I am trying to install Gazebo 8.0 simulator for Ubuntu 16.04. I tried the .deb package which gave me this bash script :

gazebo8_install.sh :

# Description:

# This script installs gazebo onto an Ubuntu system.



codename=`lsb_release -sc`



# Make sure we are running a valid Ubuntu distribution

case $codename in

  "xenial" | "yakkety" )

  ;;

  *)

    echo "This script will only work on Ubuntu xenial, and yakkety"

    exit 0

esac



# Add the OSRF repository

if [ ! -e /etc/apt/sources.list.d/gazebo-latest.list ]; then

  sudo sh -c "echo "deb http://packages.osrfoundation.org/gazebo/ubuntu ${codename} main" > /etc/apt/sources.list.d/gazebo-latest.list"

fi



# Download the OSRF keys

has_key=`apt-key list | grep "OSRF deb-builder"`



echo "Downloading keys"

if [ -z "$has_key" ]; then

  wget --quiet http://packages.osrfoundation.org/gazebo.key -O - | sudo apt-key add -

fi





# Update apt

echo "Retrieving packages"

sudo apt-get update -qq

echo "OK"



# Install gazebo

echo "Installing Gazebo"

sudo apt-get install gazebo8 libgazebo8-dev



echo "Complete."

echo "Type gazebo to start the simulator."

I ran it on Terminal with this output :

Downloading keys

OK

Retrieving packages

OK

Installing Gazebo

Reading package lists... Done

Building dependency tree       

Reading state information... Done

Some packages could not be installed. This may mean that you have

requested an impossible situation or if you are using the unstable

distribution that some required packages have not yet been created

or been moved out of Incoming.

The following information may help to resolve the situation:



The following packages have unmet dependencies:

 gazebo8 : Depends: libgazebo8 (= 8.0.0-1~xenial) but it is not going to be installed

           Depends: libsdformat5 but it is not going to be installed

           Recommends: gazebo8-plugin-base

 libgazebo8-dev : Depends: libsdformat5-dev but it is not going to be installed

                  Depends: libignition-math3-dev (> 3.0.0-1) but it is not going to be installed

                  Depends: libignition-transport3-dev (> 3.0.1-1) but it is not going to be installed

                  Depends: libignition-msgs-dev (>= 0.6.999) but it is not going to be installed

                  Depends: libgazebo8 (= 8.0.0-1~xenial) but it is not going to be installed

                  Depends: gazebo8-plugin-base (= 8.0.0-1~xenial)

E: Unable to correct problems, you have held broken packages.

Complete.

Type gazebo to start the simulator.

It says I have held broken packages. But the command apt-mark showhold returns empty. I tried to run Gazebo but it starts gazebo7.0 not 8.0. What is the problem here & how do I solve it?