ROS network setup depending on route to MASTER

ros-network.sh

#!bin/bash

# This script configures the ROS environment variables according to the route
# to the ROS_MASTER. ROS_MASTER can either be defined as an evironment variable
# itself or given as first argument to this script. The ROS_IP and ROS_HOSTNAME
# are set according to the IP that is sitting on the route to this master. 
# The ROS_MASTER_URI is also set, using port 11311. ROS_MASTER needs to be defined
# as a numeric IP address, not a hostname.

if [ "$1" ]; then
	ROS_MASTER="$1"
fi

if [ -z "$ROS_MASTER" ]; then
	ROS_MASTER=127.0.0.1
fi

echo "ROS_MASTER:     $ROS_MASTER"

export ROS_IP=`ip route get $ROS_MASTER | grep "src" | sed 's/.*src \([0-9\.]*\).*/\1/'`
export ROS_HOSTNAME=$ROS_IP
export ROS_MASTER_URI="http://$ROS_MASTER:11311/"

echo "ROS_IP:         $ROS_IP"
echo "ROS_HOSTNAME:   $ROS_HOSTNAME"
echo "ROS_MASTER_URI: $ROS_MASTER_URI"