use warnings;
use strict;

my $str = 'a|b|c d    e  ';
$str =~ s/[\s|]/_/g;
print "$str\n";

$str = "w\nx\ny\nz";
$str =~ s/\n/ /g;
print "$str\n";

__END__

a_b_c_d____e__
w x y z