#!/usr/bin/perl -w
my $db = '/some/file';
my $letter = 'Y';
open DB, $db or die "Can't read $db: $!\n";
my @matches;
while(<DB>){
    push @matches, $_ if m/^$letter/i;
}
close DB;
print sort @matches;

##</code><code>##

$ grep -i -e ^Y db.file | sort