dynamic.py is a script that resolves a domain name to an IP address, then adds that IP address to your /etc/hosts file.

I log into my home server remotely, and I need to have a way to find its new IP address if it changes. I set up a dynamic DNS address, but it's cumbersome to type the whole thing.

dynamic.py will read your /etc/hosts file and look for special directives that tell it what domain names to look up.

The basic pattern is a pound, followed by the domain name you want to resolve, followed by one or more aliases that you want to resolve to the domain name, followed by the keyword DYNAMIC.

Example:

#subdomain.dynamic-dns.tld	server1-ext	nas1-ext	DYNAMIC

dynamic.py will change that to something like this:

#subdomain.dynamic-dns.tld	server1-ext	nas1-ext	DYNAMIC
70.71.72.73	server1-ext	nas1-ext # dynamically resolved

Then, I add dynamic.py to root's crontab, like so:

*/30 * * * * /path/to/dynamic.py

This re-resolves the domain name frequently enough for my purposes.