给服务器装了个组件，结果 Starting MySQL.Manager of pid-file quit without updating file. Google了一下，说法大概有以下几种：
- 各种权限问题
- /etc/my.cnf 把 skip federated注释掉
- /etc/my.cnf设置数据库路径 datadir = /xxx
- 如果删除了日志文件，也要将mysql-bin.index删除
- 禁用日志 #log-bin=mysql-bin
#binlog_format=mixed
其实这些方法都对，关键是要对症下药，最后才想起看错误日志（主机名.err）：
121018 22:56:14 mysqld_safe mysqld from pid file /usr/local/mysql/var/localhost.pid ended
121018 23:03:12 mysqld_safe Starting mysqld daemon with databases from /usr/local/mysql/var
121018 23:03:12 [ERROR] Can't start server: Bind on TCP/IP port: Address already in use
121018 23:03:12 [ERROR] Do you already have another mysqld server running on port: 3306 ?
121018 23:03:12 [ERROR] Aborting
mysql的默认端口3306被占用了？汗。。。于是
ps -A|grep mysql
root@localhost:/usr/local/mysql/var# ps -A|grep mysql
1606 ? 00:00:00 mysqld_safe
1749 ? 1-23:38:50 mysqld
将两个进程杀掉
kill -9 1749
kill -9 1606
重启服务后系统恢复正常。
太依赖搜索引擎了，往往忘记去看错误日志，反而走了弯路。