Mininet: Cannot find required executable controller 問題解決方法

當我運作mininet時，出現以下問題：

***creating network ***adding controller ***adding hosts: h1 h2 h3 h4 h5 ***adding switches: s1 ***adding links: (h1, s1) (h2, s1) (h3, s1) (h4, s1) (h5, s1) ***configuring hosts ***starting controller cannot find required executable controller. please make sure that it is installed and available in your $path: (/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin)

運作以下指令：

sudo ln /usr/bin/ovs-controller /usr/bin/controller

即可解決。