Hi,
We append init=/bin/bash to the kernel parameters when we want it to boot to a root shell instead of a normal boot to init level 3 or 4. This is
only done for thorough administrative tasks.
e.g. When you have lost your root password, or if you have lost your regular user password and you don't have root's password. In that case you boot into the root shell and use the passwd command.
https://wiki.archlinux.org/index.php/Kernel_parameters
https://wiki.archlinux.org/index.php..._root_password
So, generally it is a good idea to secure GRUB with a password so that no one gets access to the root shell by appending kernel parameters.
