root@clachan:~# apt update
Hit:1 http://us.archive.ubuntu.com/ubuntu xenial InRelease
Hit:2 http://us.archive.ubuntu.com/ubuntu xenial-updates InRelease
Ign:3 http://dl.google.com/linux/chrome/deb stable InRelease
Hit:4 http://us.archive.ubuntu.com/ubuntu xenial-backports InRelease
Hit:5 http://dl.google.com/linux/chrome/deb stable Release
Get:6 http://security.ubuntu.com/ubuntu xenial-security InRelease [94.5 kB]
Hit:8 https://deb.opera.com/opera-stable stable InRelease
Fetched 94.5 kB in 1s (84.0 kB/s)
Reading package lists... Done
Building dependency tree
Reading state information... Done
All packages are up to date.
root@clachan:~# aptitude update
Hit http://us.archive.ubuntu.com/ubuntu xenial InRelease
Ign http://dl.google.com/linux/chrome/deb stable InRelease
Hit http://us.archive.ubuntu.com/ubuntu xenial-updates InRelease
Hit http://dl.google.com/linux/chrome/deb stable Release
Get: 1 http://security.ubuntu.com/ubuntu xenial-security InRelease [94.5 kB]
Hit http://us.archive.ubuntu.com/ubuntu xenial-backports InRelease
Hit https://deb.opera.com/opera-stable stable InRelease
Fetched 94.5 kB in 0s (101 kB/s)
root@clachan:~# cat /etc/apt/sources.list
deb http://us.archive.ubuntu.com/ubuntu/ xenial main restricted
deb http://us.archive.ubuntu.com/ubuntu/ xenial-updates main restricted
deb http://us.archive.ubuntu.com/ubuntu/ xenial universe
deb http://us.archive.ubuntu.com/ubuntu/ xenial-updates universe
deb http://us.archive.ubuntu.com/ubuntu/ xenial multiverse
deb http://us.archive.ubuntu.com/ubuntu/ xenial-updates multiverse
deb http://us.archive.ubuntu.com/ubuntu/ xenial-backports main restricted universe multiverse
## deb http://archive.canonical.com/ubuntu xenial partner
deb http://security.ubuntu.com/ubuntu xenial-security main restricted
deb http://security.ubuntu.com/ubuntu xenial-security universe
deb http://security.ubuntu.com/ubuntu xenial-security multiverse