my $index = pack 'N', 0; $index .= pack 'N', tell FILE while ; for( my $line_idx = $s; $line_idx < $fileLastLine; $line_idx++ ) { my $line = unpack( 'N', substr($index, $line_idx*4, 4)); seek FILE, $line, 0; chomp( $_ = ); my $line_str = $_;