python - Php exec() command with & - php script still hanging -

i have constellation 3 involved scripts, written in php, shell , python. running on raspberry pi b+ latest raspbian.

the python script switches wireless socket lib: http://github.com/xkonni/raspberry-remote.git , following:

#!/usr/bin/env python import time import subprocess import rpi.gpio gpio import sys  channelcode = sys.argv[1] unitcode = sys.argv[2] duration = sys.argv[3]  # use pins on board. gpio.setmode(gpio.board) # pin 18 gpio.setup(12, gpio.in)  while 1:     if gpio.input(12) == gpio.low:         subprocess.call('sudo send ' + channelcode + ' ' + unitcode + ' 1', shell=true)         time.sleep(float(duration))         subprocess.call('sudo send ' + channelcode + ' ' + unitcode + ' 0', shell=true)         # 1 sec sleep 1 low, instead of multiple because of high sensitivity.         time.sleep(1)         # don't slow down system because of endless loop.         time.sleep(0.01) 

the endless loop recognizing light-barrier interrupt , shall run still user interrupts via webinterface.

because of needed sudo privileges lib, created bash script, executed sudo www-data (only script - security).

the shell script starts python script endless loop or kills it:

#!/bin/bash  # if true, python script shall activated, if false should killed.  if [ $1 = "true" ]              python /var/www/html/cat-feeder/app/resources/pi/light-barrier.py $2 $3 $4 & fi if [ $1 = "false" ]             kill -9 `ps -ef | grep light-barrier.py | grep -v grep | awk '{print $2}'` fi  exit 0 

in php shell script executed arguments killing python script , end loop or start script:

if ($lightbarrieractive === true) {     exec('sudo /var/www/html/cat-feeder/app/resources/pi/catfeeder-sudo-script.sh false &'); }  else {     exec('sudo /var/www/html/cat-feeder/app/resources/pi/catfeeder-sudo-script.sh true 11010 4 1 &'); } 

now problem: php exec command kill work fine. exec command arguments shell script activating python script causes hanging of php script.

the weird thing: executing shell script command line exact same command working!

i tried executing nohup command, same thing.

i tried this: php hanging while exec() bash script think doesn't trigger shell script, because doesn't produce output.