freeradius 安装出错的解决办法

sudo apt-get install freeradius-mysql

Selecting previously unselected package freeradius-mysql.
(Reading database ...  files and directories currently installed.)
Preparing to unpack .../freeradius-mysql_2.1.12+dfsg-.2ubuntu8_amd64.deb ...
Unpacking freeradius-mysql (2.1.+dfsg-.2ubuntu8) ...
Setting up freeradius-mysql (2.1.+dfsg-.2ubuntu8) ...
reload: Unknown instance:
invoke-rc.d: initscript freeradius, action "force-reload" failed.
dpkg: error processing package freeradius-mysql (--configure):
 subprocess installed post-installation script returned error exit status
Errors were encountered while processing:
 freeradius-mysql
E: Sub-process /usr/bin/dpkg returned an error code ()

解决办法，先启动，再安装

sudo service freeradius start
freeradius start/running, process 

sudo apt-get install freeradius-mysql
Reading package lists... Done
Building dependency tree
Reading state information... Done
freeradius-mysql is already the newest version.
 upgraded,  newly installed,  to remove and  not upgraded.
 not fully installed or removed.
After this operation,  B of additional disk space will be used.
Do you want to continue? [Y/n] y
Setting up freeradius-mysql (2.1.+dfsg-.2ubuntu8) ...