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— because if it was easy, everyone would do it

  • Credits : John S and John C

Coding is one of the highest art forms achieved by mankind; an idea - just an electrical impulse - is made real in an alternate electronic universe; the created idea however, does not have physical form, and yet can change the physical world; it cannot be touched, and yet may touch all mankind.

How to make a bootable linux USB 'disk'

There are several ways to do this. The method shown here is the simplest one I've ever seen.

At the heart of this process is this command:

livecd-iso-to-disk --format --reset-mbr /path_to/Live_DVD.iso /dev/sdX

This tells the program livecd-iso-to-disk to create a bootable file system using a downloaded ISO file on the USB device /dev/sdX.

1 Download a live CD or DVD image of the Linux distribution you prefer. In this example I'm using Fedora 17, x86_64 architecture. You can get a suitable ISO file from here.

2 Next you'll need to install the package livecd-tools. If you try to do this when you're not root you'll get this error:

bash-4.2$ yum install livecd-tools
Loaded plugins: langpacks, presto, refresh-packagekit
You need to be root to perform this command.

Switch user to root and re-issue the command.

bash-4.2$ su -
Password: 
[root@cobh ~]# yum install livecd-tools

3 Now change directory to where you saved the downloaded ISO image file, and use ls to get the full name of the downloaded file.

[root@cobh ~]# cd /home/username/Downloads
[root@cobh Downloads]# ls -l
total 660484
-rw-r--r-- 1 username domainusers 676331520 Oct 11 09:41 Fedora-17-x86_64-Live-Desktop.iso

4 Now find out the name of your USB device. Plug it in, wait a moment and then use df to identify your device name.

[root@cobh Downloads]# df -h
Filesystem            Size  Used Avail Use% Mounted on
rootfs                 32G  9.1G   21G  31% /
/dev/sda3             497M   90M  383M  20% /boot
//server/public       805G  556G  249G  70% /home/username/Public
//server/users/username
                      805G  556G  249G  70% /home/username/Documents
/dev/sdb1             1.9G  706M  1.1G  40% /media/LIVE

How do I know my device is /dev/sdb? Because a moment earlier — before I put in the USB disk — /dev/sdb wasn't on this list when I used df.

5 Now double check, using fdisk that you've got the right device. You're about to overwrite the device and you don't want to kill your hard drive by accident!

[root@cobh Downloads]# fdisk /dev/sdb

Command (m for help): p

Disk /dev/sdb: 2002 MB, 2002747392 bytes
32 heads, 63 sectors/track, 1940 cylinders, total 3911616 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x21260744

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1              63     3911039     1955488+   6  FAT16

Command (m for help): q

I know this is the right device because the size matches what's printed on the USB stick (2G =~ 2002MB) — and nothing else does. Now that I've double-checked, I can continue.

6 unmount any partitions on the device which are mounted.

[root@cobh Downloads]# umount /dev/sdb1 

7 Now issue the command:

[root@cobh Downloads]# livecd-iso-to-disk --format --reset-mbr Fedora-17-x86_64-Live-Desktop.iso /dev/sdb

Which causes this to happen:

Verifying image...
/home/fachtna/Downloads/Fedora-17-x86_64-Live-Desktop.iso:   8f867005fc8d23b3a9f0d3918d7ad825
Fragment sums: 937bd8e8d79fa61fdebca46ed56bb7f295116544a578b8c2c6c35f51cb9e
Fragment count: 20
Press [Esc] to abort check.
Checking: 100.0%

The media check is complete, the result is: PASS.

It is OK to use this media.
WARNING: THIS WILL DESTROY ANY DATA ON /dev/sdb!!!
Press Enter to continue or ctrl-c to abort

After taking a moment to check that I have the right device (in my example /dev/sdb - yours might be different) I press Enter as requested, then sit back and watch while all this goes on:

wipefs: WARNING: /dev/sdb: appears to contain 'dos' partition table
Waiting for devices to settle...
mke2fs 1.41.14 (22-Dec-2010)
Filesystem label=LIVE
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
122160 inodes, 488192 blocks
24409 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=503316480
15 block groups
32768 blocks per group, 32768 fragments per group
8144 inodes per group
Superblock backups stored on blocks: 
	32768, 98304, 163840, 229376, 294912

Writing inode tables: done                            
Creating journal (8192 blocks): done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 21 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.
Copying live image to target device.
squashfs.img
   655540224 100%   11.90MB/s    0:00:52 (xfer#1, to-check=0/1)

sent 655620321 bytes  received 31 bytes  12254586.02 bytes/sec
total size is 655540224  speedup is 1.00
osmin.img
        8192 100%    0.00kB/s    0:00:00 (xfer#1, to-check=0/1)

sent 8265 bytes  received 31 bytes  16592.00 bytes/sec
total size is 8192  speedup is 0.99
Updating boot config file
Installing boot loader
/media/tgttmp.AxZocV/syslinux is device /dev/sdb1
Target device is now set up with a Live image!
[root@cobh Downloads]# 

8 Now that I have a bootable USB device, I can reboot another computer, change the BIOS to boot from USB and run the live DVD without needing to modify the hard drive.


Last updated: 20150326-09:41