ubutnu 12.04 到14.04的升级

有一个主力服务器，安装的ubuntu 12.04 server版，今天14.04版本发布了，因此就想把系统给升级了，但升级的时候：

sudo do-release-upgrade
Checking for a new Ubuntu release
No new release found

感到奇怪，搜索了一下，在https://news.ycombinator.com/item?id=7604177中有一个回复提到了：

It is by design!

Upgrades between LTS releases are not enabled by default until the first point release, 14.04.1, scheduled for July. It is recommended that most LTS users wait until then before upgrading to 14.04. You could add a ‘-d’ flag if you’re in a hurry!

原来是LTS版本设计为要到14.04.1才会提示升级。当然着急升级的话，也可以：

sudo do-release-upgrade -d