There are may reason why someone may not want to or be able to use a USB stick, CD, or DVD to install a Linux distribution (no CDs laying around, and your mobo won’t boot to USB, or your just don’t feel like it, cool.)  Luckily, you can easily install Linux without needing either.  I will, naturally, be using Fedora as an example, and giving a guide for both users currently running Linux or Windows.

How it works:

If you don’t care, skip this section.  Basically, what linux installers do is boot a kernel and ram disk (initrd) that loads an installer.  In Fedora’s case, this is anaconda.  When only the kernel and ram disk are present, the installer will then prompt the user for where to look for the installer, which can be an .iso on the hard drive, USB stick, or an ftp or http mirror somewhere on the web.  In this guide, we will use the latter method.  From there, the installer should function just as normal, as if you had made and booted the installer by a more conventional method.

Preparation (for both Linux and Windows users):

First, you need to download the kernel (vmlinuz) and ram disk (initrd.img) from any Fedora repository (Please note, this method works for other distros but the kernel and initrd may be named differently.)

Download the kernel (vmlinuz) and ram disk (initrd.img) from any one of these places:
List of 32-bit repositories.
List of 64-bit repositories.

Doing the work (Linux users):

1. As root, place the vmlinuz and initrd.img in /boot using mv or cp.
2. Edit /etc/grub.conf to add a boot entry (nano /etc/grub.conf or vi /etc/grub.conf)
Here’s an example assuming your /boot partition is the first on your primary drive:

Title Fedora 15 installer
root (hd0,0)
kernel vmlinuz

Special Considerations: Most other linux distros use /boot/grub/menu.lst instead of grub.conf, however the format will be the sameSecondly, if /boot is not a separate partition, you must give the root of your / partition and give a /boot prefix on the kernel and initrd lines, example:  kernel /boot/vmlinuz).

When you reboot, you should be able to boot into the installer.

Windows (and Linux alternative method):

For Windows we will use unetbootin (the same steps will also work for Linux).
1.  Download unetbootin from here (Pick “Save” when prompted).
(Linux users may skip steps 2 and 3, and simply run: unetbootin showcustom=yes)
2.  Unfortunately, the kernel and ram disk options are now hidden by default in Unetbootin, so you will need to create a shortcut to the Unetbootin.exe file you downloaded (Right click, Make Shortcut here).  
3.  Right click on the shortcut and after the location pointing to unetbootin.exe add showcustom=yes, and save the shortcut.
4.  Now launch the shortcut.

5.  With custom selected, just point kernel: to where you saved the vmlinuz file, and initrd: to where you save the initrd.rd.
6.  Make sure you then set it to install to C:\, then click OK and reboot.

Note that while Unetbootin has worked in the past for booting install DVDs and live CDs from hard drive, this no longer works with Fedora 14 or 15.  However, this above method should work regardless.

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