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I'm writing a little script right now which sends some data to the Arduino through a bash shell script. The command that sends the data looks like this:

alias led_green="echo -e -n '\x10' > /dev/ttyACM1"

As you can see, I have /dev/ttyACM1 hard coded into the program. This is problematic, because if I change USB ports the value will change as well, and my script won't work. I'm wonder if there's a way to programatically tell which port the arduino is connected to so the script will always run as long as there's an arduino connected.

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I would suggest switching from alias to a function , which uses a loop to go through a list of the device files.

Assuming there's no other devices , you can use a for loop to determine which device exists.

$ for i in $(seq 0 99) ; do                                                    
>    [ -e "/dev/ttyACM$i"  ] && break                                            
> done

If you echo the value of $i after the loop exits, that will be the value of the found device .

However , if for instance you have /dev/ttyACM0 and /dev/ttyACM1 devices there and they run at different baud rate you can loop through them and test for stty -a -F /dev/ttyACM$i | grep $BAUD_RATE

If both devices run on the same baud rate , well . . . there's not a lot to do - have to use manual way.

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