How to create a Bootable USB from ISO in Linux?

To create a bootable USB drive from an ISO file in Linux, we find it useful when installing a new operating system or running a live environment without affecting the existing system. It's also an excellent option when the computer lacks a CD/DVD drive, as USB drives are more common and easier to use.

The process involves identifying the USB device, obtaining the ISO file, and using command-line tools like dd to write the ISO directly to the USB drive. This creates a bit-for-bit copy that makes the USB drive bootable.

Step-by-Step Process

Step 1 Insert Your USB Drive

Insert the USB drive into the computer's USB port, ensuring it's pushed in until it clicks into place. Important: Back up any data on the drive, as this process will erase all existing content. The USB drive should be at least as large as the ISO file size.

Step 2 Find the Device Name

After inserting the USB drive, you need to identify its device name. In Linux, all devices are represented as files in the /dev directory. Open a terminal and use the lsblk command to list all connected block devices.

lsblk

The output will show all storage devices

NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda      8:0    0 232.9G  0 disk 
??sda1   8:1    0   487M  0 part /boot
??sda2   8:2    0  46.6G  0 part /
??sda3   8:3    0 185.7G  0 part /home
sdb      8:16   1   7.4G  0 disk 
??sdb1   8:17   1   7.4G  0 part /media/usb0

The USB drive typically appears as sdb, sdc, or similar. Note the device name (e.g., /dev/sdb) for later use.

Step 3 Download the ISO File

Download the ISO file for your desired Linux distribution from the official website. After downloading, verify the file's integrity using a checksum utility like md5sum or sha256sum to ensure it wasn't corrupted during the download process.

Step 4 Unmount the USB Drive (if mounted)

If the USB drive is automatically mounted, unmount it first to prevent conflicts during the writing process

sudo umount /dev/sdb1

Step 5 Write ISO to USB Drive

Use the dd command to write the ISO file directly to the USB drive. This creates a bootable USB by copying the ISO bit-for-bit

sudo dd if=/path/to/iso/file.iso of=/dev/sdb bs=4M status=progress && sync

Replace /path/to/iso/file.iso with your actual ISO path and /dev/sdb with your USB device name.

1096476672 bytes (1.1 GB, 1.0 GiB) copied, 47 s, 23.3 MB/s
261+1 records in
261+1 records out
1099512672 bytes (1.1 GB, 1.0 GiB) copied, 48.7658 s, 22.5 MB/s

The status=progress option shows transfer progress, and sync ensures all data is written before the command completes.

Step 6 Safely Remove the USB Drive

Once copying is complete, safely eject the USB drive to ensure all data has been written properly

sudo eject /dev/sdb

eject: /dev/sdb ejected

Alternative Methods

For users preferring graphical tools, applications like Balena Etcher, UNetbootin, or the built-in Startup Disk Creator (Ubuntu) provide user-friendly interfaces for creating bootable USB drives.

Important Safety Tips

• Double-check device names Using the wrong device can overwrite your hard drive

• Backup important data The USB drive will be completely erased

• Use appropriate permissions The dd command requires root privileges

• Verify ISO integrity Always check checksums before writing

Conclusion

Creating a bootable USB drive from an ISO file in Linux is a straightforward process using the dd command. The key steps are identifying the correct USB device, downloading and verifying the ISO file, and carefully writing the ISO to the USB drive. This method creates a reliable bootable drive for installing operating systems or running live environments.