How to pass arguments to ros launch file from bash script and how to create ros launch file running python script with those parser arguments

I have a python script which runs as follows:

rosrun camera_calibrator cameracalibrator.py --size 12x8 --square 0.05 image:=/topic_name

I have launch file are follows:

<launch>
  <node name="image_pub_sub_node" pkg="image_pub" type="image_pub_sub" output="screen"/>
  <node name="cameracalibrator_node" pkg="camera_calibration" type="cameracalibrator.py" output="screen"/>
</launch>

Bash script as:

#!/bin/sh
foldername=camera_calibration_$(date +"%m-%d-%Y")
roslaunch image_pub cam_calibrator.launch $foldername

I want to pass this foldername in bash to roslaunch file (cam_calibrator.launch) as above, then get that folder-name as argument and send that to my python script “cameracalibrator.py” just like –size, –square and image:=/topic_name arguments as well to the image_pub_sub c++ script.

Also how to send those size and square arguments to python script in launch file?

Can anyone let me now please?

Answer

The roslaunch command line accept arguments, so yes it is possible to do this.

In your launch file, you must declare the arguments like this :

<launch>
    <arg name="foldername"      default="whatever_you_want" />
</launch>

Then, you want to check the list of parameters supported by the nodes that you are using. Typically, I see that you are using the node cameracalibrator.py. If this node is well written, it defines to ROS the parameters that it uses, like image (which I am assuming is a ROS topic name). Once you know which parameter your node needs, you can provide it to ROS in your launch file like this:

(in this case, I am using the image parameter since it is the only one from your question where I am sure it is a normal ROS parameter)

<launch>
    <!-- list of arguments that can be given as inputs of the launch file -->
    <arg name="foldername"      default="whatever_you_want" />
    <arg name="image_name"      default="whatever_you_want" />

    <node name="cameracalibrator_node" pkg="camera_calibration" type="cameracalibrator.py" output="screen">

        <!-- list of all parameters to pass to the node -->
        <param name="image"   type="string" value="$(arg image_name)" />

    </node>

</launch>

Once you have such a ros launch file, you can call it with:

#!/usr/bin/env bash
roslaunch image_pub cam_calibrator.launch foldername :=foldername image_name:=$YOUR_IMAGE_NAME

PS: it is recommended to use #!/usr/bin/env bash (or sh) instead of #!/bin/sh