yes, that's possible, but why don't you show the code you tested?

I modified my example and the result looks like the wanted...

while ( my $line = <DATA> ) {
    chomp $line;

    # remove the spaces from start of line
    if ( ! ( $line =~ s/^\s+// ) ) {
        print "\n" if $. != 1;
    }

    # remove spaces from end of line
    $line =~ s/\s+$//;
    print $line;
}

__DATA__
firstline54324563213612531436436463246324634
         secondlidfndsfdsfdsfd
         thirdlinedsfsdf   
firstline54324563213612531436436463246324634
         secondlidfndsfdsfdsfd
         thirdlinedsfsdf
[download]

Result:

$ perl guess.pl
firstline54324563213612531436436463246324634secondlidfndsfdsfdsfdthird
+linedsfsdf
firstline54324563213612531436436463246324634secondlidfndsfdsfdsfdthird
+linedsfsdf
[download]