& ldquo; Кандидат без установки & rdquo; при попытке установить build-essential

apt-get install build-essential завершается ошибкой со следующими ошибками:

~$ sudo apt-get install build-essential
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Package build-essential is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

E: Package 'build-essential' has no installation candidate

Я только что запустил sudo apt-get update перед попыткой установки.

Папка /etc/apt/sources.list.d пуста. Вот что такое /etc/apt/sources.list:

$ grep deb\ http: /etc/apt/sources.list  #(with "deb http://" deleted)  
us.archive.ubuntu.com/ubuntu/ raring main restricted  
us.archive.ubuntu.com/ubuntu/ raring-updates main restricted  
us.archive.ubuntu.com/ubuntu/ raring universe  
us.archive.ubuntu.com/ubuntu/ raring-updates universe  
us.archive.ubuntu.com/ubuntu/ raring multiverse  
us.archive.ubuntu.com/ubuntu/ raring-updates multiverse  
us.archive.ubuntu.com/ubuntu/ raring-backports main restricted universe multiverse  
security.ubuntu.com/ubuntu raring-security main restricted  
security.ubuntu.com/ubuntu raring-security universe  
security.ubuntu.com/ubuntu raring-security multiverse  
extras.ubuntu.com/ubuntu raring main  

Это с Ubuntu 13.04 64 бит.

apt-cache policy build-essential 
build-essential:
 Installed: (none)
 Candidate: (none)
 Version table: 

Каталог /etc/apt/sources.list.d пуст.