So here's my dilemma. I tried to install Debian and it wiped out Windows entirely after I installed the GRUB Bootloader. Thinking, "ok, I'll just get it back after I finish installing Debian," I completed the installation and the final product turned out to be just a command line. I'm currently trying to install Gnome for the GUI, but in case that doesn't work for whatever reason, is there a way to uninstall the entire Debian OS from its own command line, and from here would I still be able to install Ubuntu? The only reason I'm concerned about deleting Debian is because when I popped in a Windows or Ubuntu ISO to the BIOS boot menu, it came up with an error containing the phrase, "syslinux" so clearly it knows that Linux is already installed. I believe it also said "cannot find kernel image." Is there any workaround for this? Thanks in advance.
Answers
If you're just looking to wipe the entire hard drive, you can just run:
sudo dd if=/dev/zero of=/dev/sda bs=4M
Assuming that sda is is the hard drive you want to wipe.
That being said, be careful! This will wipe THE ENTIRE HARD DRIVE, INCLUDING ANY OTHER OPERATING SYSTEMS YOU MAY HAVE INSTALLED. Since you overwrote your windows with debian anyway, you're probably hosed on that front, so this isn't so bad in your case.
I'm also not sure how long it will take - it took <1s on a 4 GB flash drive for me, but for a large HDD it could take a while.
That being said, this is not the best way to go about this. What you really want to do is
just pop in the live CD/USB and try again. The way to do this, from your current situation is:
For ubuntu 14.04 64-bit:
wget http://releases.ubuntu.com/14.04.1/ubuntu-14.04.1-desktop-amd64.iso
Plug in a flash drive, type dmesg and see at what /dev/sdX it mounted it (I'll say /dev/sdc for the example)
sudo dd if=ubuntu-14.04.1-desktop-amd64.iso of=/dev/sdc
The magic thing about ubuntu ISOs is that you can write them directly to the metal of a flash drive and be able to boot into it.
Reboot your computer and choose the flash drive from the boot menu your BIOS gives you, continue installing ubuntu as normal.
