Linux下安装MySQL出现“ls: /var/lib/mysql/*.pid: 没有那个文件

warning: MySQL-server-5.5.28-1.linux2.6.i386.rpm: V3 DSA signature: NOKEY, key ID 5072e1f5
Preparing...                                                            ########################################### [100%]
You have more than one PID file:
ls: /var/lib/mysql/*.pid: 没有那个文件或目录
Please check which one (if any) corresponds to a running server
and delete all others before repeating the MySQL upgrade.
error: %pre(MySQL-server-5.5.28-1.linux2.6) scriptlet failed, exit status 1
error:   install: %pre scriptlet failed (2), skipping MySQL-server-5.5.28-1.linux2.6