Originally Posted by toonmariner
I have booted via recovery mode, option menu presents 'root - drop to root shell prompt'.
However using nano /etc/sudoers when I attempt to save edits it says file system is read-only!
Ah, that just means your recovery mode mounts the root filesystem read-only. It is a good thing; it means no changes are done (can
be done!) to the filesystem, unless you explicitly allow it. (If one of your disks crashes, it is better that the system does not attempt to do any fixes, or do any changes at all to the disk contents, before you have had the opportunity to safely copy (or try to copy) your files to some other storage media.)
Fortunately, you only need to run one command to switch from read-only file system to a normal one:
mount -o remount,rw /