printf("you always need to specify two argument, source and target,\n");
printf("matching the system call ones, if one of them is not needed\n");
printf("just pass an empty string\n");
+ printf("you also need to specify options and flag, give an empty \n");
+ printf("string for option if you don't want to set any, i.e. \n");
+ printf(" ./mymount -t ext4 -o "" -f remount,rdonly /dev/sdb1 /mnt");
exit(1);
}