Today I have given the responsibility to setup Ubuntu machine for school group. Nowadays kids are very smart and they can do the system level changes easily if they know the root password or they can start the machine as a dingle user. I though to disable single user mode / recovery mode booting to make it little bit more secure
To achieve the same I have followed following step which help me to remove single user / recovery mode from GRUB permanently.
Step 1 Open a terminal with Ctrl+Alt+T shortcut and type this command and then hit Enter
gksu gedit /etc/default/grub
Step 2 The above command will open grub default file in gedit text browser. Search for a section like this one
# Uncomment to disable generation of recovery mode menu entries #GRUB_DISABLE_RECOVERY="true"
Remove the # mark from the line #GRUB_DISABLE_RECOVERY=”true”. The changed section should look like this
# Uncomment to disable generation of recovery mode menu entries GRUB_DISABLE_RECOVERY="true"
Save the file by pressing Ctrl+S then exit Gedit.
Step 3 Then again going to the terminal, execute the below command:
Step 4 Restart to see that the recovery option has gone.