Reference
https://fedoraproject.org/wiki/How_to_create_and_use_Live_USB
Download "Fedora-12-i686-Live.iso".
http://download.fedoraproject.org/pub/fedora/linux/releases/12/Live/i686/Fedora-12-i686-Live.iso
Mount it to /mnt (instead of burn it into CD)
root@ang-laptop:/$ mount -o loop /home/ang/FedoraSetup/Fedora-12-i686-Live.iso /mnt/iso
Check the inserted USB thumb drive's device node
root@ang-laptop:/mnt/iso# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda2 102452552 73206136 24042040 76% /
udev 1548200 308 1547892 1% /dev
none 1548200 188 1548012 1% /dev/shm
none 1548200 188 1548012 1% /var/run
none 1548200 0 1548200 0% /var/lock
none 1548200 0 1548200 0% /lib/init/rw
/dev/loop0 3129324 3129324 0 100% /mnt/mnt-dvd
/dev/sdb1 15116836 867984 13480948 7% /media/LinuxOS
root@ang-laptop:/mnt/iso#
Use "livecd-iso-to disk" utilities to expand iso into thumb drive
root@ang-laptop:/mnt/iso/LiveOS$ cd ./mnt/iso/LiveOS
root@ang-laptop:/mnt/iso/LiveOS$ ./livecd-iso-to-disk /home/ang/FedoraSetup/Fedora-12-i686-Live.iso /dev/sdb1
Verifying image...
./livecd-iso-to-disk: line 399: checkisomd5: command not found
Are you SURE you want to continue?
Press Enter to continue or ctrl-c to abort
/dev/sdb1 is mounted, please unmount for safety
Cleaning up to exit...
OOps...then we umount it first
root@ang-laptop:/mnt/iso/LiveOS$ umount /dev/sdb1
root@ang-laptop:/mnt/iso/LiveOS$ ./livecd-iso-to-disk /home/ang/FedoraSetup/Fedora-12-i686-Live.iso /dev/sdb1
Verifying image...
./livecd-iso-to-disk: line 399: checkisomd5: command not found
Are you SURE you want to continue?
Press Enter to continue or ctrl-c to abort
Copying live image to USB stick
Updating boot config file
Installing boot loader
/media/usbdev.mWbVUH/syslinux is device /dev/sdb1
USB stick set up as live image!
root@ang-laptop:/mnt/iso/LiveOS$