Debian Package Manager HOWTO  
Upgrading Packages
To upgrade packages, first update the database:
sudo apt-get update
Then, upgrade the packages as follows:
sudo apt-get upgrade
Some packages may not get automatically upgraded this way (Linux kernel or chrome-remote-desktop for instance). If this occurs, upgrade them as follows:
sudo apt-get --with-new-pkgs upgrade
Resetting Google Keys
When doing apt-get update and having google packages installed (google earth, chrome, chrome-remote-desktop, etc), you may sometimes get some error of the sort:
W: GPG error: stable Release: The following signatures were invalid: KEYEXPIRED D38B4796  KEYEXPIRED 7FAC5991
This can be fixed by deleting the keys and reinstalling them:
sudo apt-key del D38B4796
sudo apt-key del 7FAC5991
wget -q -O - | sudo apt-key add -
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