Change Ubuntu hostname on startup based on vCloud Director machine name

hostname.sh

#!/bin/bash
### BEGIN INIT INFO
# Provides:          hostname
# Required-Start:
# Required-Stop:
# Should-Start:      glibc
# X-Start-Before:    networking
# Default-Start:     S
# Default-Stop:
# Short-Description: Sets the hostname based on the vCloud Director OVF details
# Description:       Sets the hostname based on the vCloud Director OVF details
#                    If the hostname cannot be found the current one is untouched
### END INIT INFO

# Adapted from http://www.derekabdine.com/2011/05/setting-vm-name-as-hostname-of-vmware.html

do_start () {

	# First grab the old hostname
	OLDHOSTNAME=`hostname`

	# Now grab the new hostname via VMware RPC (OVF (vCloud Director) specific)
	HOSTNAME=`vmtoolsd --cmd "info-get guestinfo.ovfEnv" | awk -F"\"" ' /vCloud_computerName/ {print $4}'`

	# Sometimes in vCD the Properties section does not exist, so we can't get the machine name
	# Check the new hostname length and bail if necessary
	if [ -z "$HOSTNAME" ]; then
	   echo "Hostname is empty!"
	   exit 1
	fi

	# Check the hostname and bail if necessary
	if [ "$HOSTNAME" == "$OLDHOSTNAME" ]; then
	   echo "Hostname set correctly, nothing to do!"
	   exit 0
	fi

	# Next, set the hostname on the system
	echo -e "Setting hostname to $HOSTNAME...\r\n"
	echo $HOSTNAME > /etc/hostname
	hostname $HOSTNAME

	# Finally, change the hostname in the hosts file
	echo -e "Updating /etc/hosts by replacing $OLDHOSTNAME with $HOSTNAME...\r\n"
	sed -i "s/$OLDHOSTNAME/$HOSTNAME/g" /etc/hosts

}

case "$1" in
  start|"")
	do_start
	;;
  restart|reload|force-reload)
	echo "Error: argument '$1' not supported" >&2
	exit 3
	;;
  stop)
	# No-op
	;;
  *)
	echo "Usage: hostname.sh [start|stop]" >&2
	exit 3
	;;
esac