An alternative solution to the above would be something like this

my @files = ('file1','file2','file3','file4');
# use a glob if you prefer

my %hash;
foreach my $file_name (@files){
        open my $fh, '<',$file_name || die "$!";
        while (<$fh>){
                chomp;
                next if (/^\s*$/);
                my ($id,$val) = split /\t/;
                $hash{$id}{$file_name} = $val;
        }
        close $fh;
}

foreach my $id (sort keys %hash){
        print "$id\t";
        print $hash{$id}{$_} ?  "$hash{$id}{$_}\t" : "0\t" foreach (@f
+iles);
        print "\n";
}
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