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mgallatin 03-23-2011 10:40 AM

If I dd copy a bootable usb drive to an iso will the iso be bootable?
So, heres my question...

If I dd copy a bootable usb drive to an iso will the iso be bootable?

I haven't tried it yet, but i'm going to. Heres the situation and tell me if I'm crazy.

I have several bootable CDs I use at work to do different things, so I went ahead and made a multi-boot usb stick with the isos on them and everything is golden. When i need something else, I am able to slap the ISO on the usb stick, edit the menu.lst and I'm good to go.

The problem is, for some of our equipment I have a bootable USB stick that I have to use. I tried copying the files on the bootable USB to my multi-boot usb and setup grub to boot it (which admittedly I'm no expert at), but have had no luck.

So now I'm thinking, I'll use dd to copy the bootable USB stick to an iso (using bs=2048) and then do my normal setup with an ISO and maybe it will work.

Please let me know if I'm crazy, I'm gonna try it this afternoon I think, so I will let you know what I find. Or, if anyone has tried this, are there any pitfalls I should know about?

Thanks for your insight.

szboardstretcher 03-23-2011 10:57 AM

My question is: Do you have a HOWTO available for what you did? That sounds like a great idea. Being able to have one bootable drive with Fedora, Ubuntu, Centos, RHEL, Suse, Kubuntu, et al would be wicked.

What is your process?

mgallatin 03-23-2011 11:07 AM

I used this guide... didn't use all of it, mostly the stuff about making the USB bootable, and putting the Ultimate Boot ISO on it (although I dont use that ISO, the same process seems to work for other bootable ISOs) Yeah, I think its either OSX or Windows Slanted, but I use windows for my desktop at work.

icecoder 03-23-2011 11:13 AM

if you dd a disk to an image, and the disk is bootable, then the image will be bootable (obviously, if you dd a cdrom do not try to burn the image onto a hard drive..)

EDIT: same thing with USB sticks, the image is bootable if the stick is bootable, maybe your grub commands are wrong.

mgallatin 03-23-2011 04:42 PM

Okay so, just making a bootable ISO didn't exactly work in my case, but I did finally get it to work. Also I found that the instructions at work great for some ISOs, not so great for others. For my bootable USB image to work on my multi-boot usb, I had to have both a plain copy of the bootable USB files, and the whole ISO. I also used the memdisk file from syslinux and my grub entry looked like this:


title BootableUSB
kernel /memdisk
initrd /BootableUSB.iso

Yeah, it seems very hacky to have 2 copies of the bootable USB stick on the multi-boot USB stick, but its a funny USB stick to begin with so it doesn't surprise me. Its like it uses the image to boot, then reads the regular files off the USB stick. It does take a long time to load (i think its the time it takes to copy the 500MB iso to memory). This may not help anybody, but I thought I'd tell ya'll how I finally got it to work, cause I hate it when someone replies with "I got it working" and no details.

I tried to boot an Xubuntu Live CD iso the same way other isos are booted in the instructions, but it didn't work (i got into a busybox shell). If you're interested in putting a "liveCD" version of Ubuntu (or Xubuntu or Kubuntu or etc...) on a USB stick, I found the section titled "Create Bootable USB Manually" at this link: had all the info I needed to create a bootable Xubuntu part of my multiboot stick. (Amazingly fast boot times btw, I was shocked how quick it loaded the first time).

Anyways, I'm gonna mark this thread as solved, if anyone has any more insight into a better way of doing this, let me know.

EDDY1 03-23-2011 05:46 PM

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