c:\@Work\Perl>perl -wMstrict -le
"my $s = '>nbsp< hi nbsp there';
 print qq{'$s'};
 ;;
 $s =~ s{ nbsp }{\s}xmsg;
 print qq{'$s'};
"
Unrecognized escape \s passed through at -e line 1.
'>nbsp< hi nbsp there'
'>s< hi s there'