I learned that in Ubuntu, to restart Unity and get back all the widgets (a bug that happens from time to time removes some widgets from your panel), you can restart unity by doing:
I learned that in Ubuntu, in those cases where launchpad repositories cannot be resolved when doing an update, the reason might be because of missing settings when setting the repositories.
So instead of doing:
sudo add-apt-repository ppa:<REPO_NAME>/ppa
An easy fix is to add the repository adding your current environment variables like:
sudo -E add-apt-repository ppa:<REPO_NAME>/ppa