This kind of thing is sooo frustrating. Following these instructions to install Edimax wifi dongle, and I'm stuck at 'configure wireless network connection'. The command
sudo vi /etc/network/interfaces opens the file in a viewer, either in the GUI or from command line. But there are no instructions for how to edit/save/exit and anything you enter seems to change the file. The only way to ecxit is to pull the power plug and afterwards the pi fails to load - it just rotates endelssly through the installation sequence - requiring a fresh installation. I've had to reinstall twice now because of this.
So please: 1. are there any instructions for the vi app? For instance this guide makes no mention. 2. is there any way to undo changes in vi?