Running shell commands with Raspberry Pi

Troubleshooting
1

Hello everyone,
I am trying to run a simple bash command on my RPi located in home directory but nothing really works. I found code example but I guess it works only with Photon.

Process proc = Process::run("script.sh");

Is there any other option?

2

You’ll need to feed the run() command an absolute path; run("/home/pi/script.sh")
Also make sure that the script has permission to execute. From the Raspberry Pi command line, run:
chmod +x /home/pi/script.sh

This should work as long as your script outputs a float like the example from the doc. If you want to output a string, that’s another story. I’m was still trying to work this one out late into the night. It’s been a while since I’ve wrote any C.

I kept getting errors similar to:

conversion from ‘FdStream’ to non-scalar type ‘String’ requested

Great, what’s FdStream? I don’t know, I can’t find a lick of documentation on it or where it came from. My best clue for how to handle it is the line:
float cpuTemp = proc.out().parseFloat();

So we know know we can parse it into a Float, neat. Don’t bother trying parseString(), too easy. But I think we’re on to something.

Now I found in the Arduino docs the following page:
https://www.arduino.cc/en/Serial/ParseFloat

That page is talking about handling serial data. So it seems that we’re dealing with a similar type of data stream and it mentions a lovely little function called readString()
I had to declare a string on it’s own line:
String myIP = proc.out().readString();

And finally

Particle.publish("My IP", String(myIP), PRIVATE);

So my final program looks like this:

// -----------------------------------------
// Execute a script and publish the result
// -----------------------------------------

void setup() {
  // Nothing to set up here
}

void loop() {
  // Run a simple script that outputs the current IPv4 address for this Raspberry Pi.
  Process proc = Process::run("/home/pi/scripts/getIP.sh");
  // Wait for the script to finish
  proc.wait();

  // Convert the FdStream to a string
  String myIP = proc.out().readString();
 
  // Publish the event to the Particle cloud. It will be visible in the Console.
  Particle.publish("My IP", String(myIP), PRIVATE);

  // Repeat after a 30 second pause. Don't need to be running the command constantly.
  delay(30000);
}