Linux comand: apt-get

System update

 sudo apt-get update && sudo apt-get upgrade && sudo apt-get dist-upgrade

Package instalation

sudo apt-get install package-name

Search package

sudo apt-cache search qbasic

apt-get (update/install/purge package
apt-cache search

Sources file path

/etc/sources.list lista de repositorios de paquetes

apt-key

Remove expired key

apt-key list
apt-key del <expired key>

Retrive missing keys

To retrieve key ED444FF07D8D0BF6

gpg --keyserver pgpkeys.mit.edu --recv-key  ED444FF07D8D0BF6
gpg -a --export ED444FF07D8D0BF6 | sudo apt-key add -

Using backports

cat /etc/apt/sources.list.d/backports.list

deb http://ftp.debian.org/debian jessie-backports main
sudo apt-get install python-certbot-apache -t jessie-backports

Fix apt-get gone wrong

 sudo apt-get autoremove
 sudo apt-get --purge remove && sudo apt-get autoclean
 sudo apt-get -f install
 sudo apt-get update
 sudo apt-get upgrade && sudo apt-get dist-upgrade
 sudo dpkg --configure -a