#!/usr/bin/perl

use strict;

my $var = 'x' x 10000;
my $var_length = length $var;
my $max_length = 100;
my $last_length = 0;

while ($var_length > 100) {
    $last_length+=$max_length;
    $var_length-=$max_length;
    $var =~ s/\S{$last_length}/$&\n/sg;
}

print $var, "\n";