ioctl(TUNSETIFF): Device or resource busy

ip tuntap add test_tun mode tap user root
ioctl(TUNSETIFF): Device or resource busy

#!/bin/sh
set -x

switch=virbr0 

if [ -n "$1" ];then
    ip tuntap add $1 mode tap user `whoami`
    ip link set $1 up
    sleep 0.5s
    ip link set $1 master $switch
    exit 0
else
    echo "Error: no interface specified"
    exit 1
fi

原来是test_tun已经存在了

 ip link del test_tun