The write command
The write command displays a line in the login message dialog box. It has a simple syntax:
write “message” If you want to include an identifier in the output, use a percent sign before
the identifier: write LAST_NAME
You can string together several identifiers and text strings by separating them with semicolons:
write “Hello “;LAST_NAME
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Chapter 21
Using a Linux Server
In This Chapter
䊳
Finding out about Linux and how it differs from Windows
䊳
Choosing which version of Linux to use for your server
䊳
Installing Linux
䊳
Configuring Linux network settings and user accounts
䊳
Using Samba to create a file server
L
inux, the free operating system based on Unix, is becoming more and more popular as an alternative to expensive server operating systems
such as Windows Server 2003 and NetWare. In fact, by some estimates, there are more computers now running the Linux operating system than there are
running the Macintosh operating system. You can use Linux as a Web server for the Internet or for an intranet, and you can use it as a firewall or a file and
print server on your local-area network.
Linux was started in 1991 by a Linus Torvalds, who was at the time an under- graduate student at the University of Helsinki in Finland. Linus thought it would
be fun to create his own operating system for his brand-new PC, based on Unix. In the nearly ten years since Linux was first conceived, Linux has become a
full-featured operating system that is fast and reliable.
In this chapter, you find out the basics of setting up a Linux server on your network and using it as a file server, as a Web server for the Internet or an
intranet, as an e-mail server, and as a router and firewall to help connect your network to the Internet.
Linux is a complicated operating system. Learning how to use it can be a daunting task, especially if your only prior computer experience is with
Windows. Fortunately, Wiley Publishing, Inc. has a plethora of For Dummies books that make learning Linux less painful. Check out Linux For Dummies,
2nd Edition by Jon “maddog” Hall, Linux For Dummies Quick Reference, 2nd Edition by Phil Hughes, and Linux Administration For Dummies by Michael
Bellomo.
Comparing Linux with Windows
If your only computer experience is with Windows, you are in for a steep learning curve when you first get into Linux. There are many fundamental
differences between the Linux operating system and Windows. Here are some of the more important differences:
⻬ Linux is a multiuser operating system. That means more than one user
can log on and use a Linux computer at the same time. Two or more users can log on to a Linux computer from the same keyboard and monitor
by using virtual consoles, which let you switch from one user session to another with a special key combination. Or, users can log on to the
Linux computer from a terminal window running on another computer on the network.
In contrast, most versions of Windows are single-user systems. Only one user at a time can log on to a Windows computer and run commands.
Windows 2000 and 2003 can be configured as a multiuser system with terminal services.
⻬ Linux does not have a built-in graphical user interface GUI as Windows does. Instead, the GUI in Linux is provided by an optional
component called X Window System. You can run Linux without X Window, in which case you interact with Linux by typing commands.
If you prefer to use a GUI, you must install and run X Window.
X Window is split into two parts: a server component, called an X server, which handles the basic chores of managing multiple windows and pro-
viding graphics services for application programs, and a user interface component, called a window manager, which provides user interface fea-
tures such as menus, buttons, toolbars, a taskbar, and so on. Several dif- ferent window managers are available, each with a different look and
feel. With Windows, you’re stuck with the user interface that Microsoft designed. With Linux, you can use the user interface of your choosing.
⻬ Linux cannot run Windows programs. That means you cannot run
Microsoft Office on a Linux system; instead, you must find a similar program that is written specifically for Linux. Many Linux distributions
come with an office suite called StarOffice, which provides word pro- cessing, spreadsheet, presentation, graphics, database, e-mail, calendar,
and scheduling software. And the documents created by StarOffice are compatible with Microsoft Office. Thousands of other programs are
available for Linux. There are Windows emulator programs — the best- known is Wine — that can run some Windows programs on Linux. But
the emulators can run only some Windows programs, and it runs them slower than they would run on a Windows system.
⻬ Linux doesn’t do Plug and Play the way Windows does. Although
the major Linux distributions come with configuration programs that can automatically detect and configure the most common hardware
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components, Linux does not have built-in support for Plug-and-Play hardware devices. As a result, you’re more likely to run into a hardware-
configuration problem with Linux than with Windows.
⻬ Linux uses a different system for accessing disk drives and files than Windows does. For an explanation of how the Linux file system works,
see the “I can’t see my C drive” sidebar that’s coming up in this chapter.
⻬ Linux runs better on older hardware than the current incarnations of Windows do. Linux is an ideal operating system for an older Pentium
computer with at least 32MB of RAM and 2GB of hard-drive space. If you’re fond of antiques, however, you can with a bit of juggling get
Linux to run well on even a 486 computer with as little as 4MB of RAM and a few hundred MB of disk space.
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I can’t see my C drive
Well, no, but that’s normal. Linux and Windows have completely different ways of referring to
your computer’s disk drives and partitions. The differences can take some getting used to for
experienced Windows users.
Windows uses a separate letter for each drive and partition on you system. For example, if you
have a single drive formatted into three parti- tions, Windows identifies the partitions as
drives C, D, and E. Each of these drives has its own root directory, which can in turn contain
additional directories used to organize your files. As far as Windows is concerned, drives C,
D, and E are completely separate drives, even though the drives are actually just partitions on
a single drive.
Linux does not use drive letters. Instead, Linux combines all the drives and partitions into a
single directory hierarchy. In Linux, one of the partitions is designated as the root partition.
The root is roughly analogous to the C drive on a Windows system. Then, the other partitions
can be mounted on the root partition and treated as if they were directories on the root
partition. For example, you might designate the first partition as the root partition and then
mount the second partition as user and the third partition as var. Then any files stored
in the user directory would actually be stored in the second partition, and files stored in the
var directory would be stored on the third partition.
The directory which a drive mounts to is called the drive’s mount point.
Notice that Linux uses regular forward slash characters to separate directory names
rather than the backward slash characters \ used by Windows. Typing backslashes instead
of regular slashes is one of the most common mistakes made by new Linux users.
While we’re on the subject, Linux uses a differ- ent convention for naming files, too. In Windows,
file names end in a three-letter extension that is separated from the rest of the file name by a
period. The extension is used to indicate the file type. For example, files that end in .exe are
program files, but files that end in .doc are word-processing documents.
Linux doesn’t use file-name extensions, but periods are often used in Linux file names to
separate different parts of the name — and the last part often indicates the file type. For exam-
ple, ldap.conf, and pine.conf are both configuration files.
