layout: post title: ‘How to create a bootable USB memory stick from an ISO file, on RedHat 6’ —

Today I needed to make a bootable USB from an ISO image file, on my Red Hat Enterprise 6 (SLC6) machine. In particular, I had to install Ubuntu on my RedHat machine.

Here below the summary of all the steps:

1. Download the .iso file you need. (In my today’s example, I downloaded the most recent Ubuntu’s image file)

2. Attach a USB key. The USB key is usually auto-mounted and a Nautilus window will show you its content. The key will be erased, so remember to backup somewhere all the files stored in the USB stick. Notice the mount path; in my example it is:

    /media/KINGSTON
   

3. Check the name of the USB device:

    fdisk -l
   

   In my example, I get the device name /dev/sdc

4. Unmount the USB key with the terminal, NOT with Nautilus “Eject” (otherwise the dd command used on next steps will not see it properly):

    umount /media/KINGSTON
   

5. Copy the .iso file to the USB key (again: it will ERASE the USB key’s content!), using the path of the iso file as input and the device name of the USB stick as output; the bs value is optional but setting it to a large value speeds up the process:

    dd if=/downloads/ubuntu-14.04-desktop-amd64.iso of=/dev/sdc bs=512k
   

   a) You can check the bs values of the input iso file with:

    isoinfo -d -i /downloads/ubuntu-14.04-desktop-amd64.iso | grep size
    ...
    Logical block size is: 2048
   

   Set the bs option to a larger value than that listed above.

6. Wait for dd to finish writing the image to the USB memory stick. The process is completed when you get an output like this below, and the command-line prompt appears again:

    1928+0 records in
    1928+0 records out
    1010827264 bytes (1.0 GB) copied, 102.146 s, 9.9 MB/s
   

7. Log out from the root account and unplug the USB drive (which should be still unmounted).
8. The USB memory stick is now ready to be used as a bootable device.