我跑lsb_release -a
输出：
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 12.04.4 LTS
Release: 12.04
Codename: precise
我跑： nano /etc/apt/sources.list
输出：
deb mirror://mirrors.ubuntu.com/mirrors.txt precise main universe
deb mirror://mirrors.ubuntu.com/mirrors.txt precise main-updates universe multiverse
deb mirror://mirrors.ubuntu.com/mirrors.txt precise main-backports universe multiverse
deb mirror://mirrors.ubuntu.com/mirrors.txt precise main-security universe multiverse
我跑sudo apt-get update
输出：
Hit http://ftp.oleane.net/ubuntu/ precise Release.gpg
Hit http://ftp.oleane.net/ubuntu/ precise Release
Hit http://ftp.oleane.net/ubuntu/ precise/main i386 Packages
Hit http://ftp.oleane.net/ubuntu/ precise/universe i386 Packages
W: Failed to fetch mirror://mirrors.ubuntu.com/mirrors.txt/dists/precise/Release Unable to find expected entry 'main-updates/binary-i386/Packages' in Release file (Wrong sources.list entry or malformed file)
E: Some index files failed to download. They have been ignored, or old ones used instead.
答案1
你应该有：
deb mirror://mirrors.ubuntu.com/mirrors.txt precise main restricted universe multiverse
deb mirror://mirrors.ubuntu.com/mirrors.txt precise-updates main restricted universe multiverse
deb mirror://mirrors.ubuntu.com/mirrors.txt precise-backports main restricted universe multiverse
deb mirror://mirrors.ubuntu.com/mirrors.txt precise-security main restricted universe multiverse
升级您的/etc/apt/sources.list文件。