When you are trying to write live USB images of Ubuntu based distros, you’ll need to mount your USB device in a mount point as /media/pendrive/. With tools like UNetBootin you’ll get a message like this:
You must first mount the USB drive /dev/sdb1 to a mountpoint.
So, while you don’t mount your USB device, you cannot proceed with you disk installation. Then, it’s so easy to fix this, you only need do this step before:
[bash]sudo mkdir /media/pendrive/[/bash]
Next, mount your device to this folder:
[bash]sudo mount -t vfat /dev/sdb1 /media/pendrive[/bash]
Now, use your prefered tool to write your live USB disk. Here I’m using Unetbootin:
[bash]chmod +x ~/Downloads/unetbootin[/bash]
[bash]sudo /bin/sh ~/Downloads/unetbootin[/bash]
It’s done, now just umount your device and install your unix OS.
If you want know more about advanced mount options, you can access the Help Wiki on link below: