my $foo = '12345678901 23456789012345678901234567890123456789012345678901234567890123456789012345678901234567890';
                                                                                
my $n = 15;
                                                                                
my @chunks = ($foo =~ /(\S{0,$n})\s?/g);
                                                                                
print join "\n",@chunks;