{
  open FILE, $file or die;
  my ($dev,$ino) = stat(FILE);
  flock FILE, 2 or die;
  my ($dev1, $ino1) = stat($file);
  redo unless "$dev $ino" eq "$dev1 $ino1"; 
}
open FILE_OUT, ">$file.tmp" or die;
### ... process FILE into FILE_OUT
close FILE_OUT;
rename "$file.tmp", "$file" or die;
close FILE;