Comment 20 for bug 262152

adsmith's script doesn't work on Precise so I've reworked it and removed the dependency on naming interfaces. My script will act whenever any "eth*" interface comes or goes. It also logs to "/var/log/NetworkManager.log".

Install to /etc/NetworkManager/prefer_wired_over_radio.sh

Once copied to that location do:

sudo chmod ug+x /etc/NetworkManager/prefer_wired_over_radio.sh
sudo ln -s /etc/NetworkManager/prefer_wired_over_radio.sh /etc/network/if-up.d/00prefer_wired_over_radio
sudo ln -s /etc/NetworkManager/prefer_wired_over_radio.sh /etc/network/if-post-down.d/00prefer_wired_over_radio

Watching the log-file whilst disconnecting and then reconnecting the wired interface will show something like this:

# tail -f /var/log/NetworkManager.log
2013-02-23-15:28:34 prefer_wired_over_radio eth0 NetworkManager stop post-down
2013-02-23-15:28:34 Re-enabling Wireless interfaces since wired went away
2013-02-23-15:28:42 prefer_wired_over_radio wlan0 NetworkManager start post-up
2013-02-23-15:28:52 prefer_wired_over_radio eth0 NetworkManager start post-up
2013-02-23-15:28:52 Disabling Wireless interfaces whilst wired is active
2013-02-23-15:28:52 prefer_wired_over_radio wlan0 NetworkManager stop post-down