Is it possible to write to the stdin of an Arduino Yun Linux process launched by the Bridge Process of a sketch?
Context: I have a control and logging application that needs to log data to a Google Drive spreadsheet using Temboo.com. While I have successfully implemented this functionality in the Arduino sketch following Temboo examples, the sketch size exceeds the available AVR memory. To address this issue, I intend to split the functionality: control and data acquisition on the AVR side and Python-Temboo on the Linux side.
To start testing this approach, I created a simple Python script stdinFile.py:
import sys
# Read the string from stdin
rowData = sys.stdin.readline()
f = open("blah.txt","w")
f.write(rowData)
f.close
sys.exit(0)
I executed this script via an ssh session and input a series of characters, which successfully resulted in writing to a file:
root@Arduino:~# python /root/stdinFile.py
adsfsadfdsaf
root@Arduino:~# cat blah.txt
adsfsadfdsaf
However, I am facing challenges while trying to achieve the same behavior from within the Arduino sketch. The blocking nature of the Process.run() method is preventing successful execution as the process blocks the sketch before allowing writes:
Process p; // Create a process and name it "p"
p.begin("python"); // Launch the "Python" command as a process
p.addParameter("/root/stdinFile.py"); // Include the script name for the "python" process
p.run(); // This is blocking! Script hangs here waiting for stdin
char record[]="2015-09-06,21:20:00,F,T,F,F,18.3,18.4,19.3,19.4,30.6,28.6";
for( char * src = record; *src != '\0'; src++) {
p.write(*src);
}
p.flush();
I also attempted to perform the writes prior to p.run(), essentially filling the stdin stream before script execution, but this approach did not yield any desired outcomes either.
Any suggestions or help would be greatly appreciated!