Triggers a TimeMachine backup when you're connected to a specific Wireless Network.

./backwi.sh <ssid-that-triggers-backup> <backup-destination>

Copy backwi.plist to ~/Library/LaunchAgents/com.hazcod.backwi.plist and adapt the settings. Now enable it with launchctl load ~/Library/LaunchAgents/com.hazcod.backwi.plist. Logs can be viewed with tail -f /var/log/system.log.