I had a problem while using PHP `exec()`. I am not able to figure out the issue and I have tried with following code:

```
exec("pdfcrop --margins '-6 -2 -3 -2' '/home/username/pdf/Figure 1 Timeline of Virtual Sim Use/page.01.pdf' '/home/username/pdf/out/output.pdf'", $output, $error);

```

Whenever I use this commands in `exec()` it returns status code of 2 but if I use this command to my terminal then it works well. So kindly give your suggestion to solve this problem.

thank you..