KVM : add a device with virsh attach-device

small tips.

prepare an xml file

$ cat network-add.xml

<interface type='network'>

  <source network='net-192.168.42'/>

  <model type='virtio'/>

</interface>

$ virsh dumpxml m-node03 | grep network

    <interface type='network'>

      <source network='net-192.168.40'/>

    <interface type='network'>

      <source network='net-192.168.41'/>

$

$ virsh attach-device m-node03 network-add.xml --config

Device attached successfully

$

$ virsh dumpxml m-node03 | grep network

    <interface type='network'>

      <source network='net-192.168.40'/>

    <interface type='network'>

      <source network='net-192.168.41'/>

    <interface type='network'>

      <source network='net-192.168.42'/>

$