in reply to Remove SOME new lines

Add /s to your substitution:

$s = "fred\nundone\nfred\nunknown\nfred\nuncaring\n";;
$t = $s; $s =~ s[\nu][u]g; print $t;;
fred
undone
fred
unknown
fred
uncaring

$t = $s; $s =~ s[\nu][u]sg; print $t;;
fredundone
fredunknown
freduncaring

[download]
With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority". I knew I was on the right track :)
In the absence of evidence, opinion is indistinguishable from prejudice. Not understood.

In Section Seekers of Perl Wisdom