This is my php script
<HTML>
<head>
<h1>Hello</h1>
</head>
<body>
<?php
$command=escapeshellcmd('~/PycharmProjects/Test_1/wiki_update.py 2 2>&1');
$output=shell_exec($command);
echo $output;
?>
</body>
</HTML>
I get no output when I run it through the browser.
When I change the $command=escapeshellcmd('whoami');
it outputs as NOBODY,
I granted permission to nobody for that python script still no output.
I am using xampp for linux and php script in htdocs/xampp.
Are you sure you don't need to change your command to run python?
$command=escapeshellcmd('python ~/PycharmProjects/Test_1/wiki_update.py 2 2>&1');
You also might try specifying absolute path - the ~ alias changes based on current user (which is the web server's user, not yours).