Running a Python script from PHP

I'm trying to run a Python script from PHP using the following command:

exec('/usr/bin/python2.7 /srv/http/assets/py/switch.py arg1 arg2');

However, PHP simply doesn't produce any output. Error reporting is set to E_ALL and display_errors is on.

Here's what I've tried:

• I used python2, /usr/bin/python2 and python2.7 instead of /usr/bin/python2.7
• I also used a relative path instead of an absolute path which didn't change anything either.
• I tried using the commands exec, shell_exec, system.

However, if I run

if (exec('echo TEST') == 'TEST')
{
    echo 'exec works!';
}

it works perfectly fine while shutdown now doesn't do anything.

PHP has the permissions to access and execute the file.

EDIT: Thanks to Alejandro, I was able to fix the problem. If you have the same problem, don't forget that your webserver probably/hopefully doesn't run as root. Try logging in as your webserver's user or a user with similar permissions and try to run the commands yourself.

Tested on Ubuntu Server 10.04. I hope it helps you also on Arch Linux.

In PHP use shell_exec function:

> Execute command via shell and return the complete output as a string. > > It returns the output from the executed command or NULL if an error > occurred or the command produces no output.

<?php 

$command = escapeshellcmd('/usr/custom/test.py');
$output = shell_exec($command);
echo $output;

?>

Into Python file test.py, verify this text in first line: (see shebang explain):

#!/usr/bin/env python

> If you have several versions of Python installed, /usr/bin/env will > ensure the interpreter used is the first one on your environment's > $PATH. The alternative would be to hardcode something like > #!/usr/bin/python; that's ok, but less flexible. > > In Unix, an executable file that's meant to be interpreted can indicate > what interpreter to use by having a #! at the start of the first line, > followed by the interpreter (and any flags it may need). > > If you're talking about other platforms, of course, this rule does not > apply (but that "shebang line" does no harm, and will help if you ever > copy that script to a platform with a Unix base, such as Linux, > Mac, etc).

> This applies when you run it in Unix by making it executable > (chmod +x myscript.py) and then running it directly: ./myscript.py, > rather than just python myscript.py

To make executable a file on unix-type platforms:

chmod +x myscript.py

Also Python file must have correct privileges (execution for user www-data / apache if PHP script runs in browser or curl) and/or must be "executable". Also all commands into .py file must have correct privileges.

Taken from php manual:

> Just a quick reminder for those trying to use shell_exec on a > unix-type platform and can't seem to get it to work. PHP executes as > the web user on the system (generally www for Apache), so you need to > make sure that the web user has rights to whatever files or > directories that you are trying to use in the shell_exec command. > Other wise, it won't appear to be doing anything.

I recommend using passthru and handling the output buffer directly:

ob_start();
passthru('/usr/bin/python2.7 /srv/http/assets/py/switch.py arg1 arg2');
$output = ob_get_clean(); 

If you want to know the return status of the command and get the entire stdout output you can actually use exec:

$command = 'ls';
exec($command, $out, $status);

$out is an array of all lines. $status is the return status. Very useful for debugging.

If you also want to see the stderr output you can either play with proc_open or simply add 2>&1 to your $command. The latter is often sufficient to get things working and way faster to "implement".

To clarify which command to use based on the situation

exec() - Execute an external program

system() - Execute an external program and display the output

passthru() - Execute an external program and display raw output

Source: http://php.net/manual/en/function.exec.php

Alejandro nailed it, adding clarification to the exception (Ubuntu or Debian) - I don't have the rep to add to the answer itself:

sudoers file: sudo visudo

exception added: www-data ALL=(ALL) NOPASSWD: ALL

In my case I needed to create a new folder in the www directory called scripts. Within scripts I added a new file called test.py.

I then used sudo chown www-data:root scripts and sudo chown www-data:root test.py.

Then I went to the new scripts directory and used sudo chmod +x test.py.

My test.py file it looks like this. Note the different Python version:

#!/usr/bin/env python3.5
print("Hello World!")

From php I now do this:

$message = exec("/var/www/scripts/test.py 2>&1");
print_r($message);

And you should see: Hello World!

The above methods seem to be complex. Use my method as a reference.

I have these two files:

• run.php

• mkdir.py

Here, I've created an HTML page which contains a GO button. Whenever you press this button a new folder will be created in directory whose path you have mentioned.

run.php

<html>
 <body>
  <head>
   <title>
     run
   </title>
  </head>

   <form method="post">

    <input type="submit" value="GO" name="GO">
   </form>
 </body>
</html>

<?php
	if(isset($_POST['GO']))
	{
		shell_exec("python /var/www/html/lab/mkdir.py");
		echo"success";
	}
?>

mkdir.py

#!/usr/bin/env python    
import os    
os.makedirs("thisfolder");

This is so trivial, but just wanted to help anyone who already followed along Alejandro's suggestion but encountered this error:

> sh: blabla.py: command not found

If anyone encountered that error, then a little change needs to be made to the php file by Alejandro:

$command = escapeshellcmd('python blabla.py');

Inspired by Alejandro Quiroz:

<?php 

$command = escapeshellcmd('python test.py');
$output = shell_exec($command);
echo $output;

?>

Need to add Python, and don't need the path.

All the options above create new system process. Which is a performance nightmare. For this purpose I stitched together PHP module with "transparent" calls to Python.

https://github.com/kirmorozov/runpy

It may be tricky to compile, but will save system processes and will let you keep Python runtime between PHP calls.