[PHP] Program execution

[Czapáry Gábor]

Hi!

This happens only when I use php as a module:
When I'd like to run a command with exec or system function I got always this message
and the program never executes:
Warning: Unable to fork [the command's name what I'd like to run] in filename on line 
XY

What' the matter?

                                            Thanks: czg