How to backup your all website files and folders before upgrade

First reach to the destination folder on which you want to perform this operation.
Then login to your linux terminal with username and password and run the following command :

tar -czvf bob_backup.tar.gz *

tar is format of the file, tar is used for compression of files.
c (--create)
z (tar has an option built into it to use 'gzip' to zip the file at the same time you make the tarball. If you add z to the options, and change the name of the file to create to a .gz extension)
v (--verbose-show what files they are)
f (--file -make a file - should always be the last option)