Scalar Value @first better written as $second
use of uninitalized value within @first in print

use strict;
use warnings;
use List::Util 'shuffle';
use Tie::File;

my @first;
my @second;
my @third;
my @fourth;

tie @first, 'Tie::File', "first.txt" or die "Can not open file 1!";
@first=shuffle(@first);

tie @second, 'Tie::File', "second.txt" or die "Can not open file 2!";
@second=shuffle(@second);

tie @third, 'Tie::File', "third.txt" or die "Can not open file 3!";
@third=shuffle(@third);

tie @fourth, 'Tie::File', "first.txt" or die "Can not open file 4!";
@fourth=shuffle(@fourth);

print @first[0];
print " ";
print @second[0];
print " ";
print @third[0];
print " ";
print @fourth[0];