Ubuntu – the difference between booting into Ubuntu normally and in recovery mode

The instruction Remove existing kernel options from the linux line and add single refers to changing the line

linux /boot/vmlinuz-3.5.0-26-generic root=<uuid> ro ipv6.disable=1 quirt splash $vt_handoff

to

linux /boot/vmlinuz-3.5.0-26-generic root=<uuid> single

which will boot up and show a text-mode terminal with root permissions ("single-user mode") from which fixes can be made.

The Ubuntu recovery mode is entered by setting linux options thusly:

linux /boot/vmlinuz-3.5.0-26-generic root=<uuid> ro recovery nomodeset

This provides a menu which automates some common system fixes, or lets you access a root shell as the single option would.

Finally i am able to resolve this issue...went thru each and every file under /etc/grub.d/ directory and got rid of the entries not needed and then ran 'sudo update-grub'. I went into 25_custom and wiped all the entries into which were not needed(to boot into at the time of startup - like all the unnecessary EFI entries).

sudo gedit  /etc/grub.d/25_custom
sudo update-grub

Please make sure to make a backup of the files you are editing. Make sure that you are not storing any of the backup files starting with 25_custom...if you store it with 25_custom_today'sdate etc....EFI boot loader will still read the entries from that....For folks who have HP Laptop - this will definitely work for you.Thanks for all your help.

Update Faced this issue again with my Dell XPS Desktop. This time I need to do the same for custom_40 and custom_41. Please refer to anything under /etc/grub.d to find out the issues specific to your machine.

Another alternative to do this: Use grub-customizer - graphical user interface

sudo add-apt-repository ppa:danielrichter2007/grub-customizer
sudo apt-get update
sudo apt-get install grub-customizer
grub-customizer

Now highlight the entry and remove it Save the changes once done.

With next reboot - you can check those unwanted entries are gone. and good part about grub-customizer is that in the right side - it has the removed items - one can revert back some or all of them if you have deleted something by mistake. Also don't forget to purge the old kernels so that you can save on disk space also.