The inbuilt sort function is quite powerful, but syntax can be sometimes too complicated for simple things like sorting a tab delimited file. Fortunately, there is a cpan module Sort::Fields, that has a method with an extremely straightforward syntax. The basic function in the module is fieldsort, that can take three arguments, first, the delimiter ( in your case tab ), then which columns you want to sort on ( it can take multiple columns, and you can specify reverse, numerical sorts ) and finally the array containing the data. There is no need to worry about anything else. I deal with tab-delimited data frequently, and this module saves my skin all the time. Finally after all the blabber... here's how your data can be sorted ...

use strict;
use Sort::Fields;
use Data::Dumper;

open (INP,"data.txt") || die "cant open data.txt !";
my @data = <INP>;
chomp (@data);

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

my @sorted = fieldsort '\t', [10], @data;

print "\nafter sorting\n";
print Dumper @sorted;
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Note that fieldsort counts columns starting from 1 and not from 0.

hope this helps!

perliff