1. 仅是参考，比较危险，出问题自负

root@CentOS-7:~# fdisk -l  /dev/mmcblk0

Disk /dev/mmcblk0: 31.3 GB, 31268536320 bytes, 61071360 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
Disk label type: dos
Disk identifier: 0x240d1f0f

        Device Boot      Start         End      Blocks   Id  System
/dev/mmcblk0p1           32831    5119999          ...   83  Linux

看到/dev/mmcblk0p1 起始扇区 32831

cat > fdisk.cmd <<-EOF
d

n
p
1
32831
w
EOF
echo "fdisk.cmd done!"
echo "disk partition..."
fdisk /dev/mmcblk1 < fdisk.cmd
mount -o remount,rw /
resize2fs /dev/mmcblk0p1 
df -h

2. 安全一点的办法

centos

#yum update
yum install cloud-utils-growpart -y 

debian

# apt-get  update
apt-get install cloud-guest-utils xfsprogs -y 

扩展mmcblk0设备的第1分区

growpart /dev/mmcblk0 1 
resize2fs /dev/mmcblk0p1