1, linux rw in maintenance mode
After enter into the maintenance mode, sometimes you need to modify the system files, but you don't have the rw access right to the system file, can use this command to reload the file system as the rw mode.
mount -o remount, rw /
2, create the extended partition
maximum the linux system can create only 4 primary partition, and sometimes you need to create more than four partitions, then you need to create the extended partitions, the command sequence as,
fdisk /dev/sda n-l(create the extended partition)-size-t-label-w