Rescue System

Should your system fail to boot, turning on rescue mode lets you reach the hard disk directly. 

The rescue environment relies on Rescatux. Once you've enabled it and booted up, your first task is to identify the main hard disk. You can do that by running the command:

lsblk

You'll see a list of disk devices; for instance, /dev/sda1 will typically correspond to your hard drive's size (e.g., 50GB).

Next, just mount that device to a directory like /mnt with this command:

sudo mount /dev/sda1 /mnt

Now you can make any necessary changes to your files.

Once you've completed your work, disable rescue mode.