How To Create Bootable USB Drive Using dd Command

Creating a bootable USB drive is a crucial task for installing or repairing operating systems. While there are many GUI tools like Rufus or BalenaEtcher, Linux users have a powerful alternative: the dd command. It’s fast, reliable, and available by default on most Unix-based systems.

This guide walks you through the steps to create a bootable USB using the dd command from the terminal.

⚠️ Disclaimer

The dd command is very powerful and does not warn before overwriting data. Be extra cautious when specifying the destination drive, or you could lose important data.

Step-by-Step Guide

Step 1: Insert Your USB Drive

Plug in your USB drive. It should be at least 4GB for most modern ISO images.

Step 2: Identify Your USB Drive

Open a terminal and run:

lsblk

Look for your USB drive (usually /dev/sdb or /dev/sdc). Do not use partitions like /dev/sdb1 — you need the whole device.

Example output:

NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda      8:0    0  120G  0 disk
├─sda1   8:1    0  100G  0 part /
└─sda2   8:2    0   20G  0 part [SWAP]
sdb      8:16   1   8G   0 disk

In this example, the USB is /dev/sdb.

Step 3: Unmount the USB Drive

If it’s automatically mounted, unmount it using:

sudo umount /dev/sdb*

Step 4: Write the ISO to USB Using dd

Now use the dd command. Replace input.iso with the path to your ISO file, and /dev/sdX with your USB drive (e.g., /dev/sdb).

sudo dd if=/path/to/input.iso of=/dev/sdX bs=4M status=progress oflag=sync

Explanation:

• if=: input file (your ISO)
• of=: output file (your USB device)
• bs=4M: read/write in 4MB chunks for faster speed
• status=progress: shows ongoing status
• oflag=sync: ensures data is written properly

Example:

sudo dd if=ubuntu-22.04.iso of=/dev/sdb bs=4M status=progress oflag=sync

Step 5: Wait for Completion

This process may take a few minutes. Wait until the terminal returns to prompt. Do not remove the USB during this process.

Step 6: Safely Eject the USB

Once done, flush any remaining cache:

sync

Now remove your USB safely.

Conclusion

Using the dd command to create a bootable USB is a reliable and quick method for Linux users. Just be sure you double-check the destination device to avoid overwriting valuable data. Whether you’re installing Ubuntu, Fedora, or Arch, this method works across all major distros.