Linux Create A Bootable USB Pen

You need to format your USP pen device as Win FAT32. Once formatted type the following commands to make it bootable.

Our Device Names

1. USB Pen Device Name : /dev/sdb1
2. DVD Mount : /media/cdrom0
3. USB Mount Point : /media/usb
4. USB File System : Win FAT32
5. ISO or DVD Image : Fedora / CentOS / RHEL

To find information about your devices and current partitions run:
# dmesg | less
# dmesg | egrep -i 'cd|dvd'
# fdisk -l
Use the first command to identify the USB device name.

Mount CD/DVD ISO or DVD ITSELF

Type the following command to mount Fedora 12 iso image:
# mount Fedora-12-x86_64-netinst.iso -o loop /media/cdrom0/
# DVD=/media/cdrom0
# ls -l $DVD
Sample outputs:

total 6
dr-xr-xr-x 3 root root 2048 2009-11-09 05:37 EFI
drwxr-sr-x 3 root  499 2048 2009-11-09 05:37 images
drwxr-sr-x 2 root  499 2048 2009-11-09 05:36 isolinux

You need to use files stored in isolinux directory to create a bootable usb pen.

Format Usb

Create the fdisk partition:
# fdisk /dev/sdb
You need to create only 1 partition. Next format the partition:
# USB=/media/usb
# mkdosfs /dev/sdb1
Finally mount the partition:
# mkdir -p /media/usb
# mount /dev/sdb1 /media/usb
# USB=/media/usb

Copy Required Files

Type the following commands:
# cp -av $DVD/isolinux/* $USB
# cd $USB
# rm isolinux.bin boot.cat TRANS.TBL
# mv isolinux.cfg syslinux.cfg

Also copy the installer's initial RAM disk $DVD/images/pxeboot/initrd.img (for CentOS / RHEL Linux use $DVD/RedHat/images/pxeboot/initrd.img file) CD/DVD onto the usb drive:
# cp -v $DVD/images/pxeboot/initrd.img $USB

Unmount the USB drive

# umount /dev/sdb1

Make the USB Bootable

Type the following command to make the USB drive bootable
# syslinux /dev/sdb1
# mount /dev/sdb1 $USB
syslinux is a boot loader for the Linux operating system which operates off an MS-DOS/Windows FAT filesystem.

Install Grub

Type the following command to install GRUB on the USB device:
# grub-install --root-directory=$USB /dev/sdb
Create grub.conf:
# cd $USB
# mkdir -p boot/grub
Edit the grub.conf file

default=0
timeout=5
root (hd1,0)
title Fedora Linux
kernel /vmlinuz
initrd /initrd.img

Finally, unmount the USB pen drive, enter:
# umount /dev/sdb1
Your USB pen is ready and should be bootable from the USB device. This can be used to install Fedora or CentOS or RHEL. You can also copy other required tools (such as sniffers or data recovery tools) on this pen. This is left as exercise for the reader.

Unetbootin Installer of Linux/BSD Distributions (GUI Tools)

If command line options are too complicated to follow. Try UNetbootin, which allows you to create bootable Live USB drives for a variety of Linux distributions from Windows or Linux, without requiring you to burn a CD. To install to a partition or USB drive type the following command:
$ sudo apt-get install unetbootin