use IO::File;

my $files = {
  'x', 'a',
  'y', 'b',
  'z', 'c'
};

for( keys %{$files} ){

  $read  = new IO::File "< $_";
  die "can't open_r $read: $!" unless defined($read);
  $write = new IO::File "> $files->{$_}";
  die "can't open_w $write: $!" unless defined($write);

  print $write $_ while <$read>;
  
  $read->close;
  $write->close;
}