PHP exec() will not execute shell command when executed via browser

execphpsystem

I have a certain PHP script that calls exec() to execute a command to convert a PDF to JPG. This command works fine in bash.

To preempt your initial troubleshooting guesses, note the following:

  • safe_mode = Off
  • Permission on the directory containing the PDF and the script is set to 777, and this directory is also where the JPG is being written.
  • The command I am passing to exec() explicitly points to the binary being used (e.g. /usr/local/bin/convert).
  • display_errors = On
  • error_reporting = E_ALL
  • disable_functions = [blank]
  • I am echoing exec()'s output and it returns nothing. The command being run by default returns nothing.

When I call this PHP script from the browser (visiting http://www.example.com/script.php), exec() does not execute its argument.

IMPORTANT: I know that there are no issues with my script or the way I have constructed the bash command, because from bash, I can execute the script with 'php' and it works (e.g. 'php script.php' converts the file)

I have also tried switching out exec() with system().

Last, I have had this issue once before in the past but cannot remember how I fixed it.

I know there is something I am missing, so I hope someone else has experienced this as I have and remembers how to fix it!

Thank you in advance for any assistance you can provide.

Alex

Best Solution

Add 2>&1 to the end of your command to redirect errors from stderr to stdout. This should make it clear what's going wrong.

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