Cloning a microSD Card using UNIX `dd` Command¶

This guide explains how to clone a microSD card using the dd command on UNIX and UNIX-like systems.

Table of Contents¶

Cloning a microSD Card using UNIX dd Command
Table of Contents
Identify the microSD Card Device
Unmount the microSD Card
Create a Backup Image
Copy the Backup Image to New microSD Cards
Expand the Filesystem (Optional)

Identify the microSD Card Device¶

First, identify the device name for your microSD card. Use either lsblk or df to list devices and their mount points.
```
lsblk
```
Or:
```
df -h
```
Look for the device corresponding to your microSD card. It's generally something like /dev/sdX or /dev/mmcblkX, where X is a letter.

⚠️ Caution: Be very careful to identify the correct device, as choosing the wrong one could result in data loss.

Unmount the microSD Card¶

Before copying data, unmount the partitions of the microSD card to ensure that no data is being read or written during the cloning process.
```
sudo umount /dev/sdX*
```

Create a Backup Image¶

Use the dd command to create an image file of the microSD card.
```
sudo dd if=/dev/sdX of=raspberrypi_backup.img bs=4M status=progress
```
- if: Input File — the device you are copying from (your microSD card).
- of: Output File — the image file you are creating.
- bs: Block Size — specifies how much data should be read at each iteration. 4M is usually a good size.
- status=progress: shows the progress during the copy.

Copy the Backup Image to New microSD Cards¶

To clone the image onto a new microSD card, insert the new card and identify it just like you did in the first step.
```
sudo dd if=raspberrypi_backup.img of=/dev/sdY bs=4M status=progress
```
Replace /dev/sdY with the device name of your new microSD card.

⚠️ Caution: Again, be very careful to identify the correct device to avoid data loss.

Expand the Filesystem (Optional)¶

If your new microSD card is larger than the original, you might need to expand the filesystem to use the additional space. You can do this using raspi-config on the Raspberry Pi.
```
sudo raspi-config
```
Navigate to Advanced Options > Expand Filesystem.

After following these steps, you should have successfully cloned your Raspberry Pi's microSD card.

Note: The dd command can be very dangerous if misused. Always double-check your device names and ensure you understand the commands you're running.

Cloning a microSD Card using UNIX dd Command¶