TechRepublic's Linux primer
(Originally published 4/29/01. Updated 12/09/04)
This primer is meant to serve as a comparative walk-through for many aspects of Linux. The comparative
aspect of this primer takes into consideration that most readers will have a basic familiarity and
understanding of Windows 2000 or Windows XP and a desire to learn something challenging, fulfilling,
and rewarding.
For every Windows action, there's a comparative Linux action, and with every action, there's an
operating system (OS) response. Throughout this document, I'll explore various commands and events
that both operating systems share and I’ll show how to invoke simple processes and parallel applications.
Because of the distinct individuality of the various Linux distributions (Red Hat Linux, Caldera Open Linux,
SuSE, Debian, and Mandrake), this primer will take the liberty of dealing with one particular distribution.
Red Hat Linux has risen above all other flavors of Linux to become the most popular and hottest-selling
Linux product to date. This is not to play favorites or to say that one distribution is better than the other.
Choosing one distribution as a focal point is merely a matter of convenience.
This primer is divided into individual sections: system layout, startup and shutdown, basic file
processes, using removable and irremovable drives, the desktop, program installation, system
configuration, network configuration, maintenance, basic help systems, and dual booting. Let's begin by
examining the system layout.
System layout
The Windows system layout is a fairly straightforward. The C: drive resides on the DOS partition and
contains all of the system and non-system folders and files. On the C: drive, you’ll typically find:
 A set of folders that houses applications (Program Files).
 Windows general files (Windows).
 Files and settings users have created or chosen (Documents and Settings).
 User and application files created in the file tree.
Within the Windows directory, you’ll find the various system folders and files necessary for the basic
functionality of Windows. Housed within this same directory (Windows) are the .ini, .bat, .com, and
various other files that make up the heart of the Windows operation. It is possible to make the system
unbootable, or unstable, by making changes to these files. This problem is somewhat negated in the
more recent versions of Windows by having an Administrator and regular users.
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The Windows file tree structure shown here doesn’t include all existing files and folders, but it should
look familiar (Figures A and B).
FIGURE A
FIGURE B
The top half of the Windows file tree structure
Prior to Windows NT, the Windows OS
was a single-user environment. Windows 9x
was configured with one user who uses,
administers, and maintains the
The lower half of the Windows file tree structure
system. In this configuration, it's
very possible for a user to
accidentally take the system into
an irreversible state. Linux doesn't allow this behavior. Like UNIX, Linux is based on a multiuser
environment in that there is an administrator (called root) who is the only user allowed to execute many
tasks. Root can do such things as:







Add users
Delete users
Create dial-up accounts
Configure networking
Install and uninstall programs
Make changes to global configurations
Access all user accounts
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Windows NT, Windows 2000, and Windows XP have added the concept of multiuser systems and the
administrator account, thus relieving many of the issues of prior versions.
The user, in Linux, is the everyday user. Users have a limited set of permissions that allow them to
execute certain tasks and control only limited environmental variables. It's very easy for a user to break
his or her account or desktop. However, if users break, or corrupt, their desktop in Linux, all other users,
including root, will still have the use of their own accounts. This design makes for a very safe and secure
environment.
The first postinstall task is to have root set up the various user accounts. If you're using the machine as
a single-user desktop, simply create a user that will be used for everyday computing. The new user is
created in one of two ways: through linuxconf or at the command line. The simplest method is through
linuxconf; which is where root can create the new user, give the new user permissions, and add groups to
the user. At a prompt (and as root), type linuxconf. Once the linuxconf application has started, scroll down
to User Accounts and choose Add. In the Username field, provide a name for your user. Feel free to be
creative.
The only other field in this tab that you’ll need to concern yourself with is the Full Name field. Provide
the requested information and move to the Privileges section. For safety’s sake, leave the new user’s
permissions set to the minimum level. Now activate these changes. Once this user is created, log out of
root and log in as the new user. The security of running under user instead of under root is well worth the
hassle of having to su to make system changes (more on su later).
At first, this will seem more of an annoyance than a feature. However, the ability to retain global
configurations and control all levels of setup, permissions, and customizations while being free to tinker
with user accounts will quickly win you over to the multiuser environment. With the multiuser environment,
a single controlling unit acts as a sort of overlord to the entire system. Yes, it sounds daunting, but the
tasks of setting up devices and altering critical file systems and processes should be left to those with the
knowledge of administering a system. If you don’t possess such knowledge, then you won't have to worry
about harming your desktop system—it’s as simple as that.
Linux uses the concept of directories, instead of folders. This comes from the character-based roots of
Linux. A directory is also a collection of related files and directories. Directories are represented in the
Linux GUI as a folder, making the distinction mostly semantic for average users. The administrative user
will need to understand the directory concept.
Now that you have a basic understanding of the multiuser structure, let's look at the Linux layout. As
mentioned previously, instead of folders, Linux uses directories, and each directory is stored in a mountpoint. This mount-point acts as a sort of logical location so that the OS can remember where each file is
placed. The main directory for the system is simply /. Yes, it's that simple; / is where it all begins. Housed
within / are the following directories: bin, dev, home, /usr/bin, /usr/sbin, var, /boot, and /etc, among others.
Here is a basic listing of what resides in each of these directories:



bin: This directory contains the most essential UNIX commands, such as ls, awk, cat, chmod,
chown, cp, dd, df, mount, mkdir, rm, rmdir, and touch. These essential commands are the
backbone of the Linux/UNIX command environment. The bin directory is, by default, located in
the $PATH so that all commands residing within bin are global. (They can be executed from any
directory.)
dev: This directory holds the files that communicate with the machine’s hardware. This directory
contains devices that connect your modem, your CD-ROM, your Ethernet, your floppy drive, and
your hard drive to your OS. Almost the entire configuration of these devices is handled during the
install.
home: Home is literally where the heart is! After you have added your user account, home will
contain a subdirectory with that user name. For example, if you added the user Chuck, /home will
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





contain the Chuck directory. The explicit path to Chuck's home directory is /home/Chuck. All of
the working directories and configurations are housed within the user’s home directory. Note that
a user has no access to the other users' home directories; therefore, each user's configuration is
local to only that user. This setup also aids in security. For example, you have a Bob and a Chuck
on your system. Bob will not be able to change directory (cd) into /home/chuck, nor will Chuck be
able to cd into /home/bob. Likewise, Bob won’t be able to read Chuck's files (as long as Chuck
has not set the permissions of his files to global—more on permissions later).
/usr/bin: This directory contains other commands, and the difference between /bin and /usr/bin is
arbitrary. The split between /bin and /usr/bin was merely a way to divide the vast number of
commands local to a UNIX-like system.
/usr/sbin: This directory houses commands that are used only by superuser (root). Such
commands include netcfg, sndconfig, linuxconf, and netconf. These commands are critical, and
improper use can bring a system to a screeching halt.
/var: This directory contains most administrative files, including the log files used by various
utilities. These log files are invaluable tools if your system develops a problem. All logins and
boots are recorded in this directory. One of the most useful of these files is /var/log/messages.
Most of these files are accessible only by root.
/boot: This directory contains the kernel and other files used during booting. It is crucial that only
the well-versed toy with these files.
/etc: This directory contains files used by subsystems, such as networking, network file systems
(NFS), and mail. This directory also contains tables of networking services and mountable disks.
/opt: This is the directory which contains many applications users will use, and install.
This is a simple—not complete—listing. Each distribution adds various directories and files to this basic
setup (Table A).
TABLE A
Windows
C:
Program files
System
Start menu
E: (CD-ROM)
Control Panel
Linux
/
/home/user
/usr/sbin and /boot
/usr/bin
/mnt/cdrom (when mounted)
Linuxconf
This is a simple side-by-side comparison of the Windows and Linux directories.
Again, this is a very minimal comparison, meant only to provide an overview of the comparative
structure between Windows and Linux.
In Linux, drives fall under a completely different naming system (Table B).
TABLE B
Windows
A: (first floppy drive)
B: (second floppy drive)
Entire first hard drive
C: (first HD partition)
D: (second HD partition)
E: (CD-ROM)
Linux
/dev/fd0
/dev/fd1
/dev/hda
/dev/hda1
/dev/hda2
/dev/cdrom
Linux drive names are quite different than their Windows counterparts.
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Startup/shutdown
Now that you have a basic understanding of the Linux file structure, let's examine how to start your
machine.
Startup
The Linux boot process differs from the very beginning. After the BIOS posts, a Linux native application
(named LILO) starts. LILO is a general-purpose boot manager that can boot nearly any type of OS.
Typically, LILO will reside on the master boot record (MBR) and will be the first piece of code executed
after the BIOS. At the LILO prompt, you can press [Tab] to display the various operating systems
available at boot. As previously stated, LILO can boot nearly any type of OS. However, in the case of dual
booting between Linux and Windows, the Windows OS must be installed first. (Otherwise, the Windows
boot loader will overwrite LILO, and Linux will be unbootable without the aid of a boot disk.)
If your machine is configured to dual boot between operating systems with LILO resting on the MBR,
simply press [Tab] at the LILO: prompt, and you'll get a listing of the commands to boot each OS.
Typically, the commands are as follows:
 To boot Linux, either press [Enter], or type linux and then press [Enter].
 To boot Windows, type dos and press [Enter].
On a properly installed Linux system, the difference in the boot process doesn’t end at the initial load.
During the boot process, the various file systems (listed earlier) are mounted, and the boot process stops
at either the login prompt or a graphical log in (depending on how you configured the system at
installation).
When the boot process stops at login, you'll be greeted with either the login: prompt or the GUI.
Regardless of whether it's text or graphical, you’ll provide your username (assuming you've set up a user
account) and then your password. If this is your first install and you haven't added a user, you will be
required to type (at the login prompt) root, followed by the root password you entered during the last
phase of the installation process.
If your machine is configured for text-based login, once you've logged in as user, you'll see another
prompt:
[username@localhost username]$
This prompt accepts all the various commands (either essential or nonessential) in Linux. One of these
commands is startx, which starts the Linux X Window System. The X Window System is the application
that allows the various Linux GUIs to communicate with the OS. The Linux GUI (as a standard Red Hat
6.0 install) has many features found in the Windows 95 environment (Table C).
TABLE C
Windows
Taskbar
Start menu
Desktop icons
Program menu
DOS window
Mouse pointer
Copy/Paste
Linux
GNOME panel or fvwm2 taskbar
GNOME menu or fvwm2 Start button
Desktop launchers
User menus/Application menus
Console terminal
Mouse pointer
Copy/Paste
Many Linux GUI and Windows features are similar.
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Shutdown
The Linux shutdown process is very similar to its Windows counterpart. If the Linux system isn’t shut
down properly, the file systems won’t be able to unmount properly, thereby forcing a check during the
next boot. This is similar to the event that Windows doesn’t shut down properly and must run ScanDisk.
To log out properly, you must go through the main GNOME menu and select Log Out. Once the Log Out
option is selected, you will be given another set of options: Log Out, Halt, and Reboot. To shut down the
system, choose Halt; to reboot the system, choose Reboot; and to log out, choose Log Out.
Another option included on the Log Out screen is Save Current Setup. It is always wise to select this
check box so that your desktop will return to its current state upon logout. In order to log out properly from
KDE, select Log Out from the main menu, and you will be returned to the command prompt. To reboot
from the command prompt, change to the root user (run the su command by typing su and pressing
[Enter]) and then provide the root password when prompted. Once you have root access, you will run one
of the following commands:
To reboot:
/sbin/shutdown -r now
To shut down:
/sbin/shutdown -h now
Once the logout process is successfully executed, the OS will begin to unmount the file system and,
depending on the option selected, begin the process of shutting down, logging out, or rebooting.
Basic file processes
Now, let's look at the basic tasks of computing. In Linux, there's almost always more than one way to
accomplish a task. In this primer, we’ll deal with both the command-line process and the GUI process.
Understand, however, that the command-line mode is much simpler and more efficient, but it’s often not
as user-friendly. (You actually have to type!) For the sake of this primer, we'll deal with only the basics:
reading files, copying files, deleting files and directories, searching for files and directories, changing a
file’s permissions, and renaming files.
In Windows, all of these commands are taken care of in a GUI environment. You can perform most of
these Windows commands by right-clicking the mouse or using the drag-and-drop operation. To perform
the above-mentioned file processes in a console-type Windows environment, the computer must be shut
down and restarted in MS-DOS mode. (I purposely do not mention the DOS window due to its inability to
function as a true console emulator.) Linux, however, has the power to perform most of these functions in
both the console and GUI environments. Why would you want to manage these tasks with the commandline interface when using the GUI is so simple? In console mode, these tasks can take on many
arguments and details that the GUI mode (in both operating systems) couldn't possibly handle. Using the
command-line interface, you can pipe output to other files (meaning you can take the output from your
commands and send it to a file to be analyzed later). You can also move around more quickly and not
overwhelm your processor with the load of the GUI. Another benefit to learning the command-line
structure is that it allows you to command and control machines remotely. With the help of secure shell
(or even the less secure telnet), you can log on to a machine and run commands as if you were sitting in
front of that very box.
C AND G
Throughout the following descriptions, each OS will be listed and each style will be represented with
either C (for command line) or G (for GUI). The Windows GUI will often refer to Windows Explorer, and
the Linux GUI will often refer to GNOME's GMC (GNOME Midnight Commander).
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Let's compare the basic manipulation of files.
Reading files
A key difference between Linux and Windows is the versatility that Linux has in reading files. Linux can
read any file, be it binary, hex, text, doc, wpf, and so forth. The list goes on and on. Linux also has a
number of different ways in which it can read a file (Table D).
TABLE D
Windows
None
Right-click open with (G)
Linux
less (C)
Right-click open with (G)
Linux offers different methods of reading a file.
The less command allows you to view the contents of just about any file. Let's say you have a .txt file
called budget.txt. In order to view the contents of that file, simply type less budget.txt, and the contents of
that file will appear on the screen. A word of warning: Typing less budget.txt works only if the file contains
20 lines or less. If the file is longer, you'll have to pipe the command to more. In basic terms, this means
you'll add the more argument to the command. By adding more, you'll see the file only one screen at a
time. In order to scroll down the listing, press any key to move down a screen. To get out of less, type q
for quit.
Like Windows, the latest Red Hat Linux has the GUI functionality associated with file manipulation.
Within the GNOME menu, there is an application called GMC, which is similar to Windows Explorer. GMC
produces the graphical interface to all files on the system. With the graphical interface, you can drag and
drop, right-click, and open files. To view the contents of a file in File Manager, right-click the file and
select View. This command opens the GNOME file viewer and displays the contents of the file. The
GNOME file viewer also enables you to perform string searches within a file, go to a particular line in a
file, and make a symbolic link to a file (similar to a Windows shortcut).
In the newer releases of Linux (i.e., Red Hat 7.1 and Mandrake 7.2), KDE2 is installed. KDE2 includes
the very powerful Konqueror, which is not only a Web browser (and a darn good one at that) but also a
file manager. The Konqueror file manager is very flexible and highly configurable—in fact, it can be set up
and used exactly like Windows Explorer.
There are many other ways to read a file in Linux, including various text editors and word processors.
Linux runs three office suites that make any Windows user feel right at home: WordPerfect, StarOffice,
and Applixware. WordPerfect surpasses Microsoft Word in the desktop publishing battleground. All three
Linux office suites behave exactly as a Windows user would expect them to behave. Surprisingly enough,
these applications will remove a great deal of the fear from using Linux.
Copying files
Copying files in Linux can be either a simple drag-and-drop operation or a few keystrokes away. Not only
is the command line for copying a file simple but it's also powerful (Table E).
TABLE E
Windows
None
Right-click drag and drop (Explorer) (G)
Linux
cp (C)
[Ctrl] drag and drop (File Manager) (G)
Linux offers different methods for copying files.
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Again, let’s work with our budget.txt file. Suppose the file currently resides in the /home/bob directory
and you want to copy it to the /home/bob/work directory. While in the /home/bob directory and at a
command prompt, type cp ~/budget.txt ~/work/, and the file budget.txt will be copied from /home/bob to
/home/bob/work. And just what does the ~/ mean? Basically, ~/ tells your system that you are in that
particular user's home directory. (The user is who you are logged on as.) Using ~/ is merely a way to
eliminate keystrokes. If you want to avoid confusion or you don't like to avoid keystrokes, you could type
the entire path of both directories (i.e., /home/bob and /home/bob/work).
The cp command is not limited to the current working directory. Let's use the same example, but we’ll
say you are in the /usr/bin directory. To copy the budget.txt file from the /home/bob directory to the
/home/bob/work directory, you'd have to type the entire path of both directories. Even from an obscure
directory deep within your system, you could type cp /home/bob/budget.txt /home/bob/work/, and the file
would still be copied exactly as commanded.
Similar to Windows 9x/Windows NT, Linux is able to copy files with a simple drag-and-drop procedure.
To copy files in the GNOME File Manager, hold down [Ctrl], click the left mouse button, and drag the file
to where you want it copied. (If you don't press [Ctrl], the file is moved and not copied.) Another easy way
to copy files with File Manager is to highlight the file by single clicking, go to the File menu, select Copy,
and use the Browse button to select your file's destination. This menu also enables you to open, copy,
delete, and move files.
Deleting files
Deleting files with any of Linux’s graphical file managers such as GMC and Konqueror is similar to
deleting files in Windows Explorer; select the file you want deleted and then select File | Delete. You can
also delete a file by selecting it and then right-clicking and selecting Delete from the resulting shortcut
menu.
From the early stages of Linux, the command-line interface has ruled. In order to delete files at the
command line, use the rm command. This exquisitely powerful command contains numerous options that
make it one of the most flexible methods of removing a file (Table F).
TABLE F
Windows
None
Right-click | Delete (Explorer) (G)
Linux
rm (C)
Right-click | Delete (File Manager) (G)
There are several ways to delete files in Linux.
To remove a file with rm, type (at a command prompt) rm filename, and the file will be deleted. This is
the most basic command. Now let's look at some of the options:




rm f filename: The force command forces the file's removal, ignoring nonexistent files and never
asking for a prompt.
rm i filename: The interactive command prompts you before any deletion—a very wise precaution
to take when you’re just getting started. Remember, a deleted file in Linux is just that—deleted!
rm r directoryname: The recursive command removes the contents of a directory recursively. What
actually happens is that the command will dive into a directory and remove its contents and will then
exit the directory and remove the directory itself. Be very careful with this command. Should you
execute rm rf / (as root), your entire drive will be deleted.
rm v filename: The verbose command provides an explanation of everything that’s being done
during the deletion.
Searching for files
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The Windows Find application is quite a powerful tool. Windows Find is relatively fast and accurate, and
it's as stable as a Windows application can be. Linux has a variety of options for find—both command-line
and GUI (Table G).
TABLE G
Windows
Find (G)
None
None
None
None
None
Linux
find (C)
whereis (C)
locate (C)
AfterStep's Find module (G)
GNOME search tool (G)
KDE find files (G)
Linux offers many different ways to search for files.
Let's examine the GUI applications first. The applications most similar to Windows Find are the
GNOME Search Tool and the KDE Find Files tool. You can find the GNOME Search Tool in the main
menu under the Utilities submenu. The KDE Find Files tool is found in the main menu. When the Search
Tool window opens, you’ll see two places to input text: The first area tells the application where to start
looking, and the second is the name of the file. Beyond the text entry is a very helpful drop-down list of
addendums you can use with the find command, such as Don't Search Subdirectories, File Owner, and
many others. These addendums expedite the process of searching a large disk. You can also use both
search tools to remove files.
AfterStep has its own version of the search tool that isn’t as elegant as GNOME's, but it’s just as
reliable and efficient. AfterStep's Search tool is located in the Root menu under Modules. When the
Search tool opens, you’re greeted with a window containing a single text area. Type the name of the file
and select Go, and the program will find the file. It's not as pretty as the GNOME Search Tool, but it’s just
as effective.
Changing permissions
Since the Linux environment is a multiuser environment, it’s necessary to add permissions to the OS for
security. Windows requires third-party software to achieve this effect, but it attains only a fraction of
Linux's simplicity and security. Permissions dictate who can and cannot read, write, or execute a file
(Table H).
TABLE H
Windows
None
None
None
Linux
chmod (C)
GMC (G)
Konqueror (G)
Linux offers multiple methods of changing file permissions.
Suppose that on your desktop machine at work, you have a document that is critical for you to complete
during a given week. However, it is well known throughout the office that one particular joker is fond of
hindering your progress. To prevent this from occurring, Linux sets up each user so that he or she
declares who can edit the user's files. In our example, the document is called work.doc (notice the
standard Word 97 extension that a program such as StarOffice can read and write), and the user is
named Chuck. Should Chuck want to keep anyone else from reading or changing work.doc, he would
simply set the permissions so that only user (Chuck) can read, write, or execute work.doc. To do this,
Chuck types (at a command prompt) chmod 700 work.doc. Let's decipher this command.
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You issue the chmod command to change the mode of the file. The next element, 700, is a bit more
complex, but once you understand it, it's a real time-saver. There are three types of users you want to
think about in Linux: user, group, and other. Each type of user is thought of in octal notation. In other
words, think of user in hundreds, group in tens, and other in ones. Each type of permission—read (r),
write (w), execute (x)—is given a corresponding number that is related to the type of user assigned
(Table I).
TABLE I
User
rwx
400 200 100
Group
rwx
40 20 10
Other
rwx
421
There are three types of users in Linux.
As shown in Table I, each number corresponds to both a permission (read, write, or execute) and a
user (user, group, or other). When you decide which permissions you want to assign, you simply add the
numbers together to form a command. For group to have only read access, the number is 40. For group
to have both read and write access, the number is 60. For group to have complete access, the number is
70. For example, Chuck wants to allow group to read the file work.doc (in addition to the existing
permission set detailed above) but not to write to the file. To do this, Chuck would add the number 40 to
the first number, so chmod 740 work.doc will allow user total access to the file, but group may only read
the file. Let's say that later, Chuck wants to change the permissions to add the write privilege for group.
Typing chmod 760 work.doc will do the trick.
There's another, easier way to add and remove permissions. With the plus [+] symbol, a user can add
or remove r, w , or x permissions to a file. So, to use the above example, chmod g+rw will give group read
and write privileges. The command chmod g-rw will remove the privileges.
Even simpler is the GUI of GNOME Midnight Commander (GMC). GMC allows you to set permissions
using the right-click menu. From the right-click menu, click Properties | Permissions, and you can easily
set permissions with the click of a button. It couldn't be any easier.
At first, assigning p
-user
desktop, it may be. But for a business that has many users, permissions can certainly save a great deal
of valuable work time and eliminate frustration.
Renaming files
The command line mv is a very easy-to-use command. Used with move, mv tells the OS, ''I'm moving this
file to this location and giving it this name.'' For instance, in order to rename the file work.doc (in the
/home/chuck directory) to work-backup.doc, you would type mv /home/chuck/work.doc /home/chuck/workbackup.doc, or even shorter, mv ~/work.doc ~/work-backup.doc (Table J).
TABLE J
Windows
None
None
Right-click | Rename (G)
None
Linux
mv (C)
cp (C)
GMC: Right-click file | Properties | Statistics
Konqueror: Right-click file | Rename (G)
You have several options for renaming files in Linux.
Like all good Linux commands, mv comes with a family of flags. However, using mv as a rename
command does not require the aid of flags. Note: Using the mv command will remove the original file. It is
wise to use the i flag to prevent overwriting important files.
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The cp command also acts as a simple renaming command without removing the original. This
command is great for making backups. To rename the above-mentioned file, type cp ~/work.doc ~/workbackup.doc, and both files will remain. When using the cp command (like the mv command) to rename
files, it's wise to use the i flag to prevent overwriting files.
To rename files via the GUI, think of Windows Explorer. GMC enables you to right-click a file and act
upon that file in numerous ways. To rename a file with this method, you’d right-click the file, choose
Properties, and rename the file in the File Name dialog box.
Using removable and nonremovable drives and media
Using a drive in Linux is somewhat different than in Windows. In Windows, you can select the drive and
view its contents, insert the floppy disk, and save, or you can insert the CD-ROM and install it. Linux, on
the other hand, requires a few more steps (at least in most distributions) (Table K).
TABLE K
Windows
None
None
Linux
mount (C)
floppy/cdrom icons (G) (GNOME and KDE)
Using a drive in Linux is a bit different than in Windows.
To many users, the mount command is merely another hurdle in the way of simple computing. Why
mount? Why doesn’t Linux recognize the drives (both floppy and CD-ROM) right away? Mounting a drive
is a way of telling a system (in very basic terms), "I need to use this device, and I want to read it from this
directory." You don't see the true necessity of mount until you are on a networked system where users
can share a single drive by simply mounting it (one user at a time).
Before we get into the actual mounting commands, we first want to set up the system so that users can
mount and umount drives. As root, type linuxconf and scroll down to Filesystem | Access Local Drive. In
this configuration tool, you will be able to edit the options of both the CD-ROM and the floppy drives.
To edit the /dev/fd0 (floppy) drive, select the name of the drive to open the configuration tool for that
particular drive. Under the /dev/fd0 tab, you'll want to do two things: First, you'll tell the system that the
type will be vfat. By doing this, your Linux system will automatically read and write to Windows-type disks
(thereby retaining their Windows 9x readability). Second, select the Options tab and then click the User
Mountable button so that the system does not require root access to mount the floppy drive.
Once the floppy is configured, move on to the CD-ROM (/dev/cdrom). Here, you have only one change
to make: You must make the file system user mountable. You handle this change in the same way as you
would the floppy drive.
The mount command also allows you to read many other types of file systems, including the Windows
9x VFAT system and the Windows NT file system. Let's assume that your system has either a Windows
partition or drive, as well as a Linux partition or drive. In order for your Linux system to read the Windows
partition, you must mount the system to a directory. In our case, we'll first create a directory (for our
Windows needs) called win. This directory will be located in the /mnt/ directory. At the command line, type
mkdir /mnt/win. Depending on where your Windows partition/drive is located, you'll use certain names for
the drive itself. Remember that the Linux naming system varies from the standard Windows naming
system. Typically, a Windows partition will lie under either /hda, /hdb, or /hdc. Let's assume that your
Windows drive is housed on the same drive as your Linux drive (/had) and was installed prior to the Linux
installation. To mount the Windows drive, at the command line type:
mount t vfat /dev/hda1 /mnt/win
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Now, to view or navigate around your Windows directories, cd into /mnt/win95, and you'll be in
Windows 9x. Linux is very powerful in that it allows you to copy to and from the Windows drive from
Linux—everything is readable. This directory is now treated like a standard Linux drive, and the typical
Linux commands will function (including cp, mv, ls, and less).
Both GNOME and KDE offer another route to mounting various drives that allows you to mount and
unmount drives via the GUI. Both environments create desktop icons for the floppy and CD-ROM drives
that mount the respective drives with a single click (KDE) or double-click (GNOME). Once the drive is
mounted, you’re greeted with a window that shows the contents of the drive. This window allows you to
drag-and-drop and associate an application.
To unmount the system using the desktop icons, you must right-click the icon and select Unmount
Device. The system will sync, and the drive will unmount.
GNOME also allows for the mount applets to be placed on the GNOME Panel. These applets act as
simple buttons that you can click to mount and unmount. The applets are better suited to users who will
be doing most of their work from the command line, while the icons are designed for the GUI lover. To
add these applets, right-click the GNOME Panel and choose Add Applet | Utility | Drive Mount. The
default drive applet is for the floppy drive, so when a second applet is added, you must change the
properties (by right-clicking) to tell the applet to mount the CD-ROM as opposed to the floppy.
REMEMBER TO UNMOUNT
When you've finished with the Windows drive or any mountable drive other than the Linux drive, it’s
very important to unmount this drive so the system can be shut down properly.
Some of the more recent distributions, such as Mandrake 7.2, include a utility called supermount that
allows you to access and remove floppy disks and CDs without having to run any of the cumbersome
mount commands. This, of course, is unique to some distributions. If you’re interested in this type of
functionality, you’ll want to select a distribution that includes this utility.
The desktop
Let's first take a look at what a Linux desktop is, and then we'll explore the particulars.
The basics
A Linux GUI-based system has multiple layers that make up its environment. On top of the Linux kernel
lays the X Window System. The X Window System acts as a mediator between the desktop GUI and the
kernel. According to the X main page:
“X Window System server distributes user input to and accepts output requests from various client
programs through a variety of different interprocess communication channels.''
On top of the X Window System lies the desktop environment. Two common desktop environments are
GNOME and KDE. Finally, on top of the desktop environment lies the window manager (WM). According
to the official AfterStep site:
“A window manager (briefly) is a program which controls the way various windows interact during an X
session.''
There are many Window Managers available, with Linux distributions and from various individuals and
companies. All of these are completely configurable environments that allow you to customize the
desktop to the limits of your imagination. Like other Linux components many of the Window Managers
include source code, which allows customization at a programming level.
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In essence, X allows the desktop environment to communicate to the kernel, and the window manager
allows the user to communicate to the desktop. By employing these components, Linux contains all of the
GUI tools that Windows has set as standard for the desktop GUI user. See Table L for a comparison of
the functionalities.
TABLE L
Windows
Taskbar
Start button
Desktop icons
Drag and drop
Linux
Kpanel (KDE) Panel (GNOME)
K button (KDE) Main menu (GNOME)
Desktop icons
Drag and drop
The Linux desktop offers the same functionality as its Windows counterpart, with added stability and efficiency.
Now we can compare the two popular desktops mentioned above.
KDE
KDE has, by default, all of the elements that comprise what is considered the standard desktop
environment:
 Taskbar
 User menus
 Clickable icons
 Configurable window elements
 Wallpaper and color configurations
 Launchable applications via the taskbar
 A clock
Like the whole of Linux, these configurations are limited only by the imagination.
Let's take a look at the largest visual component of the KDE desktop: the taskbar. Much like its
Windows counterpart, the KDE taskbar's most prominent element is the K button, which is the same as
the Windows Start Button. The K button is the menu on which most KDE applications can be found. Using
this menu, it is possible to conduct the entire Linux session without typing a single command on the
command line. This will make most Windows users feel more comfortable if they are migrating to a Linux
environment. Let's run through a quick session. This session will assume many of the components have
been preconfigured.
You want to check your e-mail? Click the K button, go to Internet, and then click Kppd, the Internet dialup connection application. Once kppd has connected to your ISP, again click the K button and choose
Internet. This time, click Kmail or Netscape, and you'll be off and running with your e-mail. Kmail is the
KDE mail client which is similar to other email clients such as Eudora or Outlook.
All applications within the KDE environment are run in a similar fashion. The K menu contains
everything you’ll need to run, configure, personalize, shut down, play, browse, find, and control, all with
the click of a button. The K menu user-configurable. You'll find the primary tool for configuring the menu
within K | Utilities | Menu Editor. This GUI application enables you to create new menu items within the
Personal menu entry that you can later add to the panel as clickable buttons.
The feel of KDE has brought Linux as close to a Windows-esque environment as possible. Much of this
success is brought about with the aid of the K panel. The K panel is a taskbar-like element that rests at
the bottom (or top or right or left) of the screen and contains the various menus, buttons, and clocks
native to KDE. This panel is highly configurable, going well beyond its Microsoft counterpart. Not only can
the K panel contain clickable icons (like Internet Explorer 4, which was added to Windows 95 and was
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then added to Windows 98), but it can also be hidden in multiple ways. To hide the K panel, you can take
the Microsoft-friendly route of using Autohide or use the KDE default of sliding the panel in and out.
The actual desktop space of the K environment is also very similar to its Microsoft counterpart.
Clickable icons are easy to use and configure, and they’re much more aesthetic than their counterparts.
Adding a new icon is as easy as a right-click: Just select New | Application and then provide the
requested information. KDE has the added bonus of being able to add a clickable URL icon or a handy
Mailto icon. For example, suppose you have a particular person you e-mail frequently, and you want to be
able to send that person an e-mail on a moment's notice. With KDE, this is not a problem. Right-click the
desktop area, choose New | Internet Address, give the icon a name (for example, the person's name),
click the URL tab, and in the text area, type mailto:EMAILADDRESS (where EMAILADDRESS is the
particular address where you wish to send mail). Once the information is complete, click OK. Now every
time you click that icon, K mail will open with the recipient's address ready to go.
GNOME
Like KDE, GNOME contains many of its own unique applications, utilities, and configuration tools found
on the GNOME main menu. Sporting the GNOME footprint, the main menu consists of the same menus
found in KDE, with the addition of a separate KDE menu entry and another level (fvwm) menu entry. So
extensive are these menus that, after months of operation and just plain playing around, there are still
many menus I have yet to discover.
Again similar to KDE, GNOME's desktop contains clickable icons that simplify your experience even
more. Upon installation, the icons are a mix of URLs (mostly Red Hat sites) and the GNOME File
Manager (GMC). Adding a new desktop icon is as easy as right-clicking the mouse and adding a new
launcher.
GNOME has made the task of adding desktop URLs even easier. While in Netscape Navigator, you
only have to move the Location button to the desktop using the drag-and-drop operation. This will create
an icon that you can double-click to open the browser or right-click to alter the properties (such as the
icon itself and the name of the icon).
The drag-and-drop operation has also been implemented into GNOME. On the desktop area, dragging
a file into a folder is accomplished in the same manner as in Windows. Click the left mouse button and
drag the file into the folder. All GNOME applications support drag-and-drop.
The GNOME desktop can also be configured as easily as KDE. The desktop can be rendered as close
to or as different from Windows as is desired.
Desktop configurations
Each Linux desktop is as unique as its owner. From the standard out-of-the-box to the fully tweaked and
twisted, Linux can please everyone. The standard Linux desktop is sure to satisfy any migratory Windows
user because it comes complete with a taskbar, a Start menu, and desktop icons. The fully-configured
Linux desktop will certainly please those who like their computing environment tailored exactly to fit their
needs and tastes.
For example, using a GNOME/AfterStep combination, you can call aterm with transparent windows and
with either tint or no tint. For example, the command:
aterm -tr -tint yellow -fg white -bg black +sb
will call aterm with a transparent background, yellow tint, white text, black highlighting, and a scroll bar.
Although this seems like a lot of command typing, you can easily type this in one of the AfterStep menus
(or even in a launcher icon in either GNOME or KDE).
This option allows you to see the wallpaper behind the window—an awe-inspiring effect indeed. The
standard GNOME terminal and the Kconsole can achieve the same effect of transparent windows.
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Each window manager also allows the integration of various themes into the desktop. A theme,
according to David Coulson (of themes.org), is:
“...considered to be a script and images which alter the way in which an application, window manager,
or toolkit looks, works, and feels.''
Each window manager such as; AfterStep, Sawfish, Enlightenment, Window Maker, IceWM, Blackbox,
FVWM2, and KWM, has its own themes, which in turn, all configure the Window Manager to different
extremes. The FVWM window manager stands on the lighter side of configuration with backgrounds, title
bars, and taskbars, while Enlightenment goes so far as to reshape windows. Each window manager
handles its theme installation differently. Some of the higher-end window managers, such as
Enlightenment and KWM, have applications that install the themes for the user. Here's a partial listing of
resources offering the best help on downloading various window managers and installing predefined
desktop themes:







themes.org
Enlightenment
AfterStep
FVWM
IceWM
KDE
Window Maker
Take a moment to visit these sites. You'll notice how varied the desktops are. This is the very reason
why making a head-on comparison of a Linux desktop and a Windows desktop is preposterous. All of the
window managers listed above will work in conjunction with Linux, and nearly all of them are
interchangeable with the various desktop metaphors (GNOME and KDE, for example).
When choosing your window manager, note the resource needs of each. It is a general rule of thumb
that FVWM has the smallest resource requirements while Enlightenment has the largest. With a Pentium
100 or less, you would be best to stick with the likes of FVWM. I would rank the window managers from
least resource-intensive to most as follows (this is, of course, untested conjecture): FVWM, IceWM,
Window Maker, AfterStep, Sawfish, KWM, and finally, Enlightenment. Although this list is untested, after
taking a quick look at the various sites, you will likely come to the same conclusion.
Each window manager has its own personality and way of doing things. Finding a perfect fit is simply a
matter of try-before-you-buy.
Program installation
To the uninitiated, installing or upgrading an application in Linux is a seemingly insurmountable task. This
is far from the truth, of course. One of Windows' strengths is also one of its weaknesses. The amazing
user-friendliness of the Windows installation method effectively hides the entire task from you. The
closest you get to being involved with an installation on a Windows machine is choosing the directory
path and possibly the various packages native to the program being installed. Linux, on the other hand,
allows you to work as removed or as hands-on as you choose (Table M).
TABLE M
Windows
Autorun
Setup – clickable(G)
None
Zip
Linux
None
Grpm (GNOME) – Kpackage (KDE) (G)
rpm (C)
tar and zip
Installing and upgrading applications in Linux is a relatively easy task.
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Let's begin the installation by looking at the packing tools. Windows has the Zip command; Linux has
tar and zip. Windows' Zip is simple; Linux's tar can be simple. In Windows, you download a third-party
program, usually WinZip or PKZip and usually as a trial version, and run its proprietary GUI to pack and
unpack archived applications and files. Linux has two different tools at its disposal: zip and tar. Both tools
come with nearly all distributions and are almost always cross-distribution. The biggest difference, and
most frightening to the new user, is that Linux uses the command line to pack and unpack files. Although
this process is intimidating at first, it quickly becomes second nature and is very versatile. There are also
GUI applications for pack and unpack available.
Let's work with an imaginary file: this_program-1.1.0.tar.gz. Notice the .gz extension? This extension
means that this archive has been compressed to make the file smaller. One very misunderstood fact is
that tar does not shrink the size of a package; it merely takes a group of files and/or directories and
archives them into one file, hence the term packing.
In Linux, when you come across a file that has been zipped, you will want to first unzip the archive.
Unzipping, in Linux, is achieved with a simple command. Using our sample file, the command would be:
gunzip this_program-1.1.0.tar.gz or gzip –d this_program-1.1.0.tar.gz
This command will extract the following file:
this_program-1.1.0.tar
Now you have the uncompressed archive file that is ready to be unpacked. Unpacking an archive will
explode the contents back to their original state.
Let's say that this_program-1.1.0.tar, in its unpacked form, has the following structure: The main
application folder is named /this_program, and the following files will be housed in the application folder:








README: A README file about the program and what it does
INSTALL: A README file describing the installation process
Fil
e_1: An application file
file_2: An application file
file_3: An application file
data_file: A data file
this_program: Either the install script (compared to Install.exe in Windows) or the application's run
script (compared to This_program.exe in Windows)
You will see the contents shown above when you execute the following command on the this_program1.1.0.tar file:
tar xvf this_program-1.1.0.tar
Yes, there are flags, or arguments, involved in the untarring of an application. The flags shown in the
above command are the most common of all the tar flags and mean the following:



x tells tar to extract files from the archive.
v tell tar to be verbose and display filenames.
f tells tar that the file following the flags is the file to unpack.
There are many more flags for the tar command. Thirty-one are commonly used, but the above three
are the basic flags. These arguments should get you through untarring most of your application files.
As stated earlier, tar merely unpacks the files; it does not, however, install the application. That task is
left to you. Once the archive is unpacked, the next step is to cd into the newly created directory (in our
example, this_program) and poke around to see what's what. In a Windows environment, README files
typically tell you where to purchase upgrades or how to contact the company, and occasionally it warns of
known installation issues or bugs. Linux README files offer a variety of information, and there is no
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standard file. Typically, a README file will contain general information about the application, show how to
build (install) the application, explain how to run the program, contain configuration variable/file listings,
show the location of source code, and provide author contact information. It's good computing practice to
read README files in Linux. Windows README files are generally safe to ignore; Linux README files
are not.
Now, let’s proceed to the installation. This topic is a bit more difficult to outline because every
installation that’s not an RPM is different. Although it would seem that you’d need near-programmer
status to install an untarred package, that is not true. Generally, the command configure or the one-two
punch of make followed with make install is the standard. However, there are exceptions. Again, this is
where the README files come in handy. Even better, if the programmer is smart, he or she will include
an INSTALL file that outlines the installation process. Note here a Linux convention is most files,
regardless of name, which are in all capital letters should be considered README files.
The make command is not an installation command. It is the command to compile an application from
the source code. Compiling translates source code into machine-readable binary files. The make
command is a convenient front end for compiling. It reads special files that assure the same compiled
version each time. When you've untarred an application, what you have done is unpack all the source
code for that program. With make, the source code is then translated into something the machine can
read.
Once the source code is compiled, the command make install takes this process one step further by
actually putting the new machine-readable code, or executable, into the default, or user specified location.
Once make install has accomplished its mission, return to the README file to find the executable
command. Linux does not use .exe files for executable programs; an executable file can have any name.
Often, Linux uses wrapper files or shell scripts to execute an application. So, in place of
This_program.exe, as in Windows, in the program directory you will see a file called this_program. To run
the program type:
$ ./this_program
In order to assure the program would be executable from anywhere, the new program directory would
need to be added to the shell variable PATH.
rpm
The rpm utility is a very powerful application that allows you to manipulate the installation and removal of
any package that has the .rpm extension. Many Linux distributions support the rpm utility. The rpm utility
is not limited to the installation and removal of packages. For the developer, rpm can also build. Of
course, build is a bit beyond the scope of this document, so I'll stick with install/remove.
With the latest distribution releases, rpm has been enhanced with nice GUI front ends. For example,
GNOME has gnorpm, and KDE has kpackage.
There is one thing you will want to be aware of when getting rpm packages to install onto your system:
rpm has many different flavors, and only one will work on your system. A typical Red Hat system uses
either the i386.rpm or the i686.rpm format. As long as you pay attention to the following instructions, you
don’t need to worry that you may destroy a system with the wrong flavor of rpm package.
The fundamental flags for rpm are shown below in Table N.
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TABLE N
Flag
-I
-v
-h
-q
-U
-R
-I
Action
Install
Verbose
Print hash marks for progress status
Query (ask the system what version of a package is installed)
Upgrade
List the packages on which this package depends
List files in package
There are several flags for rpm.
Note, you must have root privileges to use rpm. If you attempt to rpm a package as user, you will get an
error similar to this:
failed to open //var/lib/rpm/packages.rpm
error: cannot open //var/lib/rpm/packages.rpm
If you see this error, don’t worry. You can su to root and run the command again.
Installing with rpm
Installing with rpm is a very simple process. There are two ways in which to install: GUI or non-GUI. Let's
look at GUI first.
To install a package with Kpackage, one of the GUI rpm choices, you have four options:




Locate the package you wish to install in kfm (the K file manager) and use the drag-and-drop
operation to move it to a working copy of Kpackage.
Select a package file in kfm and start a new copy of Kpackage.
Use the Open menu items in Kpackage.
Select an uninstalled package in the package tree.
The simplest methods of installing packages are the first two methods using Kpackage. Here’s how to
perform each method:


Method 1: With Kpackage, open as root (su to root at a bash prompt and type Kpackage), open a
kfm window, and navigate to the package to be installed. Select the file you want to install and
use the drag-and-drop operation to move the file into Kpackage. Once the file is in Kpackage,
click Install, and the system will run standard dependency checks. If the package passes the
dependency checks, Kpackage will install the package. If there are errors, the report will offer
feedback. Although this method is not as quick as using the command-line interface, it is certainly
easier than remembering all of the flags and arguments.
Method 2: Open an su kfm by selecting K | System | File Manager (superuser mode)navigate to
the package to be installed, and select it. Kpackage will then proceed through the steps shown
above, starting with Click Install.
The command-line option for installing rpm packages is much more versatile than the GUI front ends,
because rpm is complex and has many options. The fundamentals of rpm, fortunately, are not complex.
Let's go back to our this_program example. Suppose you’ve downloaded this_program-1.1.0.i386.rpm
and are ready to install it. Here are the basic steps, with the necessary fundamental options.
The package you want to install, this_program-1.1.0.i386.rpm, is now located in your home directory.
The first step after opening a console is to su to root. As root, you will then issue this command:
rpm -ivh this_program-1.1.0.i386.rpm
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This line of code says is that you are going to install (i) with verbose (v) output and that you want a
printout of hash marks (h) to indicate progress. Now, let's say you already have the above program
installed, you want to upgrade to a recently released, newer version. In order to upgrade this program,
issue this command:
rpm -Uvh this_program-1.1.1.i386.rpm
The difference in the –U option indicates you want to upgrade an existing program.
Lastly, if you've found a better program, called that_program, that performs the same task as
this_program, you will probably want to uninstall this_program. Before you run the rpm -ivh on
that_program, you would uninstall this_program using the command:
rpm -e this_program
The –e option tells rpm to uninstall this_program.
Although this method may not seem like the easiest method to use, it is certainly the most efficient.
With the command line, it is also possible to rpm an entire group of packages. Let's say you are using
GNOME, and you want to take all the upgrades, download them, and install them. Create a directory
called gnome and dump all of these packages into that directory, cd into that directory, and then, as root,
run the following command:
rpm -Uvh *rpm
This command will check all dependencies and install all of the packages in the correct order and in the
right places. This is truly the most efficient means of upgrading a system. Once all of these packages are
upgraded, it is safe to delete the rpm files to save disk space.
System configuration
Within the Linux environment are many configuration tools that do many different jobs. Some of these
tools are all-powerful and encompass nearly every aspect of Linux configuration, while some are limited
to only one aspect. Most of the tools you will see are interfaces for script-writing commands, making Linux
configuration more point-and-click as opposed to hack-and-save. The tools for Linux configuration,
assuming Red Hat Linux, include:









linuxconf
Xconfigurator
XF86setup
netconf
sndconfig
netcfg
mouseconfig
timeconfig
kbdconfig
The tools are in order from top down of most functionality to least functionality. All of the above tools
must be run as root and should be used with caution.
linuxconf
The linuxconf utility, is launched by root, but clicking on the icon if it has been created or issuing:
# linuxconf
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linuxconf allows the administrator to handle all aspects of system configuration, from printers and
networks, to adding users. There is no equivalent to linuxconf in Windows. Figures C through H show
linuxconf under Red Hat.
FIGURE C
FIGURE D
Once you get below the network
configuration, you will see the user
accounts and filesystem configurations.
The top section of the linuxconf tool
holds many of the networking
configuration utilities.
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FIGURE E
FIGURE F
Beyond account configuration within
linuxconf lies configuration sections for
miscellaneous services, peripherals, boot
mode, and cluster configuration.
On the second linuxconf tab, you will see
configuration tools for the various control
panel subsets, the mounting and
unmounting of filesystems, control files,
date/time, and features.
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FIGURE G
FIGURE H
On the Status tab, you can configure the
various log files within your system.
The final linuxconf tab contains gurus
(wizards) that help you configure various
services.
In linuxconf, the most logical location to begin with is under Users Accounts | Normal | User Accounts.
This is where you would add, remove, and edit user accounts. Here, root can edit any of the existing user
accounts, add new user accounts to the system, disable user accounts, change the user’s group, change
the user’s password, add groups to a user, change the home directory, change the user shell, change the
user ID number, change the user mail alias, add mail redirect, and change the user’s privileges. For the
new user, the primary benefit of this section of linuxconf will be adding user accounts and changing
passwords.
Adding a new user with linuxconf is a simple matter of opening the Users Accounts section and clicking
Add. Once this section is open, you simply enter the proper information, such as login name and full
name. These are the only two required options. There are many other options, but for this discussion
simply adding a regular user is what is needed.
Once this information is correct, click Accept, which will then take you to the password prompt. A Linux
password must meet two requirements: It must be over five characters long, and it must not be based on
a word found in the dictionary. Capitalization is your friend: "Coffee” is not a valid Linux password, but
"cOfFeE” is valid, as is ”12drinkCoffee.” Use your imagination because it might be your best defense
against possible break-ins.
It is also important to note that linuxconf offers the ability to change users’ passwords. The regular
changing of passwords is a valuable security solution. In linuxconf, changing passwords is very simple:
You open the same tab you were just using and click the user whose password you wish to change. Once
you’re in the user’s account, click the Passwd button, enter the new password, and then reenter the new
password when prompted. In order to enable this change, you must click Act/Changes (for activate
changes), which brings up the Status Of The System tab. In this tab, click Activate The Changes. Once
you've activated the changes, you can quit linuxconf (by clicking Quit in the main menu and then clicking
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Quit again in the Status Of The System tab). If you have changed your own password, you will have to
exit out of your account and log back in for the change to take effect.
Note that it is also possible to change a user password in a terminal window, or in the console. A sample
console session for changing a user’s password might look like the following:
$ passwd
Changing password for fred
(current) UNIX password: chump
New UNIX password: jarhead
BAD PASSWORD: it is based on a dictionary word
New UNIX password: chumpzilla
BAD PASSWORD: is too similar to the old one
New UNIX password: cHuMpZiLlA
Retype new UNIX password: cHuMpZiLlA
passwd: all authentication tokens updated successfully
You should note the password text such as chump and chumpzilla would not be seen, they are normally
hidden. They are shown here for illustration.
The new password is now in effect. This is a much simpler method of changing a user password than
using the GUI. Console Linux is a beast that many new users avoid learning. However, it is to your benefit
to familiarize yourself with the basics of console commands and applications.
By default the passwd command changes the current user password. As root it is possible to change
another user's password. The command to change a user password is:
$ passwd <username>
root will not need to know the current password for the user, and will be able to assign any password to
the user.
The next most popular area of linuxconf is the networking sections. The linuxconf application contains
many sections that involve networking options. Depending on what type of networking you wish to
configure, you may have to visit various sections of linuxconf. The primary sections for basic networking
are:


Host name and IP network devices, under client tasks:
The administrator can set up the host name of the machine; the primary name and domain name;
the IP address; the Netmask; the Ethernet device; whether the machine uses Manual; DHCP; or
Bootp Network config mode; the I/O port; and the IRQ. These settings are for LAN usage, not
dial-up.
Special Accounts, under client tasks: The administrator can add or edit PPP, SLIP, or PLIP dialup connections. The setup of this section is very similar to the netcfg application. This section
closely resembles the Windows dial up networking application.
The linuxconf application goes well beyond dial-up networking, allowing the user to configure LAN,
Samba (Windows-to-Linux connectivity), and NFS networking protocols. In addition, linuxconf allows the
user to mount various file systems, configure sendmail (not for the weakhearted), server tasks, and many
other Linux systems. Windows does not have a comparable over-all administration tool.
netconf
Launch this command: netconf.
The netconf application is simply all of the networking configuration routines from linuxconf included in
one package, providing all network configuration tools in one place.
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netcfg
Launch this command: netcfg.
The netcfg application is another network configuration application that adds a few features to netconf.
With netcfg, the administrator can configure PPP, SLIP, PLIP, Ethernet, Arcnet, Token Ring, and Pocket
(ATP), as well as configure PAP authentication, Nameserver information, and Routing information. What
is missing from netcfg is the ability to configure NFS, Samba, and other crucial networking services.
Xconfigurator
Launch this command: Xconfigurator.
The Xconfigurator application gives the user or administrator the ability to configure the X Windows
environment in Linux.
Before we get into Xconfigurator, let's examine X itself—what it is and what it does. X stands for X
Window System, and X does not stand for anything but X. Read this excerpt from www.x.org (the official
X Window System site):
“History
The X Protocol was developed in the mid 1980's amid the need to provide a network transparent
graphical user interface primarily for the UNIX operating system. X provides for the display and
management of graphical information, much in the same manner as Microsoft's Windows and IBM's
Presentation Manager. The key difference is in the structure of the X Protocol. Whereas Windows and
Presentation Manager simply display graphical applications local to the PC, the X Protocol distributes the
processing of applications by specifying a client-server relationship at the application level. The what to
do part of the application is called an X client and is separated from the how to do part, the display, called
the X server. X clients typically run on a remote machine which has excess computing power and
displays on an X server. The benefit is true client-server and distributed processing.
Definition
The X Protocol defines a client-server relationship between an application and its display. To meet this
the application (called an X client) is divorced from the display (known as the X server). X further provides
a common windowing system by specifying both a device dependent and an independent layer, and
basing the protocol on an asynchronous network protocol for communication between an X client and X
server. In effect, the X Protocol hides the peculiarities of the operating system and the underlying
hardware. This masking of architectural and engineering differences simplifies X client development and
provides the springboard for the X Window System's high portability.”
X Window is a very powerful system and so requires a very powerful configuration application.
Xconfigurator is just that—a tool to configure the display properties of your system. The primary
configurations accomplished through Xconfigurator are the video card and the monitor. When running
Xconfigurator, the administrator needs to know the following information about the system:

Video card
Type
Memory
 Monitor
Refresh rate
Resolution
Vertical sync range
Linux can probe your system to assign default values for color depth and default resolution, and
oftentimes it’s best to go with the suggested settings. A big word of warning here: Choosing the wrong
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settings in Xconfigurator can do untold damage to your monitor. Use caution! Know your hardware like a
good user should.
XF86Setup
Launch this command: XF86Setup.
A braver cousin to Xconfigurator, XF86Setup offers the user a wider array of configuration routines.
From mouse to keyboard to video card to video mode to monitor to server settings, XF86Setup extends
Xconfigurator’s ability to configure the X Window client while offering a graphical user interface.
mouseconfig
Launch this command: mouseconfig.
The mouseconfig application is a very simple program that allows the user or administrator to configure
the type of mouse and whether or not to emulate a three-button mouse. In Linux, the third mouse button
is the middle mouse button and is used for pasting from window to window. If you have a two button
mouse only, Linux will emulate the third button when the left and right mouse buttons are clicked
simultaneously.
timeconfig
Launch this command: timeconfig.
Yet another minimalist configuration tool, timeconfig does one thing and does it well; timeconfig sets the
time zone for your system. Believe it or not, there’s a huge repository of possibilities within this tool:
countries, states, zones, you name it! There is also one other option—setting the hardware clock to
Greenwich Mean Time or GMT.
kbdconfig
Launch this command: kbdconfig.
This simple application allows the user to configure the type of keyboard being used. Most of the
options are language options, but a few alternative keyboard layouts are included.
Sndconfig
Launch this command: sndconfg.
The final configuration tool is sndconfig. The sound configuration tool is a bit trickier than what most
people are used to because it demands that the user know a bit more information about their sound card.
Within this configuration routine, the administrator will need to know such information as type of card, I/O
ports, IRQs, and DMAs. Often the application will detect the card, but frequently the detection is in error
and so the card won’t work. This tool is only supplied with Red Hat distributions.
Configuration files
The Linux OS has a keen sense of configuration. In fact, configuration is one of the many aspects that
sets Linux apart from all other operating systems. You've heard it said countless times: "Customization of
Linux ends with the user’s imagination.” Rarely has such a pithy quote been so true. The Linux desktop is
a marvel of customizable wonder. From shapes to colors to sizes, the flexibility of the system is endless.
But how is this configuration accomplished? How do the thousands of hackers/users/artists commit
those changes to the operating system? One very simple, and global, method is to use a configuration
file. A configuration file can take on many forms. Some of these files are resource configuration (.rc) files;
some are not. Regardless of nomenclature, the Linux configuration files are a powerful method used to
shape your system.
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Resource configuration files
A collection of useful resource configuration files might look like this:
.bashrc
.procmailrc
.xinitrc
The above files are hidden files, and each deals with different aspects of the systems. The .bashrc file
is the individual per-interactive-shell startup file; .fetchmailrc contains the information your system needs
to retrieve mail from your ISP server; .pinrc is the configuration file for the Pine mail system; and
.procmailrc is a very powerful file for handling the various routing routines for procmail.
Let’s look at the .bashrc file in detail:
.bashrc
# .bashrc
# User specific aliases and functions
# Source global definitions
if [ -f /etc/bashrc ]; then
. /etc/bashrc
fi
HISTSIZE=50
stty erase "^H"
alias AS="cd /usr/share/afterstep/start/"
The .bashrc file has long been touted for holding mystical power within the Linux environment. The
above .bashrc file is an out-of-the-box, unconfigured file. This example, of course, does not show the
power of the .bashrc file. Let's break it down and see just what we can do with .bashrc.
The first three lines of this file are comments. Comments are lines of code that do not interact with the
system but give the user information about either a line of code or the file itself. The first uncommented
line
if [ -f /etc/bashrc ]; then
. /etc/bashrc
fi
is an if statement that searches the /etc directory for a .bashrc file. If the system finds a .bashrc file in
/etc, it will use that file for the resource configuration. However, if the system does not find /etc/bashrc,
then it will then go to the ~/ directory and use the ~`/.bashrc file local to the user.
Following the if statement are all of the user-applied configuration files. Of these files, the most useful
are history, aliases, and the ever-popular backspace configuration.
The line
HISTSIZE=50
defines the number of command lines that bash will hold in memory. (You'll see these memorized
commands at a bash prompt when you use the up or down arrow.)
stty erase "^H"
This line from .bashrc can solve a lot of headaches in bash. The Backspace and Delete keys have
created much confusion in the Linux community, and with a simple hack of the .bashrc file, each bash
prompt you open will bind the erase (or delete) function to the Backspace key (^H).
The final line in our .bashrc example offers undoubted relief from typing the myriad of lengthy
commands used in Linux. Since my initiation into Linux, I have used the command cd
/usr/share/afterstep/start countless times. In order to shorten those keystrokes, I put an alias into my
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.bashrc file. An alias, according to Linux in a Nutshell (O'Reilly Publishing: ISBN 1-56592-585-8), "assigns
name as the shorthand name, or alias, for command."
Let's say for the sake of example that instead of typing cd /usr/share/afterstep/start over and over and
over, we want to simply type AS (we can't use as because that is the command to call the GNU
assembler). In this case, go to your favorite editor and open that .bashrc file. The alias we are about to
enter will go at the end of the file (below the last entry) and will look like this:
alias
AS='cd /usr/share/afterstep/start'
As you can see, creating the alias is as simple as giving the new name a title and setting that title equal
to the desired command.
.xinitrc
According to Running Linux by Matt Walsh (O'Reilly Publishing ISBN: 1-56592-151-8), the .xinitrc file is a
"shell script containing X clients to run." The .xinitrc file is located in the user directory /home/USERNAME
and is used by X Window to call user-specified programs that are to run as the X Window System boots.
When the command startx is run, the X server begins its startup process and runs the commands found
in the .xinitrc file. These commands range from calling a desktop environment to calling a window
manager, to calling various programs and setting program environments (such as geometry and color). A
typical .xinitrc file looks like this:
!# /bin/sh
aterm -tr -fg white -bg purple -e pine & #to startup pine at X boot
/sbin/ifup ppp0 & #to bring up dial-up connection at X boot
afterstep & #to start window managers (afterstep)
exec gnome-session #to begin desktop environment (gnome)
This file is a very basic example of the power of .xinitrc. What you see here, in order of execution, is a
call to open pine, followed by a call to start the dial-up process, followed by a call to begin the window
manager AfterStep, and finished with a call to begin the GNOME desktop. Take note of the ending
ampersand [&] characters. The & following a line in the .bashrc file tells the system to go to the next line
and not wait for the application to launch. This is a simple way to make the startx process more efficient.
The number of applications that you can begin upon starting X Window (via .xinitrc) is unlimited;
however, take note that the more applications called from .xinitrc, the slower the boot process will be. The
best philosophy, with regard to .xinitrc, is to call the programs most often used or critical to the system.
With this method, the boot process will be more efficient, and X Window will be ready to roll with whatever
application you need to run. The addition of the dial-up command (/sbin/ifup ppp0) within .xinitrc is a nice
touch and ensures you a connection to your ISP when your GUI begins.
.procmailrc
For an introduction to the .procmailrc file, read ”All the wonders of procmail, part 1” and “All the wonders
of procmail, part 2: Lockfiles and nondelivering recipes.” Primarily, that discussion focused on playing
distinct sounds when various e-mails arrived via the procmail routine. For this discussion, we’ll focus on
using the .procmailrc file to redirect mail to specific mailboxes.
The .procmailrc file begins with the configuration of the user-defined inbox:
MAILDIR=$HOME/mail
#you'd better make sure it exists
DEFAULT=$MAILDIR/linux
#completely optional
#LOGFILE=$MAILDIR/from
#recommended
As a refresher, the .procmailrc sound configuration looks like this:
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:0:
* ^TO.*linux@techrepublic.com.*
| cat >> /home/linux/mail/linux ; esdplay ~/sounds/w_strange.wav
This code tells the system, “When mail comes into /home/linux/mail/linux and it is addressed to
linux@techrepublic.com, play the .wav file w_strange.wav.” This is a very simple method to alert the user
when mail has arrived from a certain someone.
Let's make this .rc file more useful. Let's say you’re using procmail to retrieve e-mail, and a vast
majority of the mail is split up among mailing lists. A simple way to filter those lists is to use procmail to
sort them. We'll use redhat-list@redhat.com (the Red Hat mailing list) and gnome-list@gnome.org (the
GNOME mailing list) as examples.
The first task is to send all of the redhat-list mail to its own folder, which we'll call redhat.
:0
^From.redhat-list@redhat.com
redhat
And the next example, gnome-list@gnome.org, will filter to its own folder, called gnome:
:0
* ^From.gnome-list@gnome.org
gnome
This particular filtering system can save a great deal of time and effort in the war against digging
through tons of mail, as well as getting rid of spam. With the procmail filtering capabilities, it’s possible to
toss known spammers into what has been called a killfile. Let's create a little trash compactor for
spammers:
:0
* ^From.spamers@address.com
/dev/null
Ker-flush!
Above and beyond the resource-configuration files, Linux uses a number of other very important
utilities. The X Window configuration relies heavily on a file called .Xdefaults. The .Xdefaults file allows
the user to add many (and various) configurations within one source. From aterm to xterm, from Netscape
to StarOffice, the .Xdefaults file configures them all.
Here’s a sample from .Xdefaults:
! Parts (C) 1996 By Greg J. Badros gjb@cs.duke.edu
! You may use this file as specified under the GNU General Public License
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
! emacs, xemacs
emacs*Background: DarkSlateGray
emacs*Foreground: Wheat
emacs*pointerColor: Orchid
emacs*cursorColor: Orchid
emacs*bitmapIcon: on
emacs*font: fixed
emacs.geometry: 80x25
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
! xterm (and friends)
Netscape*background: black
Netscape*foreground: green
Netscape*troughColor: green
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Netscape*XfeToolBar*highlightcolor: yellow
Netscape*blankBackground: black
Netscape*cellBackground: green
xosview*background:
aterm*scrollBar:
aterm*Foreground:
aterm*Background:
black
false
#FFFFFF
#000000
This segment represents the beginning one-fourth of an .Xdefaults file that has been modified to add
Netscape, xosview (a resource monitor), and aterm (a console emulator). One of the more eccentric
aspects of the .Xdefaults files is the use of capitalization, which is crucial for any of the configurations to
take effect. Take note of the capitalization of the word scrollbar: scrollBar. Without the proper syntax, the
X Window System will not pick up on the configuration.
The typical setup of the configurations within .Xdefaults is:
application*configuration:
flag
The standard configurations for .Xdefaults are: background (3-D objects), foreground (text), troughColor
(scrollbar trough), blankBackground (an empty window), scrollBar (this is a Boolean flag—true or false),
cursorColor (color of the cursor when in the window), and geometry (size of window). Many other
applications carry program-specific configurations, and they can be found in either that program’s man
page or README file.
It is also quite possible to add a background image to certain console emulators; rxvt allows the use of
.xpm files as background images that can be configured with the .Xdefaults file. The stock .Xdefaults file
will not contain any references to rxvt, but putting them in is an easy matter of adding the following entry:
rxvt*backgroundPixmap:
/path/to/.xpm
Note that it’s necessary to implement the .xpm file format for the background image. Configuring the
rxvt term to behave with this attribute is an interesting way to add a bit more spice to the desktop. Be
warned, however, that this configuration will use up more of your precious resources.
The number of resources you can use to configure X Window is limitless. I’ve given you only an
introduction to the vast world of user personalization within the Linux desktop. Any time a new application
is installed onto a machine, a wise user will look to see if an .rc file has been implemented into the design
scheme. If the .rc file has been used, then configuration is a snap.
Network configuration
A small home network can be assembled with the following hardware:




Two computers either preinstalled with Linux or available for a Linux installation.
Two network interface cards or NICs. Be sure to check the compatibility of the cards you would
like to use before purchasing them. Most Linux distributions recognize most common cards, but
some will not work. A common card, the 3c59x will be assumed for this example.
One network hub or switch. A switch is helpful to reduce network traffic.
Cables to connect both machines to the hub or switch.
The installation of this network is a very simple process. To cover all possible scenarios, we will be
looking at both a network setup from the very beginning of the OS install and a network setup post-install.
Neither method offers any advantage over the other, with the exception that one method already has a
jump start on OS configuration and familiarity. This will not, however, be a vehicle for familiarization with
the OS itself. I am making the assumption that you have a basic understanding of Linux and can run such
applications as telnet, ping, and ftp.
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Preinstall preparation
Very little preparation is necessary for the small home network configuration. Most of the work will be
done during the software installation and configuration. However, there is one easy task that might make
things go a bit smoother. You should first come up with names for your machines and then assign each
name an IP address. The IP address you want to use must be in one of the private ranges, so you'll want
to use something like 172.22.X (where X is unique to each machine on the network). Other ranges
include 192.168.X.X and 10.0.0.X.
Many networking products, such as cable modems and wireless gateways, automatically default to the
192.168.1.X range. Be sure to check with your ISP or broadband provider to avoid any conflicts, or preconfigure required ranges and names.
Let's say you have two machines you are planning to network together. One machine you call Buffy and
the other you call Angel (please forgive the reference). If Buffy is to be your main machine, then you
might want to assign it the 172.22.1.1 IP address and give Angel the 172.22.1.2 IP address. This
numbering system is simply for reference sake and makes it easier to remember that your main machine
is 1 and your secondary machine is 2. Actually, all this is rather pointless since we’ll eventually have the
machines set up in such a way that they will recognize the command ftp Buffy as opposed to needing to
remember that Buffy is 172.22.1.1.
On to the install
The hardware itself is rather easy to install. Typically, these older NICs will be either PCI or ISA slot-type
cards and will plug in as simply as a modem. Once the card is in and the machine is reassembled, you
can run your cable. It's actually easiest to have the machines side by side for testing purposes—this
saves a lot of running up and down stairs or down hallways in order to type ping Buffy or check on a load.
So, put the machines side by side, plug in one end of the twisted pair cable, and then prepare your hub or
switch.
Now you’re ready to run cable to the hub or switch. Installing the hub or switch is a simple matter of
plugging in the power and the twisted pair cables, and it is ready to accept data transfer. Depending on
whether or not your machines are up and running at this point, you may or may not have signal lights on
your hub. Don't worry yet. Occasionally you must tweak the BIOS, to disable PnP if you're using Linux
only.
Once the cards are installed, the hub or switch is powered up, and all of your cable is run, it's time to
configure. The first route that we will discuss is the preinstalled system configuration. Later we will look at
configuring a net during install.
As mentioned above Linux offers both GUI and character based configuration tools. We'll examine
several aspects of both and a combination of the two.
The first step in configuring your network is to run netcfg. Most everything you will do in netcfg can be
done in linuxconf, as well.
Once netcfg is running, the first steps will involve the Interface tab. From the Interface tab, click Add
and then Ethernet. Now, do you remember the IP addresses we discussed earlier? Here's where you'll
use them. For the new device you are about to configure, you must type the IP address you wish to
assign to that particular machine in the IP text area. For instance, you are running netcfg in Buffy you will
enter 172.22.1.1 in the IP area. Once you've entered this number, simply tab down, and the other
numbers are filled in for you. Next, select both check boxes to allow the interface to activate at boot time
and to allow any user to (de)activate the interface. Now you're finished. Click Done and then Save (when
the next window pops up).
The next step in configuring this simple network involves going back to that all-powerful tool, linuxconf.
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What we are going to do is set up a very basic Linux-to-Linux network. Our goal is the ability to ftp,
ping, telnet, and perform remote login. Within this setup, we won’t be dealing with NFS or Samba.
Eventually, we’ll cover network printing.
The first section to focus on in linuxconf is the basic host information. Here, you will more than likely
see the information you entered into netcfg. There are some additions to make however. Let's doublecheck our setup.
On the first tab in the Host Name And IP Network Devices section, you should see the name you gave
the machine—Buffy. If Buffy is not in the hostname box add it here. With the host name correct, move on
to the next tab—Adapter 1. In the Adapter 1 tab, you should see all the information for the card you set up
in netcfg: Primary name and domain: Buffy; IP Address: 172.22.1.1; Netmask: 255.255.0.0; NetDevice
eth0; kernel module: 3c59X. Once all of this information is correct, activate these changes to linuxconf
and move on to the first necessary script changes.
The files you will be dealing with reside in your /etc directory, and only root can manipulate them. As
usual, take caution when working around as root. The files you want to edit are hosts, hosts.allow,
hosts.equiv, and hosts.lpd (for printing). The first file, hosts, is a listing of hosts on your network which will
translate from the name to the IP address. The first line:
127.0.0.1
localhost
is necessary and is the loopback name and number. Do not tamper with this line. Following this line,
you will add in the IP addresses and names of all the machines on your network. So, for our example,
enter:
172.22.1.1
172.22.1.2
Buffy
Angel
Once you've typed these entries, save and exit the editor.
The next file we must alter is hosts.allow. This file tells your local machine which networked machines
have which privileges. More than likely, this file will consist of only approximately five commented lines,
meaning that they are not read by the compiler or the application.
The line you want to add in hosts.allow is:
in.ftpd, telnetd: 172.22.1.1, 172.22.1.2
This tells your machine that both Buffy and Angel have ftp and telnet privileges. It is important to note
that this example should be used only for a local network. If your network will interface with the Internet,
more secure connections are available with ssh and scp. Both telnet and ftp are considered security risks
since user name and password are transmitted as clear text.
In order to add a bit of preventive security, set up the hosts.deny file so that outsiders cannot use the
services, local to your new network, that could wreak havoc upon your machines. The hosts.deny file is
very simple:
ALL:ALL
This file will keep all outsiders from using either the ftp or telnet daemons.
This method is, of course, no replacement for solid firewall or ipchain ruleset; however, it is a quick fix
that will keep a minimum of security on your net.
Next we add or edit the file called hosts.equiv. This file acts as a secondary checkpoint for your system.
When your remote machine attempts to telnet or ftp into the local machine, the local machine makes a
check on hosts.allow to see if the machine in question has permission, then it makes a quick stop at
hosts.equiv for a secondary check. This file will contain only the name(s) of the remote hosts—in our
case, Angel.
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Once this last file is finished, you will then have to move over to the other machine (we're calling it
Angel) and make the same alterations, keeping in mind the correct IP address and the substitution of
Buffy for Angel in files like hosts.equiv.
The final step is getting the ftp daemon running. By default, this process will not be in the background.
The easiest method is to download wu-ftpd . Use an Internet search engine to download the latest
version. Most distributions also include a native ftp and telnet daemon.
Once the remote machine is properly set up, it's time to test your setup. At this point, depending on
your hub or switch, several connection lights are probably lit, indicating working connections between the
hub and the NICs.
Now, for the test. At a command prompt, type:
ping localhost
If all is well, you should start seeing something like:
64 bytes from 127.0.0.1: icmp_seq=0 ttl=225 time=0.1 ms
repeatedly displayed. If this is working, press [Ctrl]C to escape.
Now we'll test the host names. Once again, using ping, type:
ping Buffy
You should get the same feedback, with the IP address assigned to Buffy. If that's the case, you are
connected to your local machine. Escape this process, and we'll try to ping the remote machine:
ping Angel
should return to you the same output with the IP address assigned to Angel. If so, success!
Let's get fancy:
telnet Angel
If all is well you should be greeted with a login prompt:
login:
Here you enter the username that exists on the remote machine. You'll then be asked for the
username's password. Once you are logged in to that machine, you can move around and run console
processes as if you were sitting in front of the machine.
Now comes the big test: ftp. At a command prompt, type:
ftp Angel
If all is well, and the ftp daemon is running correctly, you should be greeted with a name:
(Angel:USERNAME): prompt
where USERNAME is the username of the machine you are working with. Be aware that ftp can
sometimes be flaky. Here, type the username you want to use to log in and, when asked, enter the
password for that user. Sometimes ftp will work right off, sometimes not. If the ftp login fails, type user at
the prompt and then, when asked, enter the username and the password. You should now be logged into
the remote machine via ftp.
Should you not be able to ftp into the remote machine, you should first double-check the files that you
altered or created. If these all check out, then more than likely the ftp daemon is not running correctly. If
this is the case, reboot your machine to get the ftp daemon up and running. From here on out, the ftp
daemon should begin running at boot.
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As I said, ftp is rather tricky at times. The command-line structure is a bit hard to master (with get and
put). Instead of running a tutorial on ftp, I will direct your attention to gftp (in the GNOME environment).
With gftp, you can simply go to the Remote section, choose the Connect Manager, fill in the hostname (in
our case, Angel), the username, and the password, and click Connect. Once you are logged in to the
remote machine, it's all click and move from there. Copying files from machine to machine couldn't be
easier.
Without gftp (or another front end to the ftp command), you must navigate the command line. Actually,
ftp is not horribly difficult to grasp. The command get (when already ftp'd into a machine) “gets” a file from
a remote machine to a local machine. The command put takes a file from the local machine and “puts” it
onto a remote machine. A command-line ftp transaction, sending a file (thisfile.txt) from Buffy to Angel,
would look like this:
ftp Angel
username:
password:
USERNAME
PASSWORD
ftp> put (enter)
(local-file) thisfile.txt (enter)
(remote-file) thisfile.txt (enter)
There are many other aspects of networking we have not touched on. Most of these areas (IP
Masquerading, NFS) are a bit more complex and sometimes require kernel manipulations. The nature of
this document, however, is a primer, so we'll discuss these topics later.
Maintenance
Surprisingly enough (and quite unlike its Windows counterpart), Linux requires little-to-no maintenance. In
the Windows world, routine maintenance such as defragmenting the hard disk, scanning for viruses, and
checking the hard disk is a regular task. The Linux native file system Extension 2, or ext2 for short, was
written in such a way that it does not allow the traditional holes that the Microsoft FAT16 and FAT32 file
systems allow. The ext2 file system manages to keep all file blocks contiguous so that any time a block of
data is placed back into hard disk storage, it is placed next to another file. This system keeps the hard
drive from filling up with holes—thus no fragmentation.
The Linux ext2 file system has an equivalent to the Windows Scan Disk utility. This equivalent is called
file system check (fsck) and is used primarily by the system itself, as a background maintenance tool that
keeps blocks of data from duplicating. It also checks for the standard errors on a disk drive. Below is an
explanation of fsck.
fsck
As I said, fsck is a Linux utility used to check and repair the ext2 file system. There are many situations
that could arise to call for the invocation of fsck. Such problems include an unclean shutdown of the
system (i.e., a power failure) or a system crash.
From the fsck man page we find:
“fsck is used to check and optionally repair a Linux file system. filesys is either the device name (e.g.,
/dev/hda1, /dev/sdb2) or the mount point (e.g. /, /usr, /home) for the file system. If this invocation of fsck
has several filesystems on different physical disk drives to check, then fsck will try to run them in parallel.
This reduces the total amount of time it takes to check all of the filesystems, since fsck takes advantage
of the parallelism of multiple disk spindles.”
Before we get into outlining fsck's ability to save a file system, let's look at its ability to simply check a
system. It is sometimes necessary to check the Linux file systems for consistency. Think of this check as
MS-DOS's Scan Disk. The fsck check will run a scan of the entire file structure and report back its
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findings. Typically, the findings will only pertain to noncontiguous, or fragmented blocks of data. There
can, of course, be other errors: bad or duplicate blocks, incorrect block count, Inode bitmap differences,
and incorrect Inode counts.
In order to run a check on your system close the window manager and log into the console as root, or
open a terminal window, and su to root. As root, you will have to run a check on an already mounted file
system; if any errors are found (and corrected), you will have to reboot the system. You will receive a
nasty warning message when attempting this check, so don’t proceed if you are afraid of disabling a
critical system. Generally there should be no problems with this check; however, there are exceptions to
every rule. Execute this command:
/sbin/fsck -t ext2 /dev/hda5
and you will begin the following session:
Parallelizing fsck version 1.14 (9-Jan-1999)
e2fsck 1.14, 9-Jan-1999 for EXT2 FS 0.5b, 95/08/09
/dev/hda5 is mounted.
####WARNING!!! Running e2fsck on a mounted filesystem may cause SEVERE filesystem
damage.###
Do you really want to continue (y/n)? yes
/dev/hda5 was not cleanly unmounted, check forced.
Pass 1: Checking inodes, blocks, and sizes
Deleted inode 164077 has zero dtime. Fix<y>? yes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
Block bitmap differences: -2071 -2072 -2073 -2074 -2075 -2076 -2077 -91734 -91735 91736 -91737 -91827 -91828 -91829 -91830 -91831 -91832 -93664 -93665 -93666 -93667 93668 -656772 -656773 -656774 -656775 -656776 -656777 -656778 -2205683 -2205684 2205685 -2205686 -2205687 -2205688 -2205689 -2426413 -2426414 -2426415 –2426416
Fix<y>? yes
Free blocks count wrong for group #0 (5814, counted=5821).
Fix<y>? yes
Free blocks count wrong for group #11 (5895, counted=5910).
Fix<y>? yes
Free blocks count wrong for group #80 (0, counted=7).
Fix<y>? yes
Free blocks count wrong for group #269 (6200, counted=6207).
Fix<y>? yes
Free blocks count wrong for group #296 (6, counted=10).
Fix<y>? yes
Free blocks count wrong (1005747, counted=1005787).
Fix<y>? yes
Inode bitmap differences: -164077
Fix<y>? yes
Free inodes count wrong for group #80 (1809, counted=1810).
Fix<y>? yes
Free inodes count wrong (673732, counted=673733).
Fix<y>? yes
Once this check has run (the above check ran into some errors), you will be given a report such as:
/dev/hda5: ***** FILE SYSTEM WAS MODIFIED *****
/dev/hda5: 88123/761856 files (1.5% non-contiguous), 2038341/3044128 blocks
If you receive the File System Was Modified report, it is crucial that you reboot the machine. Once you
reboot the machine it is a good idea to run fsck again, to be sure all errors have been found.
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You can run this type of check on a regular basis, but is not necessary to do so. One of the ways in
which Linux is smarter than many other operating systems is that it allows only so many boots before it
forces this check upon the system. Once you have reached that limit, you will get a message like
Maximum Mount Count Reached, Check Forced. This is standard operating procedure and should be
allowed to run its course.
But what if you run into a problem and you cannot boot your system? Generally with these problems, if
they are block errors, you will be prompted to log in as root and manually run a check. The warning,
however, does not give you all the gory details. Although the first check you should run is a standard
check (simply type fsck as root), it’s important—and sometimes imperative—to run an interactive check
as we did above. An interactive check allows the administrator to answer questions in order to fix any
problems. However, by running the standard check, fsck, the system will report back if there are any
block-type errors that are in need of repair. Should there be block-type errors, you can then run the
interactive check to take care of any problems.
Viruses
While Windows is a victim of countless viruses, Linux rarely experiences them. It’s very difficult for a virus
to be effective in such an environment because of the likely need for root access. There are a many
files—critical files—that only root has both read and write access to and a virus running under a regular
user account would not be able to alter them.
Needing root access is not the only hurdle for the proliferation of a Linux virus. The primary
transportation method of viruses is in either macro or executable form via e-mail. Since Linux does not
use .exe files and the macro languages are not compatible with it, the spread of the common virus is even
less of a hazard. As with Windows, proper security, and regular backup are good ways to minimize the
damage caused by a virus.
Help systems
Since Linux is an Open System OS, help systems are abundant. The primary help systems in Linux come
in the form of man pages, How-tos, and the Linux Documentation Project (Table O).
TABLE O
Windows
Help files
Linux
Man pages
How-tos
Linux Documentation Project
There are multiple Linux help systems.
Man pages
Man pages are to Linux what help files are to Windows—but with a twist. Most programs that are installed
onto Linux include what is called a man page (manual page). In truth, man is a program that formats and
displays the online manual pages.
From the man man page (you read that correctly):
“This version knows about the MANPATH and (MAN)PAGER environment variables, so you can have
your own set(s) of personal man pages and choose whatever program you would like to display the
formatted pages. If section is specified, man only looks in that section of the manual. You may also
specify the order to search the sections for entries and which preprocessors to run on the source files via
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command-line option or environment variables. If name contains a /, then it is first tried as a filename, so
that you can do man ./foo.5 or even man /cd/foo/bar.1.gz.”
The man pages are somewhat of a philosophy on their own. All man pages are set up with the same
information:







Name: The name of the command/application/program
Synopsis: How the command or application is invoked
Description: A brief description of the command/application/program
Options: Command flags and arguments that can be passed to the command/application/program
Author: The writer of the man page
Files: Related files (related to the command/application/program)
See Also: Related applications/man pages
One thing to keep in mind is that man pages are typically set up by and for those who write and develop
for the Linux OS. Because of this, the files seem rather cryptic. Without some knowledge of flags,
arguments, and command-line structures, the man pages will seem rather useless to the uninitiated. The
man pages, however, are a very simple beast to tame.
The primary hurdle for understanding man pages is knowing when to use them. The best reason for
using man pages is not learning the rudiments or fundamentals of a command/application/program, but
exploring the details of an application. For instance, instead of learning how to use the command fsck, a
user would read man fsck to learn the details of the command arguments and flags.
When examining the man page for fsck, the user learns about such arguments as these:






-R: When checking all file systems with the A flag, skip the root file system (in case it's already
mounted as read-write).
-T: Don't show the title on startup.
-N: Don't execute; just show what would be done.
-P: When the A flag is set, check the root file system in parallel with the other file systems. This is
not safe to do, since if the root file system is in doubt, files like the e2fsck980 executable might be
corrupted. This option is mainly provided for those systems administrators who don't want to
repartition the root file system to be small and compact (which is really the right solution).
-s: Serialize fsck operations. This is a good idea if you are checking multiple file systems and the
checkers are in an interactive mode. Note: e2fsck(8) runs in an interactive mode by default. To
make e2fsck(8) run in a noninteractive mode, you must either specify the \p or \a option if you
wish for errors to be corrected automatically or the \n option if you do not.
-V: Produce verbose output, including all file system-specific commands that are executed.
Of course, in order to use these flags, you must know how to run the basic command itself. At the
beginning of the man page, you see the following:
SYNOPSIS
fsck
[
-AVRTNP
]
[
-s
] [ -t fstype ] [ fs-options ] filesys [ ... ]
This explanation provides a map of how to use the command and the various arguments and switches.
Here’s the breakdown:





fsck: This is the actual command.
[ -AVRTNP]: These are the main options for the command. Generally a minimum of one option is
required.
[ -s ]: This represents the secondary options. These are typically optional.
[ -t fstype]: The t option is set up for describing a type of file system (such as when mounting a
system).
[ fs -options]: This is yet another optional argument. In this case, it defines whether the fsck
session will be either automatic (-a) or interactive (-r).
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Each command will have a different command/argument setup because of the varying nature of the
command structures. Fortunately, the man pages are all set up in the same manner. If you have a basic
understanding of how the Linux command line works, the man pages are a snap to translate into a
useable form.
How-tos
Linux has come a long way, and a big part of that evolution is due in part to the Linux How-tos. The Linux
How-tos are a large set of documents that hold the single purpose of enlightening and educating the
general public about Linux and about many of the operating system’s common problems.
The main complaint about many of the How-tos is that they are out of date. The problem with this
system is that a majority of the documents were created as Linux was putting down its roots; hence, there
are a great many references to 1.x kernels or pre-5 releases of many distributions. This datedness of the
material does not mean that it has worn out its welcome. Quite the opposite is true. A vast portion of the
Linux How-tos have stood the test of time and their relevance is still strong.
The Linux How-tos can be found on many Web sites and come in two different types: How-tos and mini
How-tos. The regular How-tos are generally longer, more detailed articles that cover more complex topics
such as:












3Dfx-HOWTO: How to use 3Dfx graphics accelerator chip support
AX25-HOWTO: How to configure AX25 networking for Linux
Access-HOWTO: How to use adaptive technology with Linux
Alpha-HOWTO: Overview of Alpha systems and processors
Assembly-HOWTO: Information on programming in x86 assembly
Bash-Prompt-HOWTO: Creating and controlling terminal and xterm prompts
Belgian-HOWTO: Information on using Linux with Belgian-specific features
Benchmarking-HOWTO: How to do basic benchmarking
Beowulf-HOWTO: Introduces the Beowulf Supercomputer architecture and provides background
information on parallel programming
BootPrompt-HOWTO: List of boot time arguments and overview of booting software
Bootdisk-HOWTO: How to create a boot/root maintenance disk for Linux
Busmouse-HOWTO: Information on bus-mouse compatibility with Linux
The mini How-tos are a group of topics that can be dealt with in a much more expedient fashion. The
range of topics includes:










Three-Button-Mouse: How to configure your mouse to use three buttons
ADSL: Asymmetric Digital Subscriber Loop (ADSL), a new high-speed digital access line
technology
ADSM-Backup: How to install and use the ADSM backup program
AI-Alife: Information about AI software for Linux
Advocacy: Suggestions on how to advocate the use of Linux
Alsa-sound: Describes the installation of the Alsa sound drivers for Linux
Apache+SSL+PHP+fp: How to build a multipurpose Web server
Automount: Describes the autofs automounter, shows how to configure it, and points out some
problems to avoid
Backup-With-MSDOS: How to back up Linux machines with MS-DOS
Battery-Powered: How to reduce a Linux system's power consumption
Often, How-tos and Mini-How-tos can be downloaded for offline browsing and reference.
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The Linux Documentation Project
The Linux Documentation Project (LDP) has become one of the largest documentation projects to date.
The LDP is dedicated solely to documenting the Linux OS, attempting to keep the How-tos up-to-date and
keep the users as informed as possible. The primary feature of this site is its compilation of the various
help systems for Linux. At the LDP, you can read the man pages, How-tos, FAQs, and the Linux Gazette
all in one sitting. The biggest problem with this particular site is its scope. At first glance, the uninitiated
user is overwhelmed by a barrage of text and hyperlinks. This is unfortunate for the new Windows
convert, who is used to buttons and bars. The other drawback to the site is the lack of a search engine.
Regardless of its drawbacks, the LDP is a massive undertaking that acts as the single largest repository
of Linux information.
Other help systems
As with any computer technology, numerous help systems are available for Linux. There are Web sites,
books, newsgroups, mailing lists, Linux User Groups (known as LUGs), magazines, and software
designed to aid the user. Take your pick of what is right for you. Just be cautious that the information
you’re getting is current and that you aren’t being told to use kernel 2.0.x or any GNOME releases prior to
1.0.41.
Conclusion
This primer was meant to be an introduction to the Linux OS. Although there is much more to know, you
should now have a foundation of knowledge about Linux.
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Related TechRepublic resources:
TechRepublic books and CDs:
Quick Reference: Linux Commands
Quick Guide: Network Security Policy
Quick Guide: Network Auditing
Downloads:
Point & Click Linux!: Dipping a toe into the command-line waters
Make Linux act like DOS with these shell scripts
Linux Commands
Articles and columns:
Ready for prime time: Linux is now hassle-free and enterprise-ready
Tech Tip: Set up RAID in Linux with mdadm
Evaluate a switch to Linux with these resources
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