upgrade ubuntu 12.04 to 13.04

貌似昨天发布了Ubuntu 13.04,也不管现有的12.04 LTS是一个长期支持版本了，升级看看,对于伪linux粉丝，当然不用升级管理器，直接修改sources.list,终端界面升级咯

sudo sed -i 's/precise/raring/' /etc/apt/sources.list
sudo apt-get update
sudo apt-get dist-upgrade

中途遭遇一次GPG公锁错误
W: A error occurred during the signature verification.
The repository is not updated and the previous index files will be used. GPG error:http://extras.ubuntu.com quantal Release:
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 16126D3A3E5C1192
解决方法如下

apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 16126D3A3E5C1192