Ubuntu – tool for validating /etc/network/interfaces files

configurationnetworkingserver

I always like to test new config files before deploying them–with tools like apachectl configtest and named-checkconf.

It's rare that mistakes crop up, but catching them before deployment eliminates any impact. The one that has bit me in the backside several times is /etc/network/interfaces; I can't seem to find a tool to test it, and restarting the network on a remote machine only to discover it's no longer reachable is quite annoying–especially when we use a lot of bonding and bridging.

Best Answer

To expand upon @jdthood's answer...

If the interface is already up, you can still use this method to validate the /etc/network/interfaces file. For example, assuming you have an error, you may see something like this:

$ sudo ifup --no-act eth0
/etc/network/interfaces:11: unknown method
ifup: couldn't read interfaces file "/etc/network/interfaces"

Apparently there's an error on line 11. Great. Thank heavens I didn't bounce the networking only to lose SSH access!

If all is fine, you will see:

$ sudo ifup --no-act eth0
ifup: interface eth0 already configured
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