Run second ROS, Gazebo, and gzweb instances on a single computer.

second-ros.sh

# run a secondary ROS and Gazebo instance
#
# when starting ROS master, the new port needs to be specified:
#   roscore -p $ROS_PORT
#
# gzweb does not require any environment variables, but the port must be
# specified when gzweb is started:
#   npm start -p $GZWEB_PORT
#
# Gazebo does not require any special options when run

# default ROS master port is 11311
export ROS_PORT="11312"
export ROS_MASTER_URI="http://localhost:$ROS_PORT"

# default Gazebo port is 11345
export GAZEBO_PORT="11346"
export GAZEBO_MASTER_URI="http://localhost:$GAZEBO_PORT"

# default
export GZWEB_PORT="8081"