Khi cài Vim trên Ubuntu 12.04 sử dụng câu lệnh:

$ sudo apt install vim

Thì mình gặp phải lỗi:

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Package vim 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 'vim' has no installation candidate

Làm sao để fix lỗi này vậy mọi người?