导入cv2时无法使用PHP exec运行python脚本

I am trying to run a python script which imports cv2 using the PHP exec command. Here is the code:

<?php
 $r =  exec('python /home/me/helloWorld.py');
 echo "Output: $r"
 ?>

I have two python scripts, helloWorld.py and helloOpencv.py

helloWorld.py

print "Hello World"

helloOpencv.py

import cv2
print cv2.__version__

helloWorld.py gives the expected output but helloOpencv.py returns "blank"

Somethings I already tried:

• Changed all permission to '777' to check.
• Checked 'which python', 'whoami'
• cv2.so file in current directory
• Changed max exec time (though it doesnt matter for the helloOpencv.py)

I changed the PHP script to report the return_val as follows:

<?php
 $r =  exec('python /home/me/helloWorld.py', $ouput, $ret_val);
 echo "ret_val: $ret_val"
 ?>

This returned '1' even though there should not be any error in running the helloOpencv.py python script

Please help me find a solution for this problem.