sudo dd if=<RPIimage-sdimg> of=</dev/sdc> bs=4M

Example: sudo dd if=rdk-generic-hybrid-refapp-thunder-image_default_20190829072513.rootfs.rpi-sdimg of=/dev/sdc bs=4M

mkdir -p extblock

fdisk -u -l $1 > extblock/sector.txt

linux_sector=`tail -2 extblock/sector.txt | tr -s ' ' | cut -d'*' -f2 | cut -d' ' -f2 | head -n1`
linux_offset=$((linux_sector*512))

rootfs_sector=`tail -2 extblock/sector.txt | tr -s ' ' | cut -d'*' -f2 | cut -d' ' -f2 | tail -1`
rootfs_offset=$((rootfs_sector*512))

mkdir -p extblock/linux_data
mkdir -p extblock/rootfs_data

mkdir -p extblock/vlinux_backup_data
mkdir -p extblock/vrootfs_backup_data

#sudo mount /dev/mmcblk0p1 extblock/bank0_linux

#--------------------------------------------------------------------------------------------------
# Loop mount + Extract kernel and bootload data of Downloaded image to storage area
#--------------------------------------------------------------------------------------------------

sudo mount -o loop,offset=$linux_offset $1 extblock/linux_data
cp -R extblock/linux_data/* extblock/vlinux_backup_data/
sudo umount extblock/linux_data
rm -rf extblock/linux_data


#--------------------------------------------------------------------------------------------------
# Loop mount + Extract rootfs data of Downloaded image to storage area
#--------------------------------------------------------------------------------------------------

sudo mount -o loop,offset=$rootfs_offset $1 extblock/rootfs_data

cp -R extblock/rootfs_data/* extblock/vrootfs_backup_data
sudo umount extblock/rootfs_data
rm -rf extblock/rootfs_data

For ex. sudo sh extract.sh rdk-generic-hybrid-refapp-thunder-image_default_20190924125426.rootfs.rpi-sdimg

For ex. 
mkdir videomnt
sudo mount /dev/sdb4 videomnt

In above command, storage partition 4 will get mounted to videomnt directory

sudo cp -r extblock/v* videomnt/

sudo cp -r extblock/vrootfs_backup_data/* videomnt/

sudo cp bank_broadband_switch.sh videomnt/lib/rdk/

sudo umount videomnt

#For ex. 
mkdir -p bbmnt
sudo mount /dev/sdb4 bbmnt

#In above command, storage partition 2 will get mounted to bbmnt directory

# Now copy the broad band change scripts from host to broadband image rootfs in partition2 (/dev/sdb2) mounted to bbmnt as below

sudo cp rpi_sw_install1.sh rpi_sw_install.sh swupdate_utility.sh bank_image_switch.sh bank_video_switch.sh imageFlasher.sh bbmnt/lib/rdk/

# Now unmount the bbmnt

sudo umount bbmnt

root@RaspberryPi-Gateway:/lib/rdk# sh bank_video_switch.sh

sh /lib/rdk/bank_broadband_switch.sh