Calling a endless Python script from PHP

Question

I have a PHP script that calls a python script. Both running on the same Linux server.

The Python script is running in a "while true" loop. Now when I start the PHP script, it remains in an endless loop and never ends.

If i delete the loop in Python, PHP is running normaly.

PHP:

<html>
 <head>
   <title>PHP</title>
 </head>
 <body>
  <?php 
      shell_exec('sudo python /home/pi/blink.py 1); 
  ?> 
 </body>
</html>

Python:

#!/usr/bin/env python
import RPi.GPIO as GPIO
import time
import sys

GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)
GPIO.cleanup()

GPIO.setup(4, GPIO.OUT)

def blink(self):
    while True:
        time.sleep(0.5);
        GPIO.output(4, GPIO.LOW)
        time.sleep(0.5);
        GPIO.output(4, GPIO.HIGH)

if  str(sys.argv[1]) is '1':
     blink("")
else:
     GPIO.output(4, GPIO.LOW)

Edit: How do I properly start a Python script with an infinite loop using PHP?

@Robert: I guess it is: "How do I properly start a Python script with an infinite loop using PHP?". — Amal
– Amal, Commented Feb 9, 2014 at 15:32
Yes i want to start a Python script with an infinit loop. From PHP — Blindsurfer
– Blindsurfer, Commented Feb 9, 2014 at 15:34

RobertDiep · Accepted Answer · 2014-02-09 15:36:34Z

2

Alright, one option is to include the Linux '&' in your shell_exec() function. This makes the command run in the background, you can't stop it (easily) from within the script though. Code then becomes (note the '&'):

<html>
 <head>
   <title>PHP</title>
 </head>
 <body>
  <?php 
      shell_exec('sudo python /home/pi/blink.py 1 &'); 
  ?> 
 </body>
</html>

This makes the script run in the background forever, or at least until the Pi is rebooted.

answered Feb 9, 2014 at 15:36

RobertDiep

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2 Comments

Blindsurfer Over a year ago

Unfortunately, the parameter '&' does not change anything. The PHP script continues in the endless loop.

RobertDiep Over a year ago

Right, perhaps that's because the output should be redirected to /dev/null. So then it becomens 'shell_exec('sudo python /home/pi/blink.py 1 > /dev/null &')'. Does this work?

Martin Tournoij · Accepted Answer · 2014-02-11 19:47:42Z

2

Thanks to Robert Diepeveen

/dev/null &

This is the missing Piece

<html>
  <head>
    <title>PHP</title>
</head>
<body>
    <?php 
          shell_exec('sudo python /home/pi/blink.py 1 > /dev/null &');
    ?> 
</body>

edited Feb 11, 2014 at 19:47

Martin Tournoij

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answered Feb 11, 2014 at 19:40

Blindsurfer

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Comments

Ferrakkem Bhuiyan · Accepted Answer · 2014-02-09 15:45:18Z

0

exec() — Execute an external program
for more details [php manual][1]

answered Feb 9, 2014 at 15:45

Ferrakkem Bhuiyan

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1 Comment

Blindsurfer Over a year ago

I have tryed the command: exec('sudo python /home/pi/blink.py 1 &', $output, $return_var); but the Result is the same

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