Special Characters
http://www.collados.org/asix1/m01/tu1/special_characters.html
VirtualBox/Shared Folders

https://help.ubuntu.com/community/VirtualBox/SharedFolders
VirtualBox/How to resize a Virtual Drive
https://forums.virtualbox.org/viewtopic.php?f=35&t=50661
https://www.virtualbox.org/manual/ch08.html#vboxmanage-modifyvdi
Enable Gnome Root Login (for Debian 9)
https://economictheoryblog.com/2017/05/02/how-to-enable-gui-root-login-in-debian-9/
Note:
At this point I should warn you that using the root account is dangerous as you can ruin your whole system
Enable Sudo
https://www.digitalocean.com/community/tutorials/how-to-add-delete-and-grant-sudo-privileges-to-users-on-a-debian-vps
https://wiki.debian.org/sudo
http://milq.github.io/enable-sudo-user-account-debian/

Note: At this point I should warn you that using sudo is dangerous as you can ruin your whole system
Working with grep
https://www.howtoforge.com/tutorial/linux-grep-command/
Creating a bootable USB drive from an ISO image
https://www.turnkeylinux.org/blog/iso2usb
Answers to questions in some practical exercises
Practical exercise 3
Practical exercise 5a
Practical exercise 5b