# An evil collection of one-liners to make this five-line
# script which sorts a file by a date field.  It's designed
# for massive files, and indexes directly into the file.

open(FD,"data") || die;

my ($loc,@a) = (tell(FD));

push(@a,[$loc,(split /\|/)[4]]),$loc = tell(FD) while(<FD>); # 4 is the datefield

seek(FD,$_,0), $_ = <FD>,
  print for map { $_->[0] }
            sort { $a->[1] cmp $b->[1] }
            map { [$_->[0],
                  sprintf "%04d%02d%02d",(split /\//,$_->[1])[2,0,1]] } @a;

close FD;