Step-by-Step Guide to Using GRUB to Edit the Boot Line

1. Reboot Your System:

   • Restart your computer and wait for the GRUB menu to appear. If it doesn’t show up by default, hold the Shift key during boot.

2. Edit the GRUB Boot Parameters:

   • Once the GRUB menu is visible, highlight the default boot entry (usually the first option, which is your main Ubuntu system).
   • Press e to edit the boot parameters for the selected boot entry.

3. Modify the Boot Line:

   • Now you will see the boot configuration for your selected Ubuntu kernel.
   • Look for the line starting with linux. This is where the boot parameters are defined.
   • Use the arrow keys to navigate to the end of this line and add the following text (after the existing parameters):

   init=/bin/bash

   This tells the system to boot directly into a bash shell as the root user, bypassing the usual login process.

4. Boot with the Modified Parameters:

   • After adding init=/bin/bash, press Ctrl + X or F10 to boot with these settings. Your system will now boot to a root shell without asking for a password.

5. Remount the Filesystem:

   • Once you are at the root shell prompt, the filesystem will be mounted in read-only mode. To make changes, you'll need to remount it as read/write:

   mount -o remount,rw /

6. Reset Your Password:

   • Now, reset your user’s password using the passwd command. Replace your_username with your actual username:

   passwd your_username

   • Enter a new password when prompted. Type it again to confirm.

7. Reboot Your System:

   • After resetting the password, reboot the system to go back to normal boot:

   exec /sbin/reboot

   Or you can just type:

   reboot

What Happens Next

• Your system will reboot normally, and you should now be able to log in using your new password.

Summary:

• You use F2 (or e) in the GRUB menu to edit the boot line temporarily.
• Add init=/bin/bash to boot straight into a root shell.
• Reset your password using passwd your_username.