def delete_net_dev(dev):
    """Delete a network device only if it exists."""
    if device_exists(dev):
        try:
            processutils.execute('ip', 'link', 'delete', dev,
                                 check_exit_code=[0, 2, 254],
                                 run_as_root=True)
            LOG.debug("Net device removed: '%s'", dev)
        except processutils.ProcessExecutionError:
            with excutils.save_and_reraise_exception():
                LOG.error(_LE("Failed removing net device: '%s'"), dev)
def _ovs_vsctl(args, timeout=timeout):
    full_args = ['ovs-vsctl', '--timeout=%s' % timeout] + args
    try:
        return processutils.execute(*full_args, run_as_root=True)
    except Exception as e:
        LOG.error(_LE("Unable to execute %(cmd)s. Exception: %(exception)s"),
                  {'cmd': full_args, 'exception': e})
        raise exception.AgentError(method=full_args)
def _set_device_mtu(dev, mtu):
    """Set the device MTU."""
    processutils.execute('ip', 'link', 'set', dev, 'mtu', mtu,
                         check_exit_code=[0, 2, 254])