Install drivers in ubuntu using command line

First, you need to get superuser permission.

sudo passwd root

this will prompt you to enter your normal login password

then the system will ask for new set of the password to assign as the sudo password.
Done...

In order to install wifi drivers type, this commands.

this will prompt all the required drivers' list.

sudo ubuntu-drivers list

Will show all the driver packages which apply to your current system. You can then

sudo ubuntu-drivers autoinstall 

to install all the packages you need, or you can do:

sudo ubuntu-drivers devices

to show you which devices need drivers and their corresponding package names.

after identifying the required drivers you can issue the 

sudo apt-get install <driver name>

This will do the trick. Enjoy.