use constant CHUNK => 4*1024;
sub pseek {
   my( $p, $o ) = @_;
   read( $p, my $discard, $CHUNK ), $o -= $CHUNK while $o > $CHUNK;
   read( $p, $discard, $o-1 );
   return $o;
}

##</code><code>##

open(FILE, $path) || die "$!\n";
seek(FILE, $offset, 0);
while(<FILE>) {
    # do stuff
}
close FILE;

##</code><code>##

open(FILE, '-|', "$cat $file") || die "$!\n";