ubuntu5.1

1、修改sources.list。
$ gedit /etc/apt/sources.list( sudo mv */sources.list /etc/apt/sources.list
)

deb ftp://ftp.sjtu.edu.cn/ubuntu/ dapper main multiverse restricted universe
deb-src ftp://ftp.sjtu.edu.cn/ubuntu/ dapper main multiverse restricted universe
deb ftp://ftp.sjtu.edu.cn/ubuntu/ dapper-backports main multiverse restricted universe
deb-src ftp://ftp.sjtu.edu.cn/ubuntu/ dapper-backports main multiverse restricted universe
deb ftp://ftp.sjtu.edu.cn/ubuntu/ dapper-proposed main multiverse restricted universe
deb-src ftp://ftp.sjtu.edu.cn/ubuntu/ dapper-proposed main multiverse restricted universe
deb ftp://ftp.sjtu.edu.cn/ubuntu/ dapper-security main multiverse restricted universe
deb-src ftp://ftp.sjtu.edu.cn/ubuntu/ dapper-security main multiverse restricted universe
deb ftp://ftp.sjtu.edu.cn/ubuntu/ dapper-updates main multiverse restricted universe
deb-src ftp://ftp.sjtu.edu.cn/ubuntu/ dapper-updates main multiverse restricted universe
deb ftp://ftp.sjtu.edu.cn/ubuntu-cn/ breezy bleeding main multiverse restricted universe

deb ftp://ftp.sjtu.edu.cn/ubuntu/ breezy main multiverse restricted universe
deb-src ftp://ftp.sjtu.edu.cn/ubuntu/ breezy main multiverse restricted universe
deb ftp://ftp.sjtu.edu.cn/ubuntu/ breezy-backports main multiverse restricted universe
deb-src ftp://ftp.sjtu.edu.cn/ubuntu/ breezy-backports main multiverse restricted universe
deb ftp://ftp.sjtu.edu.cn/ubuntu/ breezy-proposed main multiverse restricted universe
deb-src ftp://ftp.sjtu.edu.cn/ubuntu/ breezy-proposed main multiverse restricted universe
deb ftp://ftp.sjtu.edu.cn/ubuntu/ breezy-security main multiverse restricted universe
deb-src ftp://ftp.sjtu.edu.cn/ubuntu/ breezy-security main multiverse restricted universe
deb ftp://ftp.sjtu.edu.cn/ubuntu/ breezy-updates main multiverse restricted universe
deb-src ftp://ftp.sjtu.edu.cn/ubuntu/ breezy-updates main multiverse restricted universe

2、刷新包信息。
$ sudo apt-get update

3、升级
$ sudo apt-get dist-upgrade