Linux:Unable to locate package

原文链接：http://www.songyawei.cn/content/2918

在设置了软件的源后， sudo apt-get install，出现Unable to locate package错误，如：

1. letuknowit@ubuntu:~$ sudo apt-get install mysql-server mysql-client
2. [sudo] password for letuknowit:
3. Reading package lists… Done
4. Building dependency tree
5. Reading state information… Done
6. E: Unable to locate package mysql-server
7. E: Unable to locate package mysql-client
8. letuknowit@ubuntu:~$

应该先：

1. sudo apt-get update

原文链接：http://www.songyawei.cn/content/2918