Due to a recent unknown mishap my macbook decided to go blank on it's LCD. So now, for portability I pulled out my linux "play"-station. Which I use for various experiments with linux. Best part about it, is that it's formatted every 2 days so, I've never really used USB disks to install, it's mostly done in the following manner.
The expectation is to at least have one system or at least grub on the system. If by any chance you have nothing and are on Windows, I don't really have a solution for you right now.
initrd, we'll need these later.
At this point, you can do 1 of 2 things.
dd the image onto an empty partition and then boot into it using grub's CLI
I normally prefer the 2nd one since it's faster and I normally make sure there's enough space to create a partition that can hold a linux install image (~4GB or more)
Now, you create a partition using your favorite tool and
dd the image onto
$ dd if=/image.iso of=/dev/sdXN
X with the disk number and
N with the partition.
Now you have a drive that can act as an installation drive.
At this point, there's 2 things we need to do.
Let's get started.
c (generally the shortcode to open
the grub CLI).
ls on the CLI to see the available disks
ls (hd0,gpt1) replace
hd0,gpt1 with whatever was listed by grub.
Set the root partition
grub> set root=(hd0,gpt1)
grub> linux /casper/vmlinuz toram quiet
/casper/vmlinuz with the path to
vmlinuz for the distro you are
casper/vmlinuz is the general path for ubuntu based images.
Next up, we add in
grub> initrd /casper/initrd
Now, the same applies here, you replace the path
/casper/ with the one for
your distro that you took note of in the starting.
At this point, all that's left is to boot into this drive.
If it all works well, and the kernel supports it, you should now have a linux system running off your RAM and you can start the installation as a normal one , or keep it this way as a recovery partition.
If you wish for it to be a recovery partition, it'll be easier to add this in as an entry to your grub config.
Hopefully this helps someone out, who'd like to fresh install and has no CD/DVD or USB thumbdrive handy and needs to do a fresh install or just jump to a new distro.