I was working on entirely a different problem of trying to publish into cmd_vel from move_base and a custom node of mine. Basically, movebase issues twist messages to drive my robot from one pose to another. And, I was attempting to issue another set of twist messages to get my robot to follow a wall to the destination. My intention was to do this by issuing twists with just twist.angular.z = 0.5 values until to robot was a set distance from the wall. So, these two nodes should have been publishing to **cmdvel** and moving the robot along.

BUT, what i found was that my node seemed to premept movebase. The robot would not respond to movebase unless I stopped my node.

SO, I decided to experiment with the mux package and I cloned it into my catkin_ws/src directory. However, when I tried launching my launch file, I got the following error:

.
.
process[master]: started with pid [7849]
Traceback (most recent call last):
  File "/home/sisko/catkin_ws/devel/bin/rosmaster", line 15, in <module>
    exec(compile(fh.read(), python_script, 'exec'), context)
  File "/home/sisko/catkin_ws/src/ros_comm/tools/rosmaster/scripts/rosmaster", line 35, in <module>
    rosmaster.rosmaster_main()
  File "/home/sisko/catkin_ws/src/ros_comm/tools/rosmaster/src/rosmaster/main.py", line 84, in rosmaster_main
    configure_logging()   
  File "/home/sisko/catkin_ws/src/ros_comm/tools/rosmaster/src/rosmaster/main.py", line 58, in configure_logging
    _log_filename = rosgraph.roslogging.configure_logging('rosmaster', logging.DEBUG, filename=filename)
  File "/home/sisko/catkin_ws/src/ros_comm/tools/rosgraph/src/rosgraph/roslogging.py", line 192, in configure_logging
    logging.config.fileConfig(config_file, disable_existing_loggers=False)
  File "/usr/lib/python2.7/logging/config.py", line 85, in fileConfig
    handlers = _install_handlers(cp, formatters)
  File "/usr/lib/python2.7/logging/config.py", line 163, in _install_handlers
    h = klass(*args)
  File "/home/sisko/catkin_ws/src/ros_comm/tools/rosgraph/src/rosgraph/roslogging.py", line 237, in __init__
    from rospy.rostime import get_time, is_wallclock
  File "/home/sisko/catkin_ws/devel/lib/python2.7/dist-packages/rospy/__init__.py", line 34, in <module>
    exec(__fh.read())
  File "<string>", line 49, in <module>
  File "/home/sisko/catkin_ws/src/ros_comm/clients/rospy/src/rospy/client.py", line 60, in <module>
    import rospy.impl.init
  File "/home/sisko/catkin_ws/src/ros_comm/clients/rospy/src/rospy/impl/init.py", line 54, in <module>
    from .tcpros import init_tcpros
  File "/home/sisko/catkin_ws/src/ros_comm/clients/rospy/src/rospy/impl/tcpros.py", line 45, in <module>
    import rospy.impl.tcpros_service
  File "/home/sisko/catkin_ws/src/ros_comm/clients/rospy/src/rospy/impl/tcpros_service.py", line 54, in <module>
    from rospy.impl.tcpros_base import TCPROSTransport, TCPROSTransportProtocol, \
  File "/home/sisko/catkin_ws/src/ros_comm/clients/rospy/src/rospy/impl/tcpros_base.py", line 160
    (e_errno, msg, *_) = e.args
                   ^
SyntaxError: invalid syntax
================================================================================REQUIRED process [master] has died!
process has died [pid 7849, exit code 1, cmd rosmaster --core -p 11311 -w 3 __log:=/home/sisko/.ros/log/9f569ecc-a37c-11eb-b1b2-70188b82a32f/master.log].
log file: /home/sisko/.ros/log/9f569ecc-a37c-11eb-b1b2-70188b82a32f/master*.log
Initiating shutdown!
================================================================================
[master] killing on exit
RLException: ERROR: could not contact master [http://Razer-Blade:11311/]
The traceback for the exception was written to the log file
No handlers could be found for logger "roslaunch"

I tried executing catkin-make in my catkin_ws directory and I get the following :

-- Using these message generators: gencpp;geneus;genlisp;gennodejs;genpy
-- Generating .msg files for action actions_tutorial/WashTheDishes /home/sisko/catkin_ws/src/actions_tutorial/action/WashTheDishes.action
-- actions_tutorial: 7 messages, 0 services
-- +++ processing catkin package: 'hector_geotiff'
-- ==> add_subdirectory(hector_slam/hector_geotiff)
-- Using these message generators: gencpp;geneus;genlisp;gennodejs;genpy
CMake Error at /home/sisko/catkin_ws/devel/share/roscpp/cmake/roscppConfig.cmake:113 (message):
  Project 'roscpp' specifies
  '/home/sisko/catkin_ws/src/ros_comm/clients/roscpp/include' as an include
  dir, which is not found.  It does neither exist as an absolute directory
  nor in
  '/home/sisko/catkin_ws/src/ros_comm/clients/roscpp//home/sisko/catkin_ws/src/ros_comm/clients/roscpp/include'.
  Check the website 'http://ros.org/wiki/roscpp' for information and consider
  reporting the problem.
Call Stack (most recent call first):
  /opt/ros/melodic/share/catkin/cmake/catkinConfig.cmake:76 (find_package)
  hector_slam/hector_geotiff/CMakeLists.txt:5 (find_package)


-- Configuring incomplete, errors occurred!
See also "/home/sisko/catkin_ws/build/CMakeFiles/CMakeOutput.log".
See also "/home/sisko/catkin_ws/build/CMakeFiles/CMakeError.log".
Makefile:22030: recipe for target 'cmake_check_build_system' failed
make: *** [cmake_check_build_system] Error 1
Invoking "make cmake_check_build_system" failed

It seems ros-comm was installed by default and cloning it in and compiling it seemed to have messed up my environment. I have tried multiple attempts to fix this like sudo apt-get remove --purge ros-melodic-ros-comm and deleting the cloned copy in my catkin_ws/src directory but my launch files still fail to start.

Any help, PLEASE !!!