Give a user sudo (administrator) rights on Ubuntu — by ændrük 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.

du -hs gives a single human-readable total for a folder. The answer explains the -h (human-readable) and -s (summary) flags and how to sort folder sizes.

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.