my(@folder_name,$temp1,$temp2); ... @folder_name=; ... push(my @folder_name,); ... $temp1 = pop(@folder_name); $temp2 = pop(@folder_name); #### my(@folder_name,$temp1,$temp2); ... $temp1 = ; ... $temp2 = ; #### mkdir "/var/www/html/piRNA_html/UNAFold/output/$temp2",0777 or die "Cannot make directory /var/www/html/piRNA_html/UNAFold/output/$temp2, error was $!";