Linux: Apt Proxy Add/Remove
Source:https://stackoverflow.com/questions/38591415/ubuntu-16-04-apt-get-not-working-through-proxy
check /etc/apt/apt.conf
add/ remove Aquire::<protocol> as needed
/etc/apt/apt.conf
Acquire::http::proxy "http://[username]:[password]@[webproxy]:[port]/";
Acquire::https::proxy "https://[username]:[password]@[webproxy]:[port]/";
Acquire::ftp::proxy "ftp://[username]:[password]@[webproxy]:[port]/";
Acquire::socks::proxy "socks://[username]:[password]@[webproxy]:[port]/";
In Ubuntu 14.04, in order to use some commands in terminal (like apt-get) trough the company proxy, I need to do the following changes, beyond System Settings > Network > Network proxy > "Apply system wide" (shame on you, Ubuntu)