If you need to automate the retrieval of the latest Nagios version path to download this is how I do it.
Nothing fancy and it breaks if they change the sourceforge site but we can fix when that happens 🙂
curl -v http://www.nagios.org/download/core/thanks/ 2>&1 | grep tar\.gz | cut -d \” -f 2 | sort -r | head -n 1
Result:
http://prdownloads.sourceforge.net/sourceforge/nagios/nagios-3.4.1.tar.gz
Of course this comes in handy when pulling for the clients being monitored so by extension:
 curl -v http://www.nagios.org/download/plugins/ 2>&1 | grep tar\.gz | cut -d \” -f 2 | sort -r | head -n 1
Result:
http://prdownloads.sourceforge.net/sourceforge/nagiosplug/nagios-plugins-1.4.16.tar.gz
Getting the files in a script is as easy as :
curl -v http://www.nagios.org/download/plugins/ 2>&1 | grep tar\.gz | cut -d \” -f 2 | sort -r | head -n 1 | xargs wget
Ping me if this stops working for you.
Enjoy.