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.