How can I use Process class in Arduino Yun to read some stream-data?

Question

Running shell command through Bridge in Arduino Yun through a Process let's say, proc, it gives result and we can read the result bytes using following piece of code.

#include <Bridge.h>
#include <Process.h>

void setup() {
  Bridge.begin();
  Serial.begin(9600);
  while (!Serial);
}

void loop() {
    Process proc;
    proc.runShellCommand("ls /root/");
    while (proc.available() > 0)
        Serial.print((char)proc.read());
    Serial.println();
}

What if I have to access data from a blocking shell command as it gets updated like and event? Such as, some consumer that listens to Kafka or Mosquitto subscribed topic. Whenever that topic is updated/published with new data, the listener gets it.

How can I model such structure using Arduino Yun program using Bridge.

Answer 1

You can do it quite easily. Run that particular command with nohup, in that case, file with the name nohup.out would be created. then after that run a script that continuously monitors that nohup.out file in case of any change in the size of nohup.out, get the latest data and push that data to anywhere you want.