pi@raspbian:~$ sudo fdisk /dev/mmcblk0

Welcome to fdisk (util-linux 2.33.1).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.

Command (m for help): p
Disk /dev/mmcblk0: 59.5 GiB, 63864569856 bytes, 124735488 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x7134b5bb

Device         Boot  Start      End  Sectors  Size Id Type
/dev/mmcblk0p1 *      2048   526335   524288  256M  c W95 FAT32 (LBA)
/dev/mmcblk0p2      526336 16777215 16250880  7.8G 83 Linux

Command (m for help): d
Partition number (1,2, default 2): 2

Partition 2 has been deleted.

Command (m for help): n
Partition type
   p   primary (1 primary, 0 extended, 3 free)
   e   extended (container for logical partitions)
Select (default p): p
Partition number (2-4, default 2):
First sector (526336-124735487, default 526336):
Last sector, +/-sectors or +/-size{K,M,G,T,P} (526336-124735487, default 124735487):

Created a new partition 2 of type 'Linux' and of size 59.2 GiB.
Partition #2 contains a ext4 signature.

Do you want to remove the signature? [Y]es/[N]o: n

Command (m for help): w

The partition table has been altered.
Syncing disks.
pi@raspbian:~$ sudo reboot

pi@raspbian:~$ sudo resize2fs /dev/mmcblk0p2
resize2fs 1.44.5 (15-Dec-2018)
Filesystem at /dev/mmcblk0p2 is mounted on /; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 4
The filesystem on /dev/mmcblk0p2 is now 15526144 (4k) blocks long.

pi@raspbian:~$ df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/root        59G  7.1G   49G  13% /
devtmpfs        1.9G     0  1.9G   0% /dev
tmpfs           1.9G   12K  1.9G   1% /dev/shm
tmpfs           1.9G   17M  1.9G   1% /run
tmpfs           5.0M     0  5.0M   0% /run/lock
tmpfs           1.9G     0  1.9G   0% /sys/fs/cgroup
/dev/mmcblk0p1  256M   69M  188M  27% /boot
tmpfs           386M     0  386M   0% /run/user/1000

 

OK，成功