Confusion regarding 'arg' heirarchy in launch files

edit

I have a launch file named launch_one.launch. It looks like this -

<?xml version="1.0" encoding="UTF-8"?>

<launch> 

    <include file="$(find husky_description)/launch/description.launch" >
        <arg name="laser_enabled" default="$(optenv laser_enabled 1)"/>
        <arg name="realsense_enabled" default="$(optenv realsense_enabled)"/>
        <arg name="urdf_extras" default="$(optenv urdf_extras)"/>
    </include>

    <node name="robot_state_publisher" pkg="robot_state_publisher" type="robot_state_publisher" />  

</launch>

The description.launch file look like this -

<launch>

  <arg name="robot_namespace" default="/"/>
  <arg name="laser_enabled" default="$(optenv HUSKY_LMS1XX_ENABLED false)"/>
  <arg name="realsense_enabled" default="$(optenv HUSKY_REALSENSE_ENABLED false)"/>
  <arg name="urdf_extras" default="$(optenv HUSKY_URDF_EXTRAS)"/>

  <param name="robot_description" command="$(find xacro)/xacro '$(find husky_description)/urdf/husky.urdf.xacro'
    robot_namespace:=$(arg robot_namespace)
    laser_enabled:=$(arg laser_enabled)
    realsense_enabled:=$(arg realsense_enabled)
    urdf_extras:=$(arg urdf_extras)
    " />

</launch>

Assumption - There are no environment variables named laser_enabled and HUSKY_LMS1XX_ENABLED in my system.

I run roslaunch launch_one.launch in a new terminal window. I have 2 queries -

• Which of the two launch files (launch_one.launch or description.launch) would dictate the final value of the arg laser_enabled in the shell environment? Would it be equal to 1 (as dictated by launch_one.launch) or would it be equal to 0 (as dictated by description.launch) ?

• How can I check the value of the arg laser_enabled through the terminal? I know that I can do that by running the command printenv. However, I can't take that route because the terminal window is already occupied by the currently running roslaunch file. I tried to open a new tab in the same terminal window and ran the command printenv. It didn't return any variable named laser_enabled.