play_bag.launch

<launch>
  <arg name="robot_name" default="" />
  <arg name="bag" />
  <arg name="rate" default="1" />

  <arg name="fullpath" value="$(eval eval('_' + '_import_' + '_(\'os\').path.abspath(arg(\'bag\'))') )" />
  <param name="use_sim_time" value="true" />
  <node pkg="rosbag"
        type="play"
        name="bag"
        args="-r $(arg rate) --clock '$(arg fullpath)'"
        output="screen" />
</launch>