Executing Python Script with PHP Variables

Question

I am writing a simple application that uses information from a form, passes it through $_POST to a PHP script that executes a python script and outputs the results. The problem I am having is that my python script is not actually running with the arguments being passed in.

process3.php file:

<?php
     $start_word = $_POST['start'];
     $end_word = $_POST['end'];
     echo "Start word: ". $start_word . "<br />";
     echo "End word: ". $end_word . "<br />";
     echo "Results from wordgame.py...";
     echo "</br>";
     $output = passthru('python wordgame2.py $start_word $end_word');
     echo $output;
?>

Output:

Start word: dog
End word: cat
Results from wordgame.py...
Number of arguments: 1 arguments. Argument List: ['wordgame2.py']

At the top of my wordgame2.py, I have the following (for debugging purposes):

#!/usr/bin/env python
import sys
print 'Number of arguments:', len(sys.argv), 'arguments.'
print 'Argument List:', str(sys.argv)

Why isn't the number of arguments being passed = 3? (Yes, my form does send the data correctly.)

Any help is greatly appreciated!

Edit: I might add that it does run when I explicitly tell it the start and end word... something like this:

$output = passthru('python wordgame2.py cat dog');
echo $output

What do you see when you `echo 'python wordgame2.py $start_word $end_word'` in your php file? — GWW, Nov 05 '13 at 04:09
After adding that line, it now outputs: Start word: dog End word: cat Results from wordgame.py... python wordgame2.py dog cat Number of arguments: 1 arguments. Argument List: ['wordgame2.py'] — Micah, Nov 05 '13 at 04:14
I think the mistake lies in `$output = passthru('python wordgame2.py $start_word $end_word');` Try this `$output = passthru('python wordgame2.py '.$start_word." ".$end_word);` Maybe, python is rejecting the arguments due to $ keyword (or maybe $ is invoking the shell for variable repplacement) — shad0w_wa1k3r, Nov 05 '13 at 04:22

score 18 · Accepted Answer · edited May 23 '17 at 12:09

18

Update -

Now that I am aware of PHP, the mistake lies in using the single-quotes '. In PHP, single quoted strings are considered literals, PHP does not evaluate the content inside it. However, double quoted " strings are evaluated and would work as you are expecting them to. This is beautifully summarized in this SO answer. In our case,

$output = passthru("python wordgame2.py $start_word $end_word");

would work, but the following won't -

$output = passthru('python wordgame2.py $start_word $end_word');

Original answer -

I think the mistake lies in

$output = passthru("python wordgame2.py $start_word $end_word");

Try this

$output = passthru("python wordgame2.py ".$start_word." ".$end_word);

edited May 23 '17 at 12:09

Community

1
1

answered Nov 05 '13 at 04:25

shad0w_wa1k3r

12,955
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1

Wouldn't the obvious solution be using " instead of '? No need to concatenate when " does variable interpolation. – scandinavian_ Nov 05 '13 at 08:05
Hmm...am not much familiar with php (none at all), so only my answer begins with *I think...* – shad0w_wa1k3r Nov 05 '13 at 08:07
1

Also, probably good to use `escapeshellarg()` on the two arguments passed in when concatenating. – Terry Feb 19 '16 at 23:33

score 4 · Answer 2 · answered Nov 05 '13 at 04:25

4

Thank you for your contributions. I have figured out my problem with this simple fix:

$command = 'python wordgame2.py ' . $start_word . ' ' . $end_word;
$output = passthru($command);

In order for passthru to properly handle the php variables, it needs to be concatenated into the string before executing.

answered Nov 05 '13 at 04:25

Micah

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Instead of posting your answer, which is ashish's answer, please accept his answer. – aIKid Nov 05 '13 at 04:30
I had posted this before I saw his answer. Please look at the time stamp. – Micah Nov 05 '13 at 05:36
1

Actually, I answered 7 seconds before :) The downvote was unnecessary/unverified. – shad0w_wa1k3r Nov 05 '13 at 08:09

score 0 · Answer 3 · answered Dec 26 '20 at 20:57

0

well if I understood you want pass a big amount of text like content of something, so the right way is;

$output = passthru("python wordgame2.py ".json_encode($end_word)." ".json_encode($start_word));

answered Dec 26 '20 at 20:57

demopix

159
6

Executing Python Script with PHP Variables

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