PHP Passthru Mastery Return Codes Decoded for Success

The following code ran fine in PHP under apache but is failing to run under nginx/php-fpm: exec( "/usr/bin/xvfb-run -a -s '-screen 0 640x480x16' The [, array output [ is returned from the executable file. The file is a verisign file for Payflow Pro, the array output is telling me it ... I need help with the following problem: I'm running a youtube-dl command over exec() saving the ret code, the output and the return of exec ... I'm trying to exec a .sh script from PHP, however it is not executing. I checked the error logs, and I'm getting the 'sh: Permission denied' error. If you really must use user data as input to your program calls, pass it through the special function escapeshellcmd() first—it takes your input, and returns it ... Remove exec from the disabled_functions and leaving it at PHP 8.0 always makes the error goes away. Just seems odd that exec() is only needed ... doesn't return anything via any exec/passthru call from php. I am trying to execute system command, but am getting a return value of 255. (i guess from bash) Here is my php script: '; passthru('lame ... pdf (1 page). and when i compile from php I get. Error 256 (driver return code) generating output; [174] => file my_file.pdf may not be valid. log and the above three php commands don't trigger an error. Any ideas on what's going on here?