Cat command doesnot work

I am trying to launch mira robot in local computer it, shows following error in spwan.launch.
Can you please help me?
why is it so?

my spawn file is this –

<?xml version="1.0" encoding="UTF-8"?>
<arg name="x" default="0.0" />
<arg name="y" default="0.0" />
<arg name="z" default="0.0" />

<arg name="urdf_robot_file" default="" />
<arg name="robot_name" default="" />

<!-- This Version was created due to some errors seen in the V1 that crashed GAzebo or went too slow in spawn -->
<!-- Load the URDF into the ROS Parameter Server -->
<param name="robot_description" command="cat $(arg urdf_robot_file)" />

<!-- Run a python script to the send a service call to gazebo_ros to spawn a URDF robot -->
<node name="urdf_spawner" pkg="gazebo_ros" type="spawn_model" respawn="false" output="screen"
args="-urdf -x $(arg x) -y $(arg y) -z $(arg z)  -model $(arg robot_name) -param robot_description"/>

Hello @more.1787364,

The error says that the file is not in the specified path: /home/harshal/catkin_ws/src/my_mira_description/urdf/mira_simple_collisions_inertias.urdf. Make sure that the file is there and you can reach it from your shell.