sudo vim /etc/apt/sources.list deb http://ftp.cuhk.edu.hk/pub/Linux/ubuntu/xenial main restricted deb http://ftp.cuhk.edu.hk/pub/Linux/ubuntu/xenial-updates main restricted deb http://ftp.cuhk.edu.hk/pub/Linux/ubuntu/xenial universe deb http://ftp.cuhk.edu.hk/pub/Linux/ubuntu/xenial-updates universe deb http://ftp.cuhk.edu.hk/pub/Linux/ubuntu/xenial multiverse deb http://ftp.cuhk.edu.hk/pub/Linux/ubuntu/xenial-updates multiverse deb http://ftp.cuhk.edu.hk/pub/Linux/ubuntu/xenial-backports main restricted universe multiverse deb http://ftp.cuhk.edu.hk/pub/Linux/ubuntu/xenial-security main restricted deb http://ftp.cuhk.edu.hk/pub/Linux/ubuntu/xenial-security universe deb http://ftp.cuhk.edu.hk/pub/Linux/ubuntu/xenial-security multiverse ...