you run into the following error message when attempting an
iptables-restore < my.rules:
iptables-restore v1.4.8: no command specified
then the problem is that you have very likely just copied and pasted stuff into
my.rules which has led to some dodgy line-breaks terminating blank lines in the file.