Target
/etc/apt/sources.list
16.04
# USTC (University of Science and Technology of Thina)
# xenial is ubuntu 16.04 version
deb xenial main restricted universe multiverse
deb xenial-security main restricted universe multiverse
deb xenial-updates main restricted universe multiverse
deb xenial-proposed main restricted universe multiverse
deb xenial-backports main restricted universe multiverse
deb-src xenial main restricted universe multiverse
deb-src xenial-security main restricted universe multiverse
deb-src xenial-updates main restricted universe multiverse
deb-src xenial-proposed main restricted universe multiverse
deb-src xenial-backports main restricted universe multiverse
18.04
deb bionic main restricted universe multiverse
deb-src bionic main restricted universe multiverse
deb bionic-updates main restricted universe multiverse
deb-src bionic-updates main restricted universe multiverse
deb bionic-backports main restricted universe multiverse
deb-src bionic-backports main restricted universe multiverse
deb bionic-security main restricted universe multiverse
deb-src bionic-security main restricted universe multiverse
deb bionic-proposed main restricted universe multiverse
deb-src bionic-proposed main restricted universe multiverse