$ perl -le'"%xyz"=~/([\$@*%]|(<))(.*)((?(2)>))/;print"($1)($3)($4)"' (%)(xyz)() $ perl -le'"%xyz>"=~/([\$@*%]|(<))(.*)((?(2)>))/;print"($1)($3)($4)"' (%)(xyz>)() $ perl -le'""=~/([\$@*%]|(<))(.*)((?(2)>))/;print"($1)($3)($4)"' (<)(xyz)(>)