Here is a list of some Linux distributions that can be run from a USB Flash drive, and the approximate size drive you will need for each of them.
Ubuntu / Kubuntu / Xubuntu - 2 GB or larger
gOS - 1 GB or larger
Damn Small Linux - 64 MB or larger
Puppy Linux - 128 MB or larger
Pendrivelinux - 1 GB or larger
Knoppix - 1 GB or larger
Dreamlinux - 1 GB or larger (2 GB or larger for Persistent).
Yes. Many Linux distributions can be easily booted from a USB Flash drive. With some modification, booting Windows XP is also possible.
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The following are designed primarily or entirely to function as LiveCD distributions: * Knoppix * Damn Small Linux * Feather Linux * Slax * Archie The following have a LiveCD component, but were designed more for installation to a hard drive: * Ubuntu (and derivatives like Kubuntu and Xubuntu) * Freespire * PCLinuxOS * Fedora * Mandriva * Pardus
Nothing. Most Linux distributions are free of charge. There are some distributions that are commercially sold, though those sales are more likely subscriptions for support, not for the Linux distribution itself.
Some will, if you install Mono. By default, most Linux distributions do not include support for them, though.
SSH1 can technically be used on virtually all distributions, yes. It is not, however, in wide use due to certain security vulnerabilities.
There's Ubuntu, Debian, Red Had, Fedora, Gentoo, Arch, Mint, SuSE, Slackware... A good way to find out is to look into Distro Watch. The web site more or less keeps a monitor on how popular a given Linux distribution is.
There are many open-source OS distributions (distros) branching out from the Linux Kernel. Ubuntu, Linux Mint, Puppy, to name but three.
Lots of Linux distributions, and other free operating systems, will fit on a 1 GB hard drive. The real question is what you are trying to accomplish with said operating system. For a small desktop system, look at: Puppy Linux Damn Small Linux Feather Linux QNX (free for personal use, partially open-source) KolibriOS AROS Syllable For a server, almost any server edition of Linux will work, such as: Ubuntu Server Fedora Debian (do a netinstall, and install only the parts you need) With some tweaking, you could probably also fit a standard Debian, Slackware, or Gentoo. Although I wouldn't recommend it, you could use the same method for putting Ubuntu on a 1 GB flash drive for a hard drive as well.
Some Linux distributions have the ability to be installed over a network. However, it should be noted that this is an endeavor that is intermediate to expert in difficulty.
Yes. There are several Linux distributions that can be freely downloaded. To install them, you would probably need to burn it to a CD or DVD, but some of them can install from a portable hard drive.
Installing Linux on a USB Flash drive does not require the conversion of files. The most difficult part is setting up the bootloader. Simply downloading a copying files to the disk will not install a bootloader.