php passthru returns no output

Question

I am trying to call a python script from php. However, I cannot figure out how to return the result to my php script in order to use it there. My php script is as follows:

<?php
  $input = 'help';
  $output = passthru("/usr/bin/python3.5 /path/test.py '$input'");
  echo $output;
?>

whilst my python script 'test.py' is:

import sys
json2 = sys.argv[1]

Answer 1

That's because your python script returns nothing. Just doing:

json2 = sys.argv[1]

Only assigns the value to json2. I suspect you're trying to do something like:

import sys
json2 = sys.argv[1]
print json2

That seems to work just fine:

~ # php -a             
Interactive shell

php > $input = 'help';
php > $output = passthru("/usr/bin/python test.py '$input'");
help

Update:

Based on your comment. You're looking for exec() instead:

~ # php -a     
Interactive shell

php > $input = 'help';
php > $output = exec("/usr/bin/python test.py '$input'");
php > echo $output;
help

Note that your Python script has to output something. Just assigning a variable is not going to work, since PHP cannot interpret your Python code for you. It can only run the script and do something with the script's output.