https://blog.offline-net.com/2011/08/19/ubuntu-long-term-supportlts-8-04-%e3%81%8b%e3%82%89%e9%80%9a%e5%b8%b8%e3%83%aa%e3%83%aa%e3%83%bc%e3%82%b9%e7%89%88%e3%81%b8%e3%82%a2%e3%83%83%e3%83%97%e3%82%b0%e3%83%ac%e3%83%bc%e3%83%89%e3%81%a7/