Shell – Using a shell script with jstest, how can I get a gamepad to interact with the script

shell-script

I have been partially successful with this, but I am stuck. Here is my script:

I want to prompt the user, wait for input from a USB gamepad, and then execute a command based on which button is pressed.

if lsusb | grep -q '0583:2060'
then
  echo "press the A button"
  #
  if jstest --event /dev/input/js0 | grep -q "number 0, value 1"
  then
    echo "you pressed the A button"
  else
    echo "you pressed the NOT A button"
  fi
fi

It checks for the gamepad being connected just fine. It also checks the jstest and echos "you pressed the A button" when I press the A button.

I can't get it to execute the "else" part in this situation though, as grep filters only "button 0, value 1" from jstest (the A button), which means if I am not pressing the A button jstest is piping NOTHING to grep, it always waits for the A button.

I was thinking maybe there was some way to do:

grep -q "number ., value 1"

which will return ANY button being pressed, and then have different commands executed based on what what grep shows. I thought I could use a case statement for this, but I can't get jstest to work with case.

I feel like jstest isn't meant for this kind of stuff, only to test, but extensive googling has shown me no other options for interacting with a game pad through a script.

How can I make a shell script that prompts the user, waits for a button press, then executes different commands based on which button was pressed?

Best Answer

You need to get grep to output the matching text, and stop after a match. You also need to filter events a bit more thoroughly, since you’re only interested in events of type 1 (buttons):

jstest --event /dev/input/js0 | grep -m 1 "type 1, time .*, number .*, value 1"

This will keep jstest running until you press a button, then output the event information. You can process this using read to find the number of the button that was pressed:

jstest --event /dev/input/js0 | grep -m 1 "type 1, time .*, number .*, value 1" | read _ _ _ _ _ _ number _ _
if [ "${number%%,*}" -eq 0 ]
then
    echo "You pressed the A button."
else
    echo "You pressed a button other than A."
fi
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