當輸入sudo apt-get install vim-gtk時
出現了下面問題：
nigel@yq-ubuntu:~/worksp$ sudo apt-get install vim-gtk
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package vim-gtk 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-gtk' has no installation candidate
解決辦法就是修改軟件源設置
1.備份源文件，cp -i /etc/apt/sources.list /etc/apt/sources.list_backup
2.打開sources.list，root@ubuntu:/etc/apt# gedit sources.list
3.在源文件中加入如下阿裡巴巴的阿裡雲服務器的地址並保存。（當然也可以是其他公司的地址）
deb
http://mirrors.aliyun.com/ubuntu/ trusty main restricted universe multiverse
debhttp://mirrors.aliyun.com/ubuntu/ trusty-security main restricted universe multiverse
debhttp://mirrors.aliyun.com/ubuntu/ trusty-updates main restricted universe multiverse
debhttp://mirrors.aliyun.com/ubuntu/ trusty-proposed main restricted universe multiverse
debhttp://mirrors.aliyun.com/ubuntu/ trusty-backports main restricted universe multiverse
deb-srchttp://mirrors.aliyun.com/ubuntu/ trusty main restricted universe multiverse
deb-srchttp://mirrors.aliyun.com/ubuntu/ trusty-security main restricted universe multiverse
deb-src
http://mirrors.aliyun.com/ubuntu/ trusty-updates main restricted universe multiverse
deb-srchttp://mirrors.aliyun.com/ubuntu/ trusty-proposed main restricted universe multiverse
deb-srchttp://mirrors.aliyun.com/ubuntu/ trusty-backports main restricted universe multiverse
4.更新：apt-get
update
5.更新後，再安裝vim，sudo
apt-get install vim
這樣問題就解決了。
