drive_type<vector(mode="expression",length=length(my_file$xx))
for(i in 1:length(my_file$xx)){
    serial_num<-my_file$xx[i]
temp_1<-my_file[grep("serial_num",rownames(my_file)), ]
if('6' %in% temp_1$yy){
  drive_type[i]<-'12header'}
else {
  drive_type[i]<-'6header'}
}