Fair enough. I should have read the question!

I have modified the technique to build an AoA in memory before writing it out. The OP wasn't clear on how files of differing length were to be treated. The code below expands the AoA as necessary to cope with files of different lengths.

my @lines;
my $line = 0;
my $filecount = 0;

while (<>) {
    chomp (${$lines[$line++]}[$filecount] = $_);
    if (eof) {
        $line = 0;
        $filecount++;
    }
}
foreach (@lines) {
    $#{$_} = $filecount -1;
    print join("\t", @{$_}), "\n" ;
}
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