c:\@Work\Perl>perl -wMstrict -MData::Dump -le
"my @lines = ('', ' ', '  ', 'x', ' x', 'x ', ' x ', '  x  ',);
 ;;
 my @no_empties = grep { $_ !~ /^(?:\s+|)$/ } @lines;
 ;;
 dd \@no_empties;
"
["x", " x", "x ", " x ", "  x  "]

##</code><code>##

c:\@Work\Perl>perl -wMstrict -MData::Dump -le
"my @lines = ('', ' ', '  ', 'x', ' x', 'x ', ' x ', '  x  ',);
 ;;
 my @no_empties = grep m{\S}xms, @lines;
 ;;
 dd \@no_empties;
"
["x", " x", "x ", " x ", "  x  "]