SD Card Reading and Writing with Linux dd


Just a quick post as a personal note for a reminder on how to use the dd command to read and write SD card images. This can be useful when working locally with Raspberry Pi and NVidia Jetson style embedded computers.

Determine the Device Location

We need to determine the path for the SD card we intend to use, whether the operation is reading or writing.

sudo fdisk -l

Returns a list of all of the available partitions and drives. We are interested in this 64GB SD card.

Disk /dev/mmcblk0: 59.64 GiB, 64021856256 bytes, 125042688 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: 0x87c6153d

Device         Boot  Start       End   Sectors  Size Id Type
/dev/mmcblk0p1 *      2048    526335    524288  256M  c W95 FAT32 (LBA)
/dev/mmcblk0p2      526336 125042654 124516319 59.4G 83 Linux

Now we need to unmout the media before we can safely read or write from it with dd.

sudo umount /dev/mmcblk0


The command below will create a sd_card_image.img image file from the SD card image in your users home directory.

sudo dd if=/dev/mmcblk0 of=~/sd_card_image.img bs=4M status=progress


This command will take a sd_card_image.img image file from your local home directory and write it to your SD card.

sudo dd of=/dev/mmcblk0 if=~/sd_card_image.img bs=4M status=progress

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