enable generating barcodes in script

                echo "    ...using this as $barcodefile"

            else

                echo "generating $barcodefile of barcode length $minlength"

                # generating permutations of ATCG of barcode length (non-standard evaluation required to run in script)

                echo $(eval echo $(for ii in $(eval echo {1..${minlength}}); do echo "{A,T,C,G}"; done |  tr "\n" " " | sed "s/ //g" | xargs -I {} echo {})) | sed 's/ /\n/g' | sort | uniq > ${barcodefile}

            fi

        fi