Basics of Virtual Box & Linux

VirtualBox

VirtualBox is a cross-platform virtualization application. What does that mean? For one thing, it installs on your existing Intel or AMD-based computers, whether they are running Windows, Mac, Linux or Solaris operating systems. Secondly, it extends the capabilities of your existing computer so that it can run multiple operating systems (inside multiple virtual machines) at the same time. So, for example, you can run Windows and Linux on your Mac, run Windows Server 2008 on your Linux server, run Linux on your Windows PC, and so on, all alongside your existing applications. You can install and run as many virtual machines as you like -- the only practical limits are disk space and memory.

VirtualBox is deceptively simple yet also very powerful. It can run everywhere from small embedded systems or desktop class machines all the way up to datacenter deployments and even Cloud environments.

Install Virtual Box

Download VirtualBox. VirtualBox from Oracle is available for free from the developer's website. Make sure that you download the correct version for your operating system.

There are multiple choices for Linux versions. Choose the package that matches your Linux distribution, or use the "All distributions" option if your Linux distribution is not listed

Install the VirtualBox program. If you are using Windows, double-click the setup file and follow the prompts to install. If you are using a Mac, open the DMG file that you downloaded and drag the VirtualBox file to your Applications folder.

During the Windows installation, keep all of the options set to their default.

Start the program. VirtualBox allows you to manage your various virtual machines, and easily create new ones. You can run VirtualBox directly from the installation program, or you can start it from the desktop icon.

Because that's what it was developed on and there are many places in the code (at least, until recently) that assumed it was running on Linux (specifically, RHEL/CentOS).    Furthermore, that's what all of the leading vendor distributions support.

Bottom line is that from a production standpoint, it mind-bogglingly stupid to try and use an unsupported operating system for any critical piece of infrastructure.  Managing a Hadoop cluster gives you enough headaches without intentionally inflicting additional pain upon yourself.   Running a different OS has a huge amount of risk for virtually zero reward.

Why Linux?

One of the most confusing things for the newcomer to Linux is how many distributions, or versions, of the operating system there are. Ubuntu is the one most people have heard of, but there are hundreds of others as well, each offering some variant on the basic Linux theme.

Choosing the distribution--or "distro"--that's right for your business will depend in large part on five key factors, as I've already described. It's also helpful, however, to have a basic understanding of how the major Linux distros differ.

Different flavors of Linux

What follows, then, is a roundup of sorts of the top 10 Linux distributions today.

1. Ubuntu

Yes, Ubuntu has become the poster child for Linux these days, and no wonder--it's the most popular distro by far, garnering more than 2,200 hits per day on the Distrowatch site alone, compared with some 1,400 for Fedora, the No. 2 contender.

Ubuntu is actually a relatively late arrival on the Linux scene, having been announced in just 2004, but it's more than made up for that shorter history. Founded by South African millionaire Mark Shuttleworth, Canonical--the company behind Ubuntu--for many years shipped Ubuntu CDs to interested users for free, thus speeding its market penetration.

Ubuntu is based on Debian (see below) and includes well-known apps such as Firefox and OpenOffice.org. It has a predictable, six-month release schedule, with occasional Long Term Support (LTS) versions that are supported with security updates for three to five years.

Ubuntu is also notable for its ease of use and its inclusion of a migration assistant for Windows users and support for the latest technologies. Version 10.10 of Ubuntu--also known as Maverick Meerkat--will include a multitouch and gesture stack. The final iteration of that version is due out next month.

It's also worth understanding that Ubuntu is available in various remixes and spin-off sub-distros targeted at specific niches, such as Kubuntu, Xubuntu and Lubuntu. Most of these differ primarily by offering a desktop environment other than Ubuntu's standard GNOME.

2. Fedora

Fedora is the free version of Red Hat, whose RHEL (Red Hat Enterprise Linux) has been a commercial product since 2003. Because of that close connection, Fedora is particularly strong on enterprise features, and it often offers them before RHEL does.

Fedora also offers a six-month release schedule, and its security features are excellent. While some have viewed it as a cutting-edge distro for the Linux "hobbyist," I think improvements over the years and widespread popularity have combined to make it a good choice for newer Linux users as well.

3. Linux Mint

Currently in Distrowatch's third spot in popularity, Linux Mint is an Ubuntu-based distro that was just launched in 2006. The operating system adds to Ubuntu with its own, distinct desktop theme and a different set of applications; also unique to the distro are a variety of graphical tools for enhanced usability, such as mintDesktop for configuring the desktop environment, mintInstall for easier software installation and mintMenu for easier navigation.

Mint enjoys a well-deserved reputation for ease of use, so it's another good one for beginning users. It also includes some proprietary multimedia codecs that are often absent from larger distributions, thereby enhancing its hardware compatibility. Mint doesn't have a fixed release schedule, but typically a new version comes out shortly after each stable Ubuntu release.

4. openSUSE

With some 1,200 hits per day on Distrowatch, openSUSE holds the No. 4 spot in popularity on the site and is also the foundation for Novell's SUSE Linux Enterprise Desktop and SUSE Linux Enterprise Server products.

The package's administration utility, YaST, is widely acknowledged as one of the best, and its boxed edition comes with some of the best printed documentation you'll find for any distro. I'd say openSUSE rates a "medium" on difficulty level.

5. PCLinuxOS

Rather than GNOME, PCLinuxOS uses the KDE desktop environment and is essentially a lighter-weight version of Mandriva (see below). With good support for graphics drivers, browser plugins and media codecs, PCLinuxOS can be a good choice for beginners. Its release cycle can be erratic, though, and there is also no 64-bit version of the software.

6. Debian

Dating back to 1993, Debian is currently known as one of the most well-tested and bug-free distros available today. Though it serves as the foundation for Ubuntu, most view Debian as a distro best-suited for those experienced with Linux. The distro uses all open-source components, which is a good thing, but means it can be more difficult to achieve compatibility with proprietary code such as wireless network drivers. Debian also has a relatively slow release cycle, with stable ones coming out every one to three years.

7. Mandriva

Formerly known as Mandrake, Mandriva is notable for its cutting-edge software, excellent administration suite and 64-bit edition. It was also the first major distribution to jump on the netbook bandwagon with out-of-the box support. Nevertheless, Mandriva has been struggling lately as a result of some controversial decisions made by its French maker. It recently restructured, with the result that some view the future of its community version as uncertain.

8. Sabayon/Gentoo

Italian Sabayon is essentially a LiveCD version of Gentoo, which is known for allowing users to individually optimize each component. Both are considered advanced Linux distributions aimed primarily at experienced users.

9. Arch Linux... plus Slackware

Arch is another package aimed primarily at experienced users interested in tweaking and optimizing their systems. Though not in the top 10 currently, Slackware is similarly oriented toward Linux gurus.

10. Puppy Linux... plus DSL

Last on Distrowatch's top 10 currently is Puppy Linux, a compact distro that's ideal for older hardware and situations where computing resources are minimal. (Damn Small Linux, incidentally, is similar.) Though it has a small footprint, Puppy is still full-featured and includes a variety of configuration and application installation wizards. The whole OS is small enough to run directly from system RAM, so applications start quickly and respond to user input instantly.

Unity Shell (Ubuntu UI)

Unity is a graphical shell for the GNOME desktop environment developed by Canonical Ltd. for its Ubuntu operating system. Unity debuted in the netbook edition of Ubuntu 10.10. It was initially designed to make more efficient use of space given the limited screen size of netbooks, including, for example, a vertical application switcher called the launcher, and a space-saving horizontal multipurpose top menu bar.

Unlike GNOME, KDE Software Compilation, Xfce, or LXDE, Unity is not a collection of applications but is designed to use existing programs.

Unity is part of the Ayatana project, an initiative with the stated intention of improving the user experience within Ubuntu. In addition to Unity, there are Application Indicators and other projects such as MeMenu, the notification system and the application NotifyOSD gathered.

The Unity user interface consists of several components:

·         Top menu bar – a multipurpose top bar, saving space, and containing: (1) the menubar of the currently active application, (2) the capture bar of the main window of the currently active application including the maximize, minimize and exit buttons, (3) the session menu including the global system settings, logout, shut down and similar basic controls, and (4) the diverse global notification indicators including the time, weather, and the state of the underlying system.

·         Launcher – a dock that also serves as a window switcher. Multiple instances of an application are grouped under the same dock icon, with a number of indicators to the side of the icon showing how many instances are open. The user has a choice whether or not to lock an application to the launcher. If it is not locked, an application may be started using the Dash or via a separately installed menu.

·         Quicklist – the accessible menu of launcher items.

·         Dash – an overlay that allows the user to search quickly for information both locally (installed applications, recent files, bookmarks, etc.) and remotely (Twitter, Google Docs, etc.) and displays previews of results. The Dash search feature was the subject of the privacy controversy.

·         Head-up display (HUD) – introduced with Ubuntu 12.04. It allows hotkey searching for top menu bar items from the keyboard, without the need for using the mouse, by pressing and releasing the Alt key.

·         Indicators – a notification area (similar to an OS X menu extra), containing displays for the clock, network and battery status, sound volume etc.

Basic Linux Commands (enough to get started with Hadoop)

Command	Description
cat [filename]	Display file’s contents to the standard output device (usually your monitor).
cd /directorypath	Change to directory.
chmod [options] mode filename	Change a file’s permissions.
chown [options] filename	Change who owns a file.
clear	Clear a command line screen/window for a fresh start.
cp [options] source destination	Copy files and directories.
date [options]	Display or set the system date and time.
df [options]	Display used and available disk space.
du [options]	Show how much space each file takes up.
file [options] filename	Determine what type of data is within a file.
find [pathname] [expression]	Search for files matching a provided pattern.
grep [options] pattern [filesname]	Search files or output for a particular pattern.
kill [options] pid	Stop a process. If the process refuses to stop, use kill -9 pid.
less [options] [filename]	View the contents of a file one page at a time.
ln [options] source [destination]	Create a shortcut.
locate filename	Search a copy of your filesystem for the specified filename.
lpr [options]	Send a print job.
ls [options]	List directory contents.
man [command]	Display the help information for the specified command.
mkdir [options] directory	Create a new directory.
mv [options] source destination	Rename or move file(s) or directories.
passwd [name [password]]	Change the password or allow (for the system administrator) to change any password.
ps [options]	Display a snapshot of the currently running processes.
pwd	Display the pathname for the current directory.
rm [options] directory	Remove (delete) file(s) and/or directories.
rmdir [options] directory	Delete empty directories.
ssh [options] user@machine	Remotely log in to another Linux machine, over the network. Leave an ssh session by typing exit.
su [options] [user [arguments]]	Switch to another user account.
tail [options] [filename]	Display the last n lines of a file (the default is 10).
tar [options] filename	Store and extract files from a tarfile (.tar) or tarball (.tar.gz or .tgz).
top	Displays the resources being used on your system. Press q to exit.
touch filename	Create an empty file with the specified name.
who [options]	Display who is logged on.