How to save image from bootable SD card directly to USB pendrive in Linux Ubuntu
Instead of first saving the SD card image to your home directory, you can write it directly to the USB pendrive.
Here’s exactly how:
🧭 Step-by-Step: Clone boot SD card straight to USB pendrive
1. Identify the devices
Run:
lsblk- Your boot SD card will likely be
/dev/mmcblk0or/dev/sda(since you’re booted from it). - Your USB stick will likely be
/dev/sdbor similar.
For example:
NAME SIZE TYPE MOUNTPOINTmmcblk0 29.7G disk├─mmcblk0p1 256M part /boot└─mmcblk0p2 29.4G part /sdb 31.0G disk└─sdb1 31.0G part /media/usb👉 Here:
- SD card =
/dev/mmcblk0 - USB stick =
/dev/sdb
2. Unmount the USB stick
sudo umount /dev/sdb*(Replace sdb with the correct USB device name.)
This is critical — dd can only write to an unmounted device.
3. Clone the SD card directly to USB
sudo dd if=/dev/mmcblk0 of=/dev/sdb bs=4M status=progress conv=fsyncif=→ input file (the SD card you’re booted from)of=→ output file (the USB stick)bs=4M→ speeds up the copystatus=progress→ shows how far along it isconv=fsync→ flushes writes correctly
🕑 This will take a while depending on the card size.
4. Ensure all data is written
syncThis ensures the OS has finished writing to the USB stick.
5. Test the USB
When it’s done, unplug the USB stick and plug it into your target machine to boot from it.
It should be a bit-for-bit clone of your SD card.
6. (Optional) Expand filesystem
If your USB is larger than the SD card:
sudo growpart /dev/sdb 2sudo resize2fs /dev/sdb2This resizes the root partition to use all space.
✅ Summary of commands
lsblk # Find devicessudo umount /dev/sdX* # Unmount USBsudo dd if=/dev/mmcblk0 of=/dev/sdX bs=4M status=progress conv=fsyncsync # Flush writes(replace sdX with your actual USB device name!)
⚠️ Important Warning:dd overwrites the entire USB stick without confirmation. Make absolutely sure you use the correct of= device (the USB, not your system disk).