use strict;        # before anything else
use Sort::Fields;  
use Data::Dumper;

open(INP,"data.txt") || die "where's the file eh?";
my @data=<INP>;

chomp (@data); # remove new line characters

print "before sorting...\n";
print Dumper @data;  

#sort the data on the 2nd and the 4th field
#this is numeric sort, as indicated by the "n"

my @sorted = fieldsort '\t', [ '2n', '4n' ], @data;  

print "after sorting...\n";
print Dumper @sorted;