Find the total size of a folder from the command line — by Marcel Stimberg on Ask Ubuntu

Shows how to make your user own a folder and everything inside it with chown -R, and optionally the group too. It's useful when files created with sudo have become unwritable.

On Ubuntu, members of the sudo group can already use sudo, so you just add the user to that group instead of editing /etc/sudoers. The change takes effect at the user's next login.

Explains how dpkg, apt and the graphical installers relate, and how to install a downloaded .deb package from the terminal, including fixing missing dependencies afterwards.