2 Ways to Create an ISO from a Bootable USB in Linux

In this article, we will show you how to create an ISO from a bootable USB drive in Linux. We will explain two ways to achieve this: via the command line interface (CLI) and a graphical user interface (GUI) program.

Create An ISO From A Bootable USB Drive Using dd Tool

dd is a commonly used command-line tool for Linux and other Unix-like operating systems, used to convert and copy files.

To create an ISO image from a Bootable USB Drive files, first you need to insert your USB drive and then find the device name of your USB using following df command.

$ df -hT
Sample Output
Filesystem     Type      Size  Used Avail Use% Mounted on
udev           devtmpfs  3.9G     0  3.9G   0% /dev
tmpfs          tmpfs     787M  1.5M  786M   1% /run
/dev/sda3      ext4      147G   28G  112G  20% /
tmpfs          tmpfs     3.9G  148M  3.7G   4% /dev/shm
tmpfs          tmpfs     5.0M  4.0K  5.0M   1% /run/lock
tmpfs          tmpfs     3.9G     0  3.9G   0% /sys/fs/cgroup
/dev/sda1      vfat      299M   11M  288M   4% /boot/efi
tmpfs          tmpfs     787M   56K  787M   1% /run/user/1000
/dev/sda5      ext4      379G  117G  242G  33% /media/tecmint/Data_Storage
/dev/sdb1 iso9660 1.8G 1.8G 0 100% /media/tecmint/Linux Mint 19 Xfce 64-bit

From the output above, you can clearly see that our attached USB device name is /dev/sdb1.

Now you can run the following command to create an ISO from a bootable USB drive as shown. Make sure to replace /dev/sdb1 with your USB drive and /home/tecmint/Documents/Linux_Mint_19_XFCE.iso with the full name of the new ISO image.

$ sudo dd if=/dev/sdb1 of=/home/tecmint/Documents/Linux_Mint_19_XFCE.iso

In the above command, the option:

  • if – means read from specified FILE instead of stdin.
  • of – means write to specified FILE instead of stdout.

Once done, you can verify the ISO image using following ls command as shown.

$ ls -l /home/tecmint/Documents/Linux_Mint_19_XFCE.iso
Create ISO from Bootable USB Using dd Command
Create ISO from Bootable USB Using dd Command

Create An ISO From A Bootable USB Drive Using Gnome Disks

Gnome Disks is a graphical tool used to manage disk drives and media in Linux. It is used to format and partition drives, mount and unmount partitions, and query S.M.A.R.T. (Self-Monitoring Analysis and Reporting Technology) attributes.

If you don’t have gnome-disk utility on your system, you can install it by running the following command.

$ sudo apt install gnome-disk-utility        #Ubuntu/Debian
$ sudo yum install gnome-disk-utility        #CentOS/RHEL
$ sudo dnf install gnome-disk-utility        #Fedora 22+

After successfully installing Gnome disk, search and open it from the system menu or dash. Then from the default interface, select the bootable device from the list of mounted devices on the left-hand pane, by clicking on it and click on disk options. Then click on Create Disk Image option as shown in the following image.

Create a Disk Partition Image
Create a Disk Partition Image

From the dialog window, set the name of the ISO file, its location and click Start creating. Then enter your password to open the bootable device and the process should start if the authentication is successful.

Create ISO from Bootable USB Using Gnome Disks
Create ISO from Bootable USB Using Gnome Disks

That’s it for now! In this article, we’ve explained two ways to create an ISO from a bootable USB drive in Linux. Use the comment form below to share your thoughts with us or ask questions.

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23 thoughts on “2 Ways to Create an ISO from a Bootable USB in Linux”

  1. Can I use this method to say, boot a Debian-live.iso (text only NO DE) from a USB stick, install software; e.g, a windows manager + some apps, then use this approach to save that and the resulting file will be a bootable custom.iso?

    Reply
    • Hi Moltke, No, a Live iso uses a squash.file that can not be modified without the special procedure of decompressing squash file – build OS – rebuild squash (very complicated). To build a custom OS USB build.iso with Debian or what I use Sparkylinux 5 to a USB stick,

      1. Gparted –> USB Stick = 1 partition ext4 & 1 partition swap (2-4GB usually).
      2. Make a deb or sparky live DVD, boot from DVD, and then insert USB stick 16GB at least.
      3. Install OS to /dev/sdX1 partition (X is identifying number for your USB stick).
      4. Customize your USB bootable OS.
      5. Use the above to create the iso file.
      6. Compress the iso with xz (it will reduce the size to about 1/2 in most instances).

      Hope this helps!

      Reply

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