Rescue System

When the system won't boot, turning rescue mode on or off gives you a way to get into the hard disk.

The rescue system is built on Rescatux. Once you've switched it on, start the system up, and your first job will be to pinpoint the original hard disk by entering the command below.

lsblk

From there, you'll see a list of hard disk devices—something like /dev/sda1, which should roughly match the size of your disk (say, 50GB).

After that, just mount the device to a folder, for example /mnt, using this command:

sudo mount /dev/sda1 /mnt

Carry out whichever changes are needed.

Once you've wrapped things up, turn rescue mode back off.