c:\@Work\Perl\monks>perl -wMstrict -le
"my $xxx = 'YYY';
 ;;
 my $boxtxt = 'aaa</boxed-text>bbb';
 print qq{'$boxtxt'};
 ;;
 $boxtxt =~ s{ </boxed-text> }
             {</new-stuff xxx${xxx}xxx>}xmsg;
 print qq{'$boxtxt'};
"
'aaa</boxed-text>bbb'
'aaa</new-stuff xxxYYYxxx>bbb'