shell whoami doesn't equal php shell_exec whoami?

Question

In a shell I do simple whoami and I get geoff, which is good, since that\'s who I am.

In a php file I have shell_exec(\'whoami\'); and I get nobody.

This see

Answer 1

@anubhava is correct about why you get two different answers when you run whoami. However, if you're trying to convert a PDF to a PNG using ImageMagick (like in your comment on the question), even using the full path to ImageMagick's convert won't work if the script's PATH doesn't contain the path location to Ghostscript also. Without messing with any user paths, you could add:

putenv("PATH=/usr/local/bin:/usr/bin:/bin");

Or something similar depending on your setup. The gs executable has to be in your script user's path somewhere or ImageMagick will fail to convert PDF or EPS files.