Demo script to set arp notify after restoration of network link

enable_arp_notify.sh

#!/bin/bash
#
# This script ensures that the correct sysctl is configured on the
# installed guest.  This is needed to fix case 20602.
# Reboot the guest regardless of whether we take any action here.

GARP_ENABLE="net.ipv4.conf.default.arp_notify = 1"
SYSCTL_FILE="/etc/sysctl.conf"

if [ -e $SYSCTL_FILE ]
then
  grep -q "$GARP_ENABLE" $SYSCTL_FILE
  if [ $? != 0 ]
  then
    echo stuffing $GARP_ENABLE into $SYSCTL_FILE
    echo >> $SYSCTL_FILE
    echo "# Configure to send gARP after migration" >> $SYSCTL_FILE
    echo "$GARP_ENABLE" >> $SYSCTL_FILE
  else
    echo $GARP_ENABLE already found in $SYSCTL_FILE
    sysctl -a | grep -q "$GARP_ENABLE"
    if [ $? != 0 ]
    then
      echo sysctl is not working - "$GARP_ENABLE" not found
    fi
  fi
else
  echo system does not have $SYSCTL_FILE -- nothing to do
fi
echo rebooting now
shutdown -r now

The reboot should really prompt the user first and allow him to decline to reboot now.

I'm going to modify this to take a --reboot argument (which automated test will supply) so that it operates as expected when run by test. In interactive (default) mode, it'll prompt every step of the way.