<.... line 200 ....> <.... line 201 ....> <.... line 202 ....> ##

##

    grep -A 3 -B 3 xxx  file-B >> file-A

##

##

    $out = qx/grep ... /     #note that $out contains new lines

##

##

    $last = qx/tail -1 $fileA/

##

##

      if (($last =~ /\S/) && ($out =~/$last(.*)/)) {
         $out = $1
      }