Revision 39 as of 2007-03-09 01:08:27

Clear message


It is possible to have Ubuntu or Kubuntu on a USB pendrive or USB hard disk drive with persistent mode. This means that you can boot from a USB pendrive and keep customisations such as keyboard layout, numlock, preferences, additional packages saved on the pendrive. This can be done using linux or windows. You will need a USB pendrive of 1 GB or more. This page is written after having tested the instructions on a Peak III 1 GB pendrive. The preparation of the pendrive is explained using 'fdisk' because I had errors with 'gparted' and i could not give the partitions a volume name. I used Ubuntu to make the pendrive. In Kubuntu it is more or less the same. Where you see 'ubuntu' replace it by 'kubuntu'. I will mark the other differences.

Installing Ubuntu on USB pendrive using Linux

Preparing the USB pendrive

Making partitions

The preparation of the pendrive is explained using 'fdisk'. You could use 'gparted' or 'qtparted' as well. However I had errors with 'gparted' and I could not give the partitions a volume name. I tested 'qtparted' as well and it worked fine. You can install 'qtparted' under Ubuntu through synaptic although it is native to Kubuntu. Another issue in my case was that 'fdisk' recognised a fat32 filesystem as linux. So I checked it with gparted and it was OK.

Plug in the pendrive and check its device name :

sudo fdisk -l

We are going to suppose that its name is /dev/sdX where X is the disk device such as /dev/sda or /dev/sdc. Please be sure to use the correct number for X which matches the name you find for your pen drive. Double check it ! [Note: on newer computers, which use serial ATA disks, /dev/sda is typically the main hard drive; do not overwrite this!]

Now we are going to create 2 partitions : 1 partition of 700 MB with a fat32 filesystem and 1 partition with the rest of the pendrive space with volume name "casper-rw" and ext2 filesystem. The first partition will be made active.

Go in terminal and unmount the drive :

sudo umount /dev/sdX1

Fire up fdisk for the pendrive :

sudo fdisk /dev/sdX

This will give you the fdisk prompt. Look to what you have on the pendrive. Check if you have to backup the data you have on it. 'p' will print the content of /dev/sdX. If you have partitions on it remove them ('d', 'partition number'). Make partition 1 : 'n' for new partition, 'p' to make it a primary partition, '1' to call it partition number 1, then just press enter to accept the proposed starting cylinder, '+700M' to make its size 700 MB. Then 'a' to make it the active partition. Set the file system of partition 1 to FAT: 't', then '1', then '6'. Make partition 2 : 'n' for new partition, 'p' to make it a primary partition, '2' to call it partition 2, then just press enter to accept the proposed starting cylinder, then press enter to accept the proposed ending cylinder. Save and quit fdisk with 'w' to write the new settings.

I had an issue with this that every time I saved my partition setup using 'w', I'd get an:

WARNING: Re-reading the partition table failed with error22: Invalid argument. The kernel still uses old table. The new table will be available at the next reboot.

If this happens, and then checking with 'sudo fdisk -l' doesn't show the new partitions - here's a fix if you have a Windows OS, though I don't know why it works:

Do nothing else with the pendrive. Insert into Windows (mine was XP) and format with Disk Management and use FAT32. Now, 'sudo fdisk -l' should see the two partitions under the pendrive. -neverard

Check the result : sudo fdisk -l You should see the 2 partitions with the first marked with a * because it is active.

If ubuntu mounted the partitions again you should unmount them:

sudo umount /dev/sdX1
sudo umount /dev/sdX2

for me +700M wasn't enough, i needed +750M, also make sure (via fdisk -l) you created a w95/fat and not a linux partition, otherwise i was unable to boot from it !! (i had to use gparted to achieve this) - bernstein fdisk worked for me however - booted off CD - krishnan

Formatting the partitions

We will now format the partitions by putting a filesystem on and giving them the name 'edgy' (or any other name you want) and 'casper-rw' (this name is MANDATORY, do not change other names and do not use capital letters) :

sudo mkfs.vfat -F 32 -n edgy /dev/sdX1
sudo mkfs.ext2 -b 4096 -L casper-rw /dev/sdX2

Mount the partitions on the pendrive. Take out the pendrive and put it back. Ubuntu Dapper or Edgy will mount the pendrive automatically if you have checked this option under System -->Preferences--> Removable media. Otherwise use 'mount' :

sudo mount /dev/sdX1 /media/mountpointyouhave1
sudo mount /dev/sdX2 /media/mountpointyouhave2

Installing Dapper or Edgy on the USB pendrive

Download the dapper or edgy image (ubuntu-6.06-desktop-i386.iso or ubuntu-6.10-desktop-i386.iso) or put in the install CD if you have it. If you use the downloaded image you can access it as follows (supposing that the image is in the path you are working in; use 6.06 for dapper or 6.10 for edgy):

mkdir ubuntuCD
sudo mount ubuntu-6.06-desktop-i386.iso ubuntuCD -o loop

Now put in the CD or open the 'ubuntuCD' and make sure that you see the hidden files too. (verify if View-->Show Hidden Files is checked).

Copy the following folders and files to the 1st partition of your USB pendrive :

Folders : 'casper', 'disctree', 'dists', 'install', 'pics', 'pool', 'preseed', '.disk'

Files : all files from the folder 'isolinux', 'md5sum.txt', 'README.diskdefines', 'ubuntu.ico'

So you do not copy the folder 'isolinux' on the pendrive but only its contents directly in the root of the first partition of the pendrive.

Copy 'casper/vmlinuz', 'casper/initrd.gz', 'install/mt86plus'. So you will have these files double on the pendrive : once in the root '/' of the partition and once in the folder 'casper' or 'install'.

Rename the file 'isolinux.cfg' to 'syslinux.cfg' either by right clicking on it and selecting 'rename' or in terminal :

Replace /media/edgy to /media/whatmountpointyouhave1 if it's different

cd ubuntuCD
cp -rf casper /media/edgy
cp -rf disctree /media/edgy
cp -rf dists /media/edgy
cp -rf install /media/edgy
cp -rf pics /media/edgy
cp -rf pool /media/edgy
cp -rf preseed /media/edgy
cp -rf .disk /media/edgy
cp isolinux/* /media/edgy
cp md5sum.txt /media/edgy
cp README.diskdefines /media/edgy
cp ubuntu.ico /media/edgy
cp casper/vmlinuz /media/edgy
cp casper/initrd.gz /media/edgy
cp install/mt86plus /media/edgy
cd /media/edgy
mv isolinux.cfg syslinux.cfg

You don't need to copy the symlinked folders over (/dists/stable, /dists/unstable, /ubuntu) - bernstein

Making the pendrive bootable

We are going to install the linux bootloader 'syslinux'. This bootloader needs a configuration file which is 'syslinux.cfg'. This is the file we just made by renaming 'isolinux.cfg' from the installCD. However we have to modify this file. Open the file 'syslinux.cfg' from the pendrive with your favorite texteditor. For instance :

gedit syslinux.cfg

Adapt the content until you get this :

DEFAULT custom
GFXBOOT bootlogo
APPEND   preseed/file=preseed/ltsp.seed boot=casper initrd=initrd.gz ramdisk_size=1048576 root=/dev/ram rw quiet splash --
LABEL custom
  menu label ^Start Ubuntu in persistent mode
  kernel vmlinuz
  append  preseed/file=preseed/ltsp.seed boot=casper persistent initrd=initrd.gz ramdisk_size=1048576 root=/dev/ram rw quiet splash --
LABEL live
  menu label ^Start or install Ubuntu
  kernel vmlinuz
  append  preseed/file=preseed/ltsp.seed boot=casper initrd=initrd.gz ramdisk_size=1048576 root=/dev/ram rw quiet splash --
LABEL xforcevesa
  menu label Start Ubuntu in safe ^graphics mode
  kernel vmlinuz
  append  preseed/file=preseed/ltsp.seed boot=casper xforcevesa initrd=initrd.gz ramdisk_size=1048576 root=/dev/ram rw quiet splash --
LABEL check
  menu label ^Check CD for defects
  kernel vmlinuz
  append  boot=casper integrity-check initrd=initrd.gz ramdisk_size=1048576 root=/dev/ram rw quiet splash --
LABEL memtest
  menu label ^Memory test
  kernel mt86plus
  append -
  menu label ^Boot from first hard disk
  localboot 0x80
  append -
DISPLAY isolinux.txt
F1 f1.txt
F2 f2.txt
F3 f3.txt
F4 f4.txt
F5 f5.txt
F6 f6.txt
F7 f7.txt
F8 f8.txt
F9 f9.txt
F0 f10.txt

The menu choice called 'Custom' was made the default so that when booting up you can just hit Enter to start your customized session.

The essential difference is that the kernels and initrds have been moved out of the casper directory. Thus 'casper/initrd.gz' becomes 'initrd.gz'. Likewise for 'vmlinuz'.

You can also copy and paste this text as making a new file 'syslinux.cfg'. Kubuntu difference : text editor 'kwrite' instead of 'gedit'. Kubuntu difference : replace 'preseed/ltsp.seed' by 'preseed/kubuntu.seed'. Edgy difference: replace 'preseed/ltsp.seed' by 'preseed/ubuntu.seed'.

The last thing to do is installing the bootloader. Check if you have the 'syslinux' and 'mtools' package installed. If not install it ('sudo synaptic' and select from the package list or use 'apt-get').

First you need to unmount your usb stick :

cd ~
sudo umount /dev/sdX1

This command will install the bootloader on your pendrive :

syslinux /dev/sdX1

don't know why, but i had to use the -f switch (syslinux -f /dev/sda1) - bernstein ( same here - I had to use the -f switch - krishnan

syslinux complained it couldn't create LDLINUX.SYS, but it worked in the Windows version (see below) - JanSchlüter

If you get the error:

sh: mcopy: command not found
syslinux: failed to create ldlinux.sys

then you will need to install the mtools package.

Reboot on the pendrive, change some settings, reboot again and check if the changes are kept (persistence check).

So that is it.

Do not forget to check if the computer you are going to use the pendrive on boots USB devices first (look in BIOS settings). Enjoy (k)ubuntu whereever you go.

Installing Ubuntu on USB pendrive using Windows

Preparing the USB pendrive

Download a copy of the [ HP format utility] for USB drives, this utility makes it as easy to format USB pen drives as it is to format floppies.

Plug in your USB pen drive and use the HP format utility to format it with a FAT32 filesystem.

Using a partitioning tool, create two partitions. The first is formatted with a FAT32 filesystem and needs to be about 650 MB. The second should occupy the remaining free space and should be formatted with the ext2 filesystem and is given the name "casper-rw". Note! Most DOS partitioning tools will create the partition name in uppercase (CASPER-RW). Since Linux is case-sensitive you need to do the formatting of the second partition in Linux. The persistent feature will not work if the partition name is in uppercase. See the Wiki for details.

Installing Dapper or Edgy on the USB pendrive

This is the same as described in the Linux section except for accessing the downloaded image. The way to do this is to mount the iso image file and copy the files that way. You can do this with NERO or [ Windows VirtualCD]. You might want to do it this way if you don't want to burn a CD.

Making the pendrive bootable

Go to and download a copy of for Windows. Extract the zip file contents and move the extracted folder to your favorite location on your hard drive.

Open WordPad and edit the file syslinux.cfg as described in the Linux section.

Open a command prompt and change directory to the location of the syslinux folder. For example, if you placed the folder on your desktop then: cd C:\Documents and Settings\(your user name)\Desktop\syslinux-3.11\win32 (by the way you DO know that command prompt has command completion just like in Linux (start entering characters and then press the TAB key to complete the entry)).

Next write the bootsectors to the flash drive by entering the following command: syslinux -f X: --> where X: is replaced by the drive letter of your USB key. Be careful to pick the correct drive letter!


  • Some links in this page are broken (the long URLs are broken with ellipses).
  • If you want to install the test releases of Edgy Eft, you might want to look at CustomizedInitrd.

  • As syslinux does not support the "GFXBOOT" command the boot menu will lack some features, e.g. you cannot change the language before booting. You can specify a language and keyboard layout via kernel parameters, though. To boot into a German LiveCD environment, you would add the following to your "APPEND" lines in syslinux.cfg:

    locale=de_DE bootkbd=de console-setup/layoutcode=de console-setup/variantcode=nodeadkeys
  • Some USB keys don't have a master boot record. In these cases, the problem can usually be fixed by running

    lilo -M /dev/sdX

    I had to do this to get it to boot - Krishnan

  • Alternatively, if you haven't got lilo installed, use the 'install-mbr' command from the 'mbr' package:

    sudo apt-get install mbr
    sudo install-mbr /dev/sdX

    -JohnMccreesh I could not get mbr to install, but lilo worked - krishnan

  • This may be my fault, but I created a Persistent pen drive from Ubuntu using these instructions and it worked perfectly, but I had installed an Edgy Beta, when I decided to update it to the final only a windows machine was available, follwing the windows instructions ( minus partitioning as that was still there from the previous install ) I do not get the normall Ubuntu prompt with a "custom" option at the top like before, instead I get a prompt with "Boot:" and I have to enter vmlinuz to boot, if I just hit return Ubuntu boots but something fails and it drops into a recovery console. Could somebody confirm that the windows directions are correct ( my suspicion is that it is because in Ubuntu you are using Ubuntu's custom version of syslinux while in windows you are using the "vanilla" version ) Also, the direction on where to find syslinux could be clearer, I found them at with no indication that the .zip file was indeed for windows, I tried the newest version at that time: and the exact version mentioned in the instructions both gave the same result -Jordan U

    • I successfully installed Edgy (final) to an USB drive, following the linux instructions but using syslinux-3.20 for Windows. Afterwards I installed GRUB in the MBR which also works fine. -JanSchlüter

      • I ran syslinux from Ubuntu on the same drive changing nothing else and it worked, I honestly don't know what went wrong with the windows version. Can you confirm that when you installed from windows it not only booted but correctly showed the menu with the preconfigured options, "custom" "live" "memtest" etc ? - Jordan U.
        • In my installation I can still use GRUB to load syslinux. Syslinux displays the ubuntu logo and a command prompt. I can enter memtest to boot Memtest86+ or press return to boot the ubuntu live environment. I didn't use the windows version of syslinux only, though - I tried ubuntu's version first which failed to create LDLINUX.SYS, then I tried the windows version. Maybe it only works in combination... -JanSchlüter

I (successfully) made a USB boot drive using these instruction and later saved the working partitions because I needed the drive for another purpose - on restoring the partitions and running syslinux again I couldn't get my drive to boot - after many hours of head-scratching and re-installing I found that the boot flag wasn't set! Just be aware that sometimes simple things can trip you up.. David C. - Just a thanks to all that contributed - Krishnan