The dynamic nature of GRUB helps us to alter its configuration before loading the operating system. Also, it doesn't need to reinstall the bootloader into MBR each time we make modifications to the menu.lst file. Working on GRUB's command line interface is similar to a bash terminal interface. In order to switch to the GRUB's command line interface from the bootloader, press C. Then you will get a prompt as shown below: Type Help to take a look at the available commands. In order to boot a kernel, issue the following commands one by one: For just editing the current as entry, select the required entry and press E Then make the required modifications and press B to boot with the modified configuration.