added /etc/network/interfaces generator initial version

#!/usr/bin/env python

from __future__ import division

from __future__ import print_function

'''

/**

 * @file generate_default_network_interfaces.py

 * @brief - Generate the default /etc/network/interfaces file

 *          based on the Elphel's Poky config: poky/build/conf/local.conf

 *          which contains ip address (and network mask)

 *        - Install into rootfs

 * @copyright Copyright (C) 2018 Elphel Inc.

 * @author Oleg Dzhimiev <oleg@elphel.com>

 * @deffield updated: unknown

 *

 * @par <b>License</b>:

 *  This program is free software: you can redistribute it and/or modify

 *  it under the terms of the GNU General Public License as published by

 *  the Free Software Foundation, either version 3 of the License, or

 *  (at your option) any later version.

 *

 *  This program is distributed in the hope that it will be useful,

 *  but WITHOUT ANY WARRANTY; without even the implied warranty of

 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 *  GNU General Public License for more details.

 *

 *  You should have received a copy of the GNU General Public License

 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.

*/

'''

__copyright__ = "Copyright (C) 2018 Elphel, Inc."

__license__ = "GPL-3.0+"

__maintainer__ = "Oleg Dzhimiev"

__email__ = "oleg@elphel.com"

import os

path = "generated"

filepath = os.path.join(path,"interfaces")

# in python 3 it's a single line:

#     os.makedirs(path, exist_ok=True)

try:

  os.makedirs(path)

except OSError:

  if not os.path.isdir(path):

    raise

ip      = "192.168.0.9"

mask    = "255.255.255.0"

gateway = "192.168.0.15"

with open(filepath,"w") as f:

    f.write("""\

# This is an auto-generated file created by a script that is run from

# Elphel's Yocto Poky framework setup.

#

# See

#   project: https://git.elphel.com/Elphel/elphel-init

#   file   : src/generate_default_network_interfaces.py

#

# /etc/network/interfaces -- configuration file for ifup(8), ifdown(8)

auto lo

iface lo inet loopback

auto eth0

iface eth0 inet static

    address {0}

    netmask {1}

    gateway {2}

""".format(ip,mask,gateway))