Text::Wrap seems to do what you want. I think the following regular expression will also do "what you want", as long as there are no words longer than your maximum line lenght:

use strict;
my $line_length = 10;

my $line = '123 1234 12345 123456 1234567';

my @lines = ($line =~ /(.{1,$line_length}(?:\s|$))/g);

print "-" x $line_length,"\n";
print "$_\n" for @lines;
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... but I have only cursory tested that idea. I think it will fail for blanks that fall on the last column. Maybe you can fix that by allowing $line_length to be one larger than what fits onto the line.

Thanks a lot!

Works really good. Now it's my job to spend some spare time and understand the regex!

use strict;

my $str="Reports that say that something hasn't ".
        "happened are always interesting to me " .
        "because as we know, there are known knowns; ".
        "there are things we know we know. We also ".
        "know there are known unknowns; that is to ".
        "say we know there are some things we do not ".
        "know. But there are also unknown unknowns --".
        " the ones we don't know we don't know.";
        
my $picture = '^<<<<<<<<<<<<<<<<<<<< ~~'."\n";

formline ($picture, $str);
print "$^A\n";
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The first node I posted on PerlMonks was Re^2: Tiny little paragraph wrapper in (indirect) reply to Tiny little paragraph wrapper ;).

You mean a substitution. Only the fist half of a substitution is a regular expression.

It's not that hard.

my $l_max = 30;
$str =~ s/(.{0,$l_max}) /$1\n/g;
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Anno