Name "main::FILE1" used only once: possible typo at sort2.pl line 9.                                                                                           
Name "main::FILE2" used only once: possible typo at sort2.pl line 7.                                                                                          
readline() on unopened filehandle FILE2 at sort2.pl line 7.                                                                                                    
readline() on unopened filehandle FILE1 at sort2.pl line 9.