Hi,<br><br>I&#39;m working on a different solution to the issue of mapping ports to sensors.  Instead of configuring every computer to automatically map usb devices to specific addresses,  I wrote a program that uses the libudev library (also get ID for hokuyos) to find the serial number of the device, so I can query for a serial number and get back the device it is plugged into (or determine that it is not there)<br>
The motivation for doing this:<br>- I swap out devices a bit, and configuring the udev is more annoying than just changing a parameter <br>- I can run the same program with the devices plugged into a different computer without having to configure udev.<br>
<br>The problem I am having is in setting the correct parameter to the correct port.<br>What I would like to do is dynamically substitute in the appropriate parameter when running the launch file:<br>&lt;node name=&quot;hokuyo&quot; pkg=&quot;hokuyo_node&quot; type=&quot;hokuyo_node&quot; respawn=&quot;true&quot; output=&quot;screen&quot;&gt;<br>
    &lt;param name=&quot;port&quot; type=&quot;string&quot; value=&quot;$(devfind H0902062)&quot;/&gt;<br> &lt;/node&gt;    <br><br>I see that there is some support for executing functions in the launch file:<br><a href="http://www.ros.org/wiki/roslaunch/XML#substitution_args">http://www.ros.org/wiki/roslaunch/XML#substitution_args</a><br>
Would it be possible to add the running of shell commands?<br><br>Thanks<br>Garratt<br><br>