Create a Bootable USB Using dd Command in Linux

Last Updated on 6 days by Sachin G

In this guide, I’ll show you how to create a bootable USB using the dd command in Linux. i’ll cover everything step by step, with examples and pro tips to avoid common mistakes.

Creating a bootable USB is one of those essential skills every Linux user eventually needs. Whether you’re installing a fresh Linux distribution, testing out new operating systems, or preparing recovery tools, having a reliable bootable USB drive is a lifesaver. Over the years, I’ve tried several tools like Rufus, Etcher, and Unetbootin, but I keep coming back to the simplicity and power of the dd command in Linux.

Unlike GUI-based tools, dd is fast, reliable, and works in any Linux terminal without extra installation. It may look intimidating at first glance, but trust me—once you understand it, you’ll never go back.

Why Use dd to Create a Bootable USB?

Before diving into commands, let’s understand why dd is such a popular choice among Linux professionals.

• Pre-installed on Linux: Most Linux distributions come with dd already installed. No extra downloads.
• Lightweight & Fast: Unlike GUI tools, dd works directly in the terminal without overhead.
• Works Everywhere: It’s universal for all Linux flavors—Ubuntu, Debian, Fedora, Arch, you name it.
• Low-level Copying: It writes the ISO image bit by bit, ensuring a perfect replica.

Note: dd is powerful but dangerous if misused. A wrong device name can wipe your entire disk. I’ll share safety tips later.

Prerequisites Before Using dd

Before we start, make sure you have the following:

• A Linux machine (Ubuntu, Fedora, Debian, or any distro).
• A USB drive (at least 4GB for most Linux ISOs).
• The ISO image of the OS you want to install (e.g., Ubuntu 24.04 LTS).
• Sudo privileges (required for writing to USB).

Step 1: Download the ISO File

First, you need to download an ISO file of the Operating System. ISO File you can get from the official website of the OS provider. It can be Ubuntu, CentOS, AlmaLinux, Rocky Linux, or Oracle Linux. Some of the Linux-based distros’ official operating system page URL is below. 

• For Ubuntu 
• For Fedora 
• For AlmaLinux

After downloading the iso image file, you should keep the path of the downloaded ISO image file and also format the USB drive.

Step 2: Identify Your USB Device

This step is crucial to avoid data loss. When you attach the USB drive then it can be mounted automatically. First, check and review information about the USB device through the commands below.

lsblk

This lists all block devices. Plug in your USB drive and run lsblk again. The new device that appears is your USB drive.

Example output:

Here, sdb is the USB device (without the number). Never confuse this with your main disk (usually sda)!.

Step 3: Unmount the USB Drive

If the USB is mounted, unmount it before writing the ISO. If the device is mounted under the “ MOUNTPOINTS or Mounted on “, then you unmount it through the umount command.

Replace sdb with your actual device name.

Step 4: Create a Bootable USB Using dd Command

First, find a USB  and keep storing data backup, which is in a USB stick and insert it into your system. Creating an image on a USB flash drive with the dd command is a very simple step. First, find the device path associated with the USB drive. Assuming it’s /dev/sdb. Be careful if sdb is a block store with data, these commands will overwrite all data on that device.

sudo dd if=~/Downloads/ubuntu.iso of=/dev/sdb bs=4M status=progress

Explanation:

• if= → Input file (ISO image)
• of= → Output device (USB)
• bs=4M → Block size (speeds up copying)
• status=progress → Shows progress bar

In the above command, you can also use the progress option to get status . status=progress. After the process gets complete, now your USB stick is ready for boot. 

Now you can use a USB drive for installation.

Pro Tips for Safe Usage

• Triple-check the device name (/dev/sdb). Wrong disk = total data loss.
• Use sync after the command finishes to ensure all data is written:

Step 5: Verify the Bootable USB

After completion, eject the USB:

sudo eject /dev/sdb

You can now plug it into any machine and boot from it.

Common Errors and Fixes

❌ “Permission denied”

Solution: Use sudo before the command.

❌ USB not booting

• Ensure you wrote the ISO to the device (/dev/sdb), not a partition (/dev/sdb1).
• Check if the ISO is a hybrid image (most Linux ISOs are).

Alternative: Monitor Write Speed

Want to see write speed? Use:

sudo dd if=~/Downloads/ubuntu.iso of=/dev/sdb bs=4M status=progress conv=fsync

Why dd Over GUI Tools?

I’ve used tools like Etcher and UNetbootin, but dd always wins when:

• Working on remote servers over SSH
• Minimal systems without GUI
• Faster write with fewer errors

Best Practices

• Always backup USB data before writing.
• Download ISO from official sources only.
• Run sha256sum to verify ISO integrity:

sha256sum ~/Downloads/ubuntu.iso

FAQs

Creating a bootable USB using the dd Command in Linux might look daunting at first, but it’s one of the most reliable and universal methods out there. With just a single command, you can transform any USB drive into a powerful installation media for Linux distributions.

Sachin G

I’m Sachin Gupta — a freelance IT support specialist and founder of techtransit.org. I’m certified in Linux, Ansible, OpenShift (Red Hat), cPanel, and ITIL, with over 15 years of hands-on experience. I create beginner-friendly Linux tutorials, help with Ansible automation, and offer IT support on platforms like Upwork, Freelancer, and PeoplePerHour. Follow Tech Transit for practical tips, hosting guides, and real-world Linux expertise!

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