1. You must download UNetbootin to install ubuntu inside the USB. UNetbootin allows for the installation of various Linux/BSD distributions to a partition or USB drive, so it’s no different from a standard install, only it doesn’t need a CD. It can create a dual-boot install, or replace the existing OS entirely. You can download the Linux version if you’re running on Linux, and you can download the Windows version if you’re using windows.
Choose Ubuntu For Your OS or you can input the disk image(ISO), even the floppy drive
chmod +x ./unetbootin-linux, or going to Properties->Permissions and checking “Execute”), then start the application, you will be prompted for your password to grant the application administrative rights, then the main dialog will appear, where you select a distribution and install target (Hard Disk or USB Drive), then reboot when prompted. See this screenshot:
All thing looks the same, the differences is only the USB Drive directory as you can see it will changed into /dev/sdc1 or sdc2 and other.
3. After the Installation
After the installation, just simply reboot your PC and hit f8 and choose the USB driver and it will boot automatically into Ubuntu.
If using Windows, UNetbootin should prompt you to remove it the next time you boot into Windows. Alternatively, you can remove it via Add/Remove Programs in the Control Panel.
If using Linux, re-run the UNetbootin executable (with root priveledges), and press OK when prompted to uninstall.
Removal is only required if you used the “Hard Drive” installation mode; to remove the bootloader from a USB drive, back up its contents and reformat it.
Uninstalling UNetbootin simply removes the UNetbootin entry from your boot menu; if you installed an operating system to a partition using UNetbootin, removing UNetbootin will not remove the OS.
To manually remove a Linux installation, you will have to restore the Windows bootloader using “fixmbr” from a recovery CD, and use Parted Magic to delete the Linux partition and expand the Windows partition.
5. Installation Problem Solve
If you encounter some errors with UNetbootin, you can post a question on the Ubuntu Forums, on either the LiveUSB installation thread or Hard disk installation thread depending on your install mode, or file a bug report. However, if it’s a distribution or hardware-specific issue, file a bug report against the distribution itself. You also can ask the IRC if you are still experiencing a trouble.