在后台运行python脚本-Raspbian

Question

I have recently constructed a small robot car using my raspberry pi 3 with raspbian stretch. I am currently at the point where I can drive the car around using an xbox360 controller plugged into the pi USB port. My issue is that I do not like having to ssh into the pi and run the script I have written in order to use the robot (robot.py).

What I would like to do is have a script running in the background which works something like this:

#while true
    #if joystick is detected
        #robotoffflag=true
        #if startup button is pressed on the joystick && robotoffflag
            #robotoffflag=false
            #run robot.py to control the robot
            #robot.py already has controls for shutting down the robot
            #which disables the motors and sets robotoffflag to true

This way, if my pi is powered up, I can at any point just press a button on my controller and start using the robot. Then when I am done, press another button on the controller to disable the robot.

My question is, am I going about this in the right way? Having a script running in the background which is basically an infinite loop with conditionals inside seems silly to me. Would it be better to have something more event driven?

Answer 1

Here is something I might do, thought a bit of a hack. Put the python code in to a loop, adding a very short sleep at the end of each loop to limit cpu usage. Then run the python script inside a session of tmux, detached of course. The python script will then run until the tmux session is killed, even if your ssh session exits. tmux is just an example utility, by the way. There are others. Of course you could get fancy and implement the loop within a signal-and-wait mechanism, which would wait for a signal from your controller, then launch that from an operating system daemon. Depends how deep you want to go ...