#! perl -slw
use strict;

my %ops;
for my $op ( qw[ < <= == >= > != lt le eq ge gt ne ] ) {
    $ops{ $op } = eval "sub{ \$_[0] $op \$_[1] }";
}

printf "Enter criteria: ";
my( $f, $op, $c ) = split ' ', <STDIN>;

local $\;
while( <> ) {
    my @f = split ',';
    print if $ops{ $op }->( $f[ $f ], $c );
}