Starting Out

You can access a UNIX system in one of two general ways: either locally (that is, while sitting at the computer you are connected to), or remotely (by connecting to the computer over a network). Most of what you will learn in this book applies equally well to either case. In particular, the basic UNIX commands will work in exactly the same way Before you can start using those commands, however, you will need to know how to access your UNIX system.

Connecting Locally

To connect to a UNIX machine locally, you need to be physically at the computer. If that computer is a UNIX workstation, all you need to do is log in with your username and password. If you are using Mac OS X, you just need to run the Terminal application, available under Applications | Utilities, in order to access the UNIX command line that is built in to the operating system.

You can also run a version of UNIX, such as Linux, FreeBSD, or Solaris, on a PC. The next section describes where you can find one of these UNIX variants and how to get it running on your computer. Once it is installed, you just need to log in to the system, as on a UNIX workstation.

Installing a UNIX Variant on a PC

The process of installing a UNIX variant on a PC has become surprisingly straightforward. You will need a Pentium PC (or equally powerful machine), and you will probably want a CD-ROM drive so that you can install from a CD. Ideally, you will have a hard disk with at least 1 gigabyte free, but it is possible to run some versions of Linux (such as Knoppix) directly from the CD-ROM without installing to a hard drive at all.

You will also need to choose which UNIX variant to install. Chapter 1 discusses the different versions of UNIX that can be run on a PC. These include variants of Linux and BSD, as well as Solaris. Most of these variants can be purchased on a CD or downloaded for free. The downloads are typically in the form of an .iso file. This is a disk image that can be burned to a CD if you have a CD burner. Many of the UNIX variants listed in the next sections have guides on their web sites explaining exactly how to create an installation CD.

Once you have a CD with your UNIX variant on it, you can install by booting directly from the CD. If your computer does not boot from a CD, you have a few options. You may be able to get it to boot from a CD by changing a BIOS setting. If you are not comfortable modifying your BIOS, you can create a floppy boot disk that will allow you to install from a CD. Many of the UNIX variants have a “Getting Started” or “How to Install” section in their online documentation that explains how to do this. You could also try to find a variant that can be installed from floppy disks (such as FreeBSD, which has instructions on its web site for setting up the disks).

Once the installation program is running, you will be able to follow the directions on screen to complete the installation. The installation process will include setting up your hard drive and selecting which components of the operating system to install. You will also set up an account for system administration (often called the root account), and choose a separate login name and password for everyday use. For most of the variants listed in this chapter, this process is fairly straightforward. Even if you do not know much about installing an operating system, the installation program will suggest default settings that should work well for most users. In addition, the web sites for the UNIX variants include installation guides to step you through this process.

You can see examples of the installation process for many UNIX variants, including the versions of Linux discussed here, FreeBSD, and Solaris, at http://shots.osdir.com/. This web site, which also includes screenshots after installation is complete, can help you compare the feel of different versions before you choose which one to install.

Linux Distributions   If you decide to install Linux, you should know that there is no single “official” version of Linux. Instead, there are many distributions of Linux, each produced by a different organization. In general, these distributions have more similarities than differences. The differences between distributions have to do with the target audience (beginner or advanced users), the installation process (simple or complex), the applications that are included by default (for example, which desktop environments the distribution comes with), and the package management systems (how new applications are installed). In addition, some distributions are known for being particularly up-to-date, or especially stable, or very well supported.

A good starting point for choosing a Linux distribution is http://distrowatch.com/. This web site tracks the different distributions of Linux that are currently available. For each distribution, it includes information on where to get an installation CD, or how to download the distribution so that you can create your own CD. It also has a “Major Distributions” page listing the distributions that are currently most popular, with comments indicating which are best suited for a beginning user.

At the time of this writing, these are some of the most common and highly recommended Linux distributions, according to DistroWatch:

• Ubuntu (http://www.ubuntu.com/) is a relatively new Linux distribution, but it has become one of the most popular. Ubuntu is known for including up-to-date software and for being accessible even to new users. The variant Kubuntu includes the KDE desktop environment instead of GNOME (see Chapters 6 and 7 for information about desktop environments). Canonical, the sponsor of Ubuntu, has a policy of shipping free installation CDs on request. In addition to the installation CD, Ubuntu can be downloaded as a “Live CD” that allows you to run Ubuntu without installing it to the hard drive.

• Xandros Desktop (http://www.xandros.com/) is highly recommended for Windows users who want to start using Linux. It is considered one of the most easy-to-use distributions for beginners. Besides the Open Circulation Edition, which can be downloaded for free, Xandros sells boxed versions of its operating system, including the Deluxe Edition, which can run Microsoft Office and certain other Windows applications.

• Fedora Core (http://fedoraproject.org/) is sponsored by Red Hat, which is one of the most famous Linux brand names. It is one of the most widely used Linux variants, and is considered especially reliable.

• SUSE Linux (http://www.opensuse.org/) is another very popular distribution.

• Mandriva Linux (http://www.mandrivalinux.com/) is also popular and easy to use.

• Debian GNU/Linux (http://www.debian.org/) is popular among advanced users, but it may be more challenging to install than the other distributions on this list. Many other Linux distributions are actually based on Debian, including Ubuntu, MEPIS, and Knoppix.

• MEPIS Linux (http://www.mepis.org/) is a beginner-friendly distribution that can be run from a CD as well as installed on a hard drive. This allows new users to test the operating system before installing it, and to use the CD as a recovery disk if something goes wrong.

BSD Variants   The BSD variants include FreeBSD, OpenBSD, and NetBSD. Of these, FreeBSD is the most popular. It can be downloaded from http://www.freebsd.org/. FreeBSD has a reputation for being a remarkably stable operating system, and is very popular for servers. It is highly compatible with Linux applications. Installing FreeBSD may be more challenging for a beginner than installing some of the Linux distributions listed above.

Solaris   The Solaris 10 operating system, by Sun Microsystems, is now available as a free download. To download Solaris, go to http://www.sun.com/software/solaris/get.jsp. To buy Solaris 10 on CD for approximately $30, go to http://store.sun.com/ and click Operating Systems. Solaris is now largely open source and is mostly compatible with applications written for Linux.

Connecting Remotely

When you connect to a UNIX system remotely, you are using your computer to access another system that is running UNIX. Typically, this system supports many users at once. For example, many large universities offer a UNIX account to all their students. The students log in to the system from their own computers, either through the Internet or over the university network.

In order to connect to a UNIX system like this, you will need Internet access from your own computer. (In some cases, you may be able to dial in directly to the UNIX system, but the details for how to do this depend on the specific system configuration.) You will also need a terminal emulator application. This is a program that allows you to interact with the UNIX system. Finally, you will need to know the hostname of the system you are going to connect to (for example, amber.university.edu), and your login name and password. You can get this information from the administrator of the UNIX system.

Accessing a UNIX System from a PC

Microsoft Windows comes with a terminal application called HyperTerminal. HyperTerminal allows you to use telnet to connect to a remote system. However, HyperTerminal does not support ssh, a secure method of connecting that prevents hackers from stealing your passwords or data when they are sent over the network. Many UNIX systems are configured to allow only ssh connections.

Two of the most commonly used terminal emulators for Windows are PuTTY and SecureCRT. Both of these support ssh, in addition to telnet. PuTTY is freely downloadable from http://www.chiark.greenend.org.uk/~sgtatham/putty/. SecureCRT has more features but is a commercial product. To download a trial version or buy the full version, go to http://www.vandyke.com/products/securecrt/.

When you first run your terminal application, you will need to create a new connection. Your application should explain how to do this. For example, when you run PuTTY, it automatically opens a dialog box so that you can enter your connection information. You will enter the hostname of the UNIX system, and your login name and password. Once you are connected, you will be able to enter and run commands, just as you would if you were physically at the remote computer.

Accessing a UNIX System from Mac OS X

The Terminal application in Mac OS X allows you to connect to a remote system. Just type ssh followed by the hostname of your system, as in

 ssh amber.university.edu

You will be prompted to enter your login name and password. Once you are connected, you can enter commands as though you were sitting at the remote machine.