Ubuntu CD and DVD images can now be written directly to a USB stick, which is a very easy way to make a bootable USB stick. Simply choose a CD or DVD image that will fit on your USB stick. See Section 4.1, “Official Ubuntu CD-ROMs” to get a CD or DVD image.

Alternatively, for very small USB sticks, only a few megabytes in size, you can download the mini.iso image from the netboot directory (at the location mentioned in Section 4.2.1, “Where to Find Installation Images”).

The CD or DVD image you choose should be written directly to the USB stick, overwriting its current contents. For example, when using an existing GNU/Linux system, the CD or DVD image file can be written to a USB stick as follows, after having made sure that the stick is unmounted:

# cp debian.iso /dev/sdX
# sync

The win32diskimager utility can be used under other operating systems to copy the image.

	Important
	The image must be written to the whole-disk device and not a partition, e.g. /dev/sdb and not /dev/sdb1. Do not use tools like unetbootin which alter the image.

	Important
	Simply writing the CD or DVD image to USB like this should work fine for most users. The other options below are more complex, mainly for people with specialised needs.

The hybrid image on the stick does not occupy all the storage space, so it may be worth considering using the free space to hold firmware files or packages or any other files of your choice. This could be useful if you have only one stick or just want to keep everything you need on one device.

Create a second, FAT partition on the stick, mount the partition and copy or unpack the firmware onto it. For example:

# mount /dev/sdX2 /mnt
# cd /mnt
# tar zxvf /path/to/firmware.tar.gz
# cd /
# umount /mnt

You might have written the mini.iso to the USB stick. In this case the second partition doesn't have to be created as, very nicely, it will already be present. Unplugging and replugging the USB stick should make the two partitions visible.

An alternative way to set up your USB stick is to manually copy the installer files, and also a CD image to it. Note that the USB stick should be at least 1 GB in size (smaller setups are possible if you follow Section 4.3.3, “Manually copying files to the USB stick — the flexible way”).

There is an all-in-one file netboot/boot.img.gz which contains all the installer files (including the kernel) as well as syslinux and its configuration file .

To use this image simply extract it directly to a partition on your USB stick:

# zcat boot.img.gz > /dev/sdX1

If you like more flexibility or just want to know what's going on, you should use the following method to put the files on your stick. One advantage of using this method is that — if the capacity of your USB stick is large enough — you have the option of copying any ISO image, even a DVD image, to it.

4.3.3.1. Partitioning the USB stick

We will show how to set up the memory stick to use the first partition, instead of the entire device.

Note

Since most USB sticks come pre-configured with a single FAT16 partition, you probably won't have to repartition or reformat the stick. If you have to do that anyway, use cfdisk or any other partitioning tool to create a FAT16 partition[2], install an MBR using: # install-mbr /dev/sdX The install-mbr command is contained in the mbr Ubuntu package. Then create the filesystem using: # mkdosfs /dev/sdX1 Take care that you use the correct device name for your USB stick. The mkdosfs command is contained in the dosfstools Ubuntu package.

In order to start the kernel after booting from the USB stick, we will put a boot loader on the stick. Although any boot loader (e.g. lilo) should work, it's convenient to use syslinux, since it uses a FAT16 partition and can be reconfigured by just editing a text file. Any operating system which supports the FAT file system can be used to make changes to the configuration of the boot loader.

To put syslinux on the FAT16 partition on your USB stick, install the syslinux and mtools packages on your system, and do:

# syslinux /dev/sdX1

Again, take care that you use the correct device name. The partition must not be mounted when starting syslinux. This procedure writes a boot sector to the partition and creates the file ldlinux.sys which contains the boot loader code.

default vmlinuz initrd=initrd.gz