UnixWorld Online: Tutorial Article No. 004 Getting Acquainted with Linux

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UnixWorld Online: Tutorial Article No. 004 Getting Acquainted with Linux

By Richard Reich

[ Editor's Note: This article has been re-checked and updated by the author, and the new version made available: 10 Nov 96].

Visionaries predict that great collaborative projects will flow from the global Internet. But PC users disposed to prefer Unix over Microsoft operating systems are already familiar with one example of successful international cooperative work: the Linux operating system. The global Internet plays an on-going, crucial role in the development of Linux. System features are implemented at numerous places by many different people. The system--all of it, complete and up-to-date--is freely available on the Internet, as well as in the form of less timely, but more convenient, CD-ROM distribution packages . Bugs and inadequacies are found and diagnosed rapidly by the global user community, all of whom have access to the source code through the Linux Source Navigator (<URL:http://sunsite.unc.edu/navigator-bin/navigator.cgi?>)

Linux Basics

Linux is a freely-distributed, protected-mode, 32-bit, multitasking Unix-like operating system that runs on Intel 386, 486, and Pentium processors. Recently it's been implemented on other platforms as well, including the DEC Alpha and Power Macintosh. The system is generally considered to be of high quality.

This PC operating system began life as a small program initially written by Linus Torvalds, a student in Helsinki, Finland, with subsequent contributions by many others. Linus remains the integrator of all changes and additions to the Linux kernel, the main operating system component that defines its basic facilities. Although there is a core group of major contributors among Linux workers (<URL:http://sunsite.unc.edu/navigator-bin/navigator.cgi?CREDITS>), the open development philosophy adopted by Linus accepts competent work from anyone, anywhere.

Linux also owes its success to the way it is distributed: it's free, but not in the public domain. Initially, Linus prohibited any charges for the system--not even a fee for copying. However, he decided soon after to distribute Linux under the Free Software Foundation's General Public License (GPL) (<URL:ftp://prep.ai.mit.edu/pub/gnu/GPL>).

The GPL places no restrictions on what can be charged for the software, but does require that the source code be made available at a reasonable price and that no additionally restrictive contract can be imposed on subsequent distribution. Source code availability means that bugs will be found and repaired quickly and improvements in features and performance can be initiated by anyone. The GPL, because it permits charging for distribution, has encouraged many companies to offer CD-ROM versions of Linux and the competition among them keeps the CD-ROM distributions up-to-date and of adequate quality. Distributors often attempt to differentiate their products by adding huge amounts of precompiled free software along with the basic Linux programs. Installation packages, though still not absolutely bullet-proof, are also continually improved by the Linux system packagers.

Linux distributions include the GNU programs (<URL:ftp://prep.ai.mit.edu/pub/gnu/>) from the Free Software Foundation (FSF). These give Linux a high quality set of compilers (gcc, g++), libraries and utilities (Emacs, Ghostscript) that facilitate software development. The XFree86 (<URL:http://www.xfree86.org/XFree86/>) implementation of the X Window System provides a standard graphical user interface, but at the cost of bulking up the system in terms of memory and CPU requirements. Also available in a Linux version is the Andrew System (<URL:http://www.cs.cmu.edu/afs/cs.cmu.edu/project/atk-ftp/web/andrew-home.html>) from Carnegie Mellon University, containing among other things, a useful multimedia document editor and a very capable mail user agent. Adding these packages and others to the Linux kernel results in a full-scale, useful operating system. Several versions of Motif are available for Linux, and a few free Motif clones are in varying stages of development.

Linux offers a strong array of standards-based networking support services and tools. The kernel has TCP/IP, LAN, SLIP and PPP protocol implementations, as well as kernel-level hooks for IP acco unting, packet filtering and multicasting. Linux versions of the Unix standards are all available: client and server FTP and Telnet, Domain Name Service (DNS), various routing programs, security and firewall tools, mail transfer agents, mailing list servers, news servers and readers, gopher, WAIS, and World Wide Web servers.

Linux can act as an X workstation, but strong ``productivity tools''--most notably a WYSIWYG word processor--are not generally available for Linux. (LaTeX fans need not worry though--it's available.) There are a few projects underway to address this; they range from a direct implementation of a Linux-based WYSIWYG word processor to a couple of emulation strategies. The list of commercial programs that run under Linux is not vast, though it is growing.

Caldera, Inc. (<URL:http://www.caldera.com>), a Utah startup firm, sells Linux with a desktop user interface and IPX connectivity. They also offer an "office sui te" consisting of Corel's WordPerfect for UNIX, NCD Software's Z-mail e-mail package, XESS Software's NExS Spreadsheet, and Metrolink's Executive Motif Libraries. Caldera has also promised to begin offering Sun's WABI Windows emulation package.

Red Hat, Inc. (<URL:http://www.redhat.com/>) is selling the Applixware suite (<URL:http://www.redhat.com/products/apx.html>) of programs, including a word processor, spreadsheet, and mail client.

Although several broad types of Linux distribution (<URL:http://sunsite.unc.edu/mdw/HOWTO/Distribution-HOWTO.html>) exist, the current popular favorites are the so-called ``Slackware'' and ``Red Hat'' distributions, both available for downloading (<URL:ft p://sunsite.unc.edu/pub/Linux/distributions/>) from Sunsite (University of North Carolina at Chapel Hill) and its mirrors. Easier-to-install commercial versions of Slackware are available on CD-ROM. Red Hat is the basis of the Caldera release as well as being available on CD-ROM from Red Hat, Inc (<URL:http://www.redhat.com/>).

A Few Uses of Linux

Linux is very suitable to run various network servers with limited hardware resources. It's especially popular as a DNS machine, or as a bastion Web or FTP server. Any TCP/IP network application that doesn't need Sun or HP horsepower is a Linux candidate.

With the XFree86 X11/R6 implementation, Linux can run a cheap, but adequate X server. Because of the availability of source code and its unbeatable price, it's a good system for a Unix classroom setting.

In general, if a need can be met with an old 386 or 486 PC, the system to think of is Linux. (L inux shouldn't be thought of exclusively as a poor man's Unix. It can be found in some impressive applications. For example, Lycos, one of the well- known Web indexing-spider sites, uses a couple of Linux machines, among others.)

What's the Whole Story?

Linux is in continual development. The system is generally very solid, but the temptation to upgrade your system to the latest version can be dangerous. Fortunately, many people are eager to run the latest versions of everything and they will provide adequate warning of serious problems to the more wary.

For the time being, support for Linux is entirely on a volunteer basis, just as is its development. (Caldera may change this, but probably at a price.) Most of the Linux CD-ROM distributors have good intentions with regard to support, but the economics of their business does not generate the unit revenue necessary to manage full-blown technical support. It is important to keep the support issue in mind, but al so be aware that the online, Internet-based support of Linux is usually excellent. Linux and its companion programs rarely reach release stage with serious bugs, and most of the exceptions are found and repaired very rapidly. (The benefits of universally available source are demonstrable.) Linux newsgroups are a ready source of help and advice at all levels of expertise.

Linux supports a broad array of hardware (<URL:http://sunsite.unc.edu/mdw/HOWTO/Hardware-HOWTO.html>) and does not require a lot of CPU horsepower for general use, but it never hurts to have it available. Depending on configuration, Linux requires at least 4MB for practical use. Multi-user configurations or development systems will do well with at least 16MB. For a single-user or small network gateway/multi-server setup, 8MB will likely suffice. Disk space requirements are determined by many factors, but 80 to 100 MB is a c omfortable first approximation. A CD-ROM drive, at least during installation, is an obvious requirement if you install from a CD-ROM distribution.

Linux Resources

Books

Welsh, Matt and Lar Kaufman. Running Linux, 2nd Edition (<URL:http://www.ora.com/catalog/runux2/>).
Sebastopol, CA: O'Reilly and Associates, 1996 (ISBN 1-56592-151-8).
Kirch, Olaf. Linux Network Administrator's Guide (<URL:http://www.ora.com/catalog/linag/>).
Sebastopol, CA: O'Reilly and Associates, 1995 (ISBN 1-56592-087-2).
Tackett, Jack et al. Special Edition Using Linux (<URL:http://www.mcp.com/cgi-bin/bag?
isbn=0-7897-0100-6&userID=129566528&last=/books tore>).
Indianapolis, IN: Que/Macmillan, 1992 (0-7897-0100-6).

Magazines and Newsletters

Linux Journal (<URL:http://www.ssc.com/lj/index.html>) is a monthly Linux magazine with a wide range of articles: introductory, technical, business-oriented. Published by SSC, Inc., Seattle, WA.

The Linux Newsletter , a free, emailed publication.

Mailing Lists

The current center of Linux mailing list activity is Majordomo@vger.rutgers.edu . To obtain a list of all lists maintained there, send e-mail with just the word ``lists'' in the body of the message. To subscribe to a list, send e-mail with ``subscribe list-name'' in the body of the message. Here's the current [as of 11 Nov 96] list of available ``vger'' mailing lists:

linux-8086
linux-admin
linux-alpha
linux-apps
linux-arm
linux-bbs
linux-c-programming
linux-config
linux-console
linux-diald
linux-doc
linux-fido
linux-fsf
linux-ftp
linux-gcc
linux-gcc-digest
linux-hams
linux-hppa
linux-ibcs2
linux-ipx
linux-isdn
linux-japanese
linux-kernel
linux-kernel-digest
linux-kernel-patch
linux-laptop
linux-linuxss
linux-lugnuts
linux-mca
linux-mips
linux-msdos
linux-msdos-devel
linux-msdos-digest
linux-net
linux-new-lists
linux-newbie
linux-nys
linux-oasg
linux-oi
linux-opengl
linux-pkg
linux-ppp
linux-pro
linux-qag
linux-raid
linux-scsi
linux-seria l
linux-seyon
linux-smp
linux-sound
linux-standards
linux-svgalib
linux-tape
linux-term
linux-userfs
linux-word
linux-x11

The four Linux security mailing lists:

linux-alert
linux-alert-digest
linux-security
linux-security-digest

have been moved to a mailing list server at Red Hat Software. (Many thanks go out to Marc Ewing at Red Hat for offering his site as a host for these mailing lists, as well as for aiding in the transition.)

The submission addresses for the mailing lists are now:

linux-alert@redhat.com

linux-alert-digest@redhat.com

linux-security@redhat.com

linux-security-digest@redhat.com

Aliases will remain on linux.nrao.edu (a.k.a. tarsier.cv.nrao.edu) for an indefinite period that will forward all posts to the old list submission addresses on to their respective new addresse s at Red Hat.

Because Red Hat is not running a Majordomo mailing-list server, a slightly different mechanism is now in place for subscribing and unsubscribing to and from the security lists. Rather than sending all subscription activity requests to a ``majordomo@'' address with the commands in the message body, the new mechanism is to send the requests to list-name -request@redhat.com with the keyword ``subscribe'' or ``unsubscribe'' in the ``Subject:'' header.

This means that the administrative addresses are now:

linux-alert-request@redhat.com

linux-alert-digest-request@redhat.com

linux-security-request@redhat.com

linux-security-digest-request@redhat.com

Forwarding aliases from list-name -request@linux.nrao.edu to the respective new addresses at Red Hat will also remain on the old server for an indefinite period.

Information regarding the mailing-list archives and their availability will be made available once the new archives at Red Hat are fully on-line and consolidated with the old archives at NRAO.

Some new subscribers may have received a ``Welcome to the blinux-list!'' when their subscription request was processed. This is of course an error, and is being fixed; the subscriptions went to the right lists, but it appears that the wrong list-information file was sent back out. There will undoubtedly be some other small kinks during this transition period.

Newsgroups

The Linux newsgroups are very busy, reflecting a high level of interest. They currently include:

comp.os.linux.advocacy: Benefits of Linux compared to other operating systems.
comp.os.linux.announce: Announcements important to the Linux community. (Moderated)
comp.os.linux.answers: FAQs, How-To's, READMEs, etc. about Linux. (Moderated)
comp.os.linux.development.apps: General Linux applications issues
comp.os.linux.development.system: Linux system programming, porting issues
comp.os.linux.hardware: Hardware compatibility with the Linux operating system.
comp.os.linux.misc: Questions and advice about Linux.
comp.os.linux.networking: Linux networking: TCP/IP, LAN, NFS, Samba, etc.
comp.os.linux.setup: Linux installation and system administration.
comp.os.linux.x: Linux X Window System servers, clients, libs and fonts.

Web Pages

Linux-related Web pages, naturally, are highly cross-referenced through their links. If you begin with a well-connected page, you wil l eventually find them all. However, to save a bit of time, here some major starting points:

The Linux Organization maintains the Linux Home Page (<URL:http://www.linux.org/>), which provides some general information, as well as pointers to lots more. This site is duplicated by SSC, Inc. (next):

SSC, Inc. offers The Linux Home Page (<URL:http://www.ssc.com/linux/>), including general information regarding the Linux operating system, as well as a base at which to find common references and utilities to help you maintain your Linux system. Site includes:

What Is Linux?
Find out more about this freely-distributable implementation of UNIX.
FAQs AND HOWTOs
Frequently Asked Questions, and other useful sources of information.
The Linux Software Map
A searchable index of available software for Linux.
Manual Pages
Finding man pages for Linux commands.
Usenet Newsgroups
Thousands of people share tips, advice, and news every day on these newsgroups.
Where To Get Linux
Want to get started on Linux? These major FTP distribution sites are your best bet for downloading the latest releases.
Linux Documentation Project
The LDP is set out to produce the canonical set of Linux online and printed documentation.
Linux International
A non-profit organization for promoting the use of Linux everywhere.
Linux On The World Wide Web
Still need more Linux information? Have a look at some of the hundreds of Linux sites available on the Web.
Hot Linux News
The very latest news and press releases for Linux.
Linux Gazette
An on-line WWW publication, and a member of the Linux Documentation Project.
Linux Journal
Linux Journal ^TM is the monthly magazine of the Linux community.
The Linux M all , has the largest selection of Linux related products, and assists both Linux consumers and Linux producers connect.
Sunsite's Welcome Page (<URL:ftp://sunsite.unc.edu/pub/Linux/welcome.html>) is the home page of the primary online repository of Linux distributions, source and executable code, and documentation. This site provides an extensive geographically sorted list of mirror sites, which are recommended because Sunsite can be overloaded.

Sunsite's Linux Meta-FAQ (<URL:http://sunsite.unc.edu/mdw/HOWTO/META-FAQ.html>) has this table of contents:

1. Introduction
2. Getting Linux
3. Linux FTP sites
3.1 Linux on BBS's
3.2 Linux on physical media
3.3 AFS
3.4 Commercial networks
3.5 Mailservers and such
4. Linux distributions (a.k.a. ``releases'')
5. Linux mailing-lists
6. Documentation for
various programs
7. More Documentation
8. Keeping track of current releases
9. This Document
10. Legalese

Sunsite's Linux Documentation Project Home Page (<URL:http://sunsite.unc.edu/mdw/linux.html>) contains all of Linux's online documentation.
Sunsite's Linux Source Navigator (<URL:http://sunsite.unc.edu/linux-source/navigator.html>) is Ben Walter's browsable copy of the current Linux kernel source code.
Sunsite's Hardware Compatibility HOWTO (<URL:ftp://sunsite.unc.edu/pub/Linux/mdw/HOWTO/Hardware-HOWTO.html>) is a must-read, although most PC hardware is currently supported.
Sunsite's Linux Distribution HOWTO (<URL:ht tp://sunsite.unc.edu/mdw/HOWTO/Distribution-HOWTO.html>) is a guide to the various Linux distributions, both freely available and commercial.
Sunsite's Linux Installation and Getting Started Page (<URL:http://sunsite.unc.edu/mdw/LDP/gs/gs.html>) written by Matt Welsh is a complete online book, the precursor to Running Linux published by O'Reilly and Associates. (<URL:http://www.ora.com/catalog/runux2/>).
Carnegie Mellon University is home to the Andrew System (<URL:http://www.cs.cmu.edu/afs/cs.cmu.edu/project/atk-ftp/web/andrew-home.html>), a large, powerful, quite pretty X-based collection of tools: a mailer, multimedia editor, and more.
Caldera's Linux Contributors: The CREDITS File (http://www.caldera.com/credits.html>) is an HTML-format list created from the CREDITS file of the Linux 1.2 release. The current raw Linux CREDITS list (<URL:http://sunsite.unc.edu/navigator-bin/navigator.cgi?CREDITS>) is available as part of the Linux Source Navigator at Sunsite.
Yahoo's Linux section (<URL:http://www.yahoo.com/Computers/Operating_Systems/Unix/Linux/>) has pointers to all the standard--as well as some unusual--Linux Web pages.
XFree86 (<URL:http://www.xfree86.org/XFree86/>) is the organization that ports X11 to Intel-based systems, such as Linux.
Minimalist's Linux Page is a r oundup of all the major Linux operating environment resources available online. [added 1 Nov 97 -- Editor]
Woven Goods for Linux has links to documentation, software and search engines for Linux. [added 1 Nov 97 -- Editor]

User Groups

Linux user groups are spreading. The publisher of Linux Journal maintains a list of them (<URL:http://www.ssc.com/lj/Extras/ug/groups.html>). The best way to find one locally is to post a question to comp.os.linux.misc or read this group for awhile.

Sunsite maintains links to Linux-related user groups (<URL:http://sunsite.unc.edu/mdw/lugs.html>), which currently has over 80 entries from all over the world.

Commercial Distributors

Caldera, Inc. (<URL:http://www.caldera.com/>) sells various value-added packages based on Linux.
Red Hat, Inc. (<URL:http://www.redhat.com/>) offers Red Hat Commercial Linux as well as an application suite, Motif and more.
InfoMagic, Inc. (<URL:http://www.infomagic.com/>) offers a six CD-ROM set including Red Hat and Slackware Linux and loads of other goodies (mostly from archive sites). Moo-Tiff, a Linux Motif, is also available.
Walnut Creek CD-ROM (<URL:http://www.cdrom.com/>) is the publisher of the ``Official'' Slackware Linux CD-ROM. The current version of Slackware is a four CD-ROM set containing Slackware version 3.1. This product was put together by Patrick Volkerding, the creator of the Slackware distribution of Linux. The most curre nt distribution is always available for download from their anonymous FTP site (<URL:ftp://ftp.cdrom.com/pub/linux/>).

Consultants

Some among the small army of Linux consultants can be found at the Linux Consultants HOWTO (<URL:http://consult.cyrius.com>) [URL updated 13 Jul 97].

Downloading Linux

Any of the various Linux distributions can be downloaded--with a lot of time and/or bandwidth!--from:

Sunsite (University of North Carolina) (<URL:ftp://sunsite.unc.edu/pub/Linux/distributions/>)

Finnish University and Research Network (FUNET) (<URL:ftp://ftp.funet.fi/pub/Linux/mirrors/>)

Georgia Tech College of Computing (<URL:ftp://ftp.cc.gatech.edu/pub/linux/distributions/>)

In addition to these major sites, many mirror site are available world-wide. See, for example, the list of Sunsite mirrors (<URL:ftp://sunsite.unc.edu/pub/Linux/MIRRORS>).