NCDU abbreviated as NCurses Disk Usage is a disk usage analyzer tool written entirely in C, most probably used when you don't have access to graphical interface & only have to deal with CLI.

Install it From source : #-Link-Snipped-#

Then open Terminal/Konsole & type :

 ncdu -x  

Example : (Here we are scanning entire root directory)

 ncdu -x / 

The scanning of files & folders will begin & you will see something like :
After scanning is over, you can see the space used in each & every directory under Root (/) [as we have used command to scan root] :

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