In the command
exec($command, $return_array, $return_value)If you execute above command via PHP and get $return_array as empty and $return_value as 5, then that means something is wrong. If the command successfully executes, it should return a value of 0.
5 means Access denied. Similarly, Here are list of some common return codes and what they means 0 The operation completed successfully. 1 Incorrect function. 2 The system cannot find the file specified. 3 The system cannot find the path specified. 4 The system cannot open the file. 5 Access is denied. 6 The handle is invalid. 7 The storage control blocks were destroyed. 8 Not enough storage is available to process this command. 9 The storage control block address is invalid. 10 The environment is incorrect. . . .
The complete list can be found @ Hikesoftware