Anatomy of a linuxsystem

1. ANATOMY OF A LINUX SYSTEM
Linux® is named after Linus Torvalds, The Big Ideas Behind Linux Magazines Hardware/Systems ApacheCon: www.apachecon.com Project Hosting
architect of the Linux kernel, the heart of Eric S. Raymond’s The Open Magazine: www.openmagazine.net Storm Linux™ from Stormix Technologies, Inc.: VA Linux Systems: www.valinux.com YAPC (Yet Another Perl Conference): www.collab.net
The cutting edge Linux Magazine: www.linux-mag.com www.stormix.com Penguin Computing: www.yapc.org/America or www.sourceforge.net
the operating system. But a complete Cathedral & The Bazaar www.penguincomputing.com
of open source software Linux Journal: www.linuxjournal.com OpenLinux™ from Caldera Systems: www.yapc.org/Europe Downloads
Linux distribution contains the work of hun- outlines the way a distributed LinuxWorld: www.linuxworld.com www.caldera.com IBM: www.ibm.com/linux www.ibiblio.org
will belong to people who start Cobalt Networks, Inc.: www.cobalt.com Top Linux Web Sites
dreds of separate open source software network of programmers Maximum Linux: www.maximumlinux.com TurboLinux ®: www.turbolinux.com www.linux.com
www.freshmeat.net
from individual vision and brilliance, projects. A surprise to many people is the can build leading-edge, LinuxPPC: www.linuxppc.com Conferences www.themes.org
Major Linux Distributors www.linux.org
www.rpmfind.net/linux/RPM
then amplify it through the effective amount of code that companies like Sun, high-quality software without Red Hat ®: www.redhat.com Yellow Dog Linux™: www.yellowdoglinux.com O’Reilly Open Source Convention: www.slashdot.org
Debian GNU/Linux: www.debian.org Hard Hat™ Linux for Embedded Systems from conferences.oreilly.com www.linuxtoday.com Kernel (News and Notes)
construction of vo l u n t a r y SGI, and Digital (Compaq) have con- centralized control. Another LinuxWorld New York: www.lwn.net www.kernel.org
SuSE: www.suse.com MontaVista Software, Inc.: www.mvista.com
communities of interest. tributed. This poster peels back the skin of O’Reilly book, Open Sources, RTLinux™ from FSMLabs: www.fsmlabs.com www.linuxworldexpo.com www.linuxgazette.com www.kernelnotes.org
Linux-Mandrake™: LinuxWorld San Jose:
—ERIC S. RAYMOND the Linux distribution to show many of the contains essays on open source software www.linux-mandrake.com or www.rtlinux.org O’Reilly Sites Philosophy
The Cathedral & The Bazaar
www.linuxworldexpo.com www.oreilly.com www.fsf.org
major projects and their relationship to each development methodology by many of the key Slackware® Linux: www.slackware.com Atlanta Linux Showcase: www.oreillynet.com www.opensource.org
other and to the whole Linux anatomy. developers who have made it happen. ww.linuxshowcase.com linux.oreilly.com www.opencontent.org
C/C++ Programming Tools Unix Command-Line Utilities Mozilla The X Window System GNOME KDE Office Applications Peer-to-Peer Communication
The FSF’s gcc C compiler is the single Linux includes a full complement of Mozilla, the free version of Netscape’s The X Window System, developed at MIT by Jim Gettys, Bob Scheifler, and a Miguel de Icaza’s GNOME (GNU Object Model Environment) is one of the The K Desktop Environment (KDE) was the first comprehensive graphical Sun’s StarOffice and Corel’s Increasingly, instant messaging and
most important programming tool for Unix command-line tools, courtesy of web browser suite, is the one third- host of contributors, is the foundation of all the Linux graphical user interface most popular graphical desktop environments for Linux. Next-generation inter- environment for Linux, and is still one of the most popular. KDE is built on top WordPerfect Office Suite are the most other peer-to-peer technologies are
Linux, since it is required for building the Free Software Foundation’s GNU party graphical application certain tools. The Linux version of X is maintained by the XFree86 project under the faces based on GNOME are now being developed by companies such as Helix of the Qt™ Toolkit, which is now available under the Q Public License (or QPL). popular third-party office-type applica- looking to be the foundation of the next
the system and all the other tools. project. What many people don’t real- to be on every Linux system. Though leadership of Dirk Hohndel of SuSE. High-level programming toolkits for X Code and Eazel. GNOME includes a choice of window managers, including Qt is a product of Norway’s Trolltech AS and is the foundation of the KDE desk- tions for Linux. They aren’t strictly a revolution in Internet technologies.
Other key tools include make, source ize is that the free implementations of some people argue that Mozilla hasn’t include GTK+, Qt, and Motif (which has recently been released as
™
Enlightenment, Sawfish, and WM, plus facilities for creating applications with top. KDE is the preferred environment on SuSE, Mandrake, and Corel Linux. part of Linux but are bundled with Gnutella and Freenet are peer-to-peer
code control tools like CVS and RCS, many of these tools were developed succeeded as an open source project, OpenMotif®). drag-and-drop support, pull-down menus, and other GUI features. GTK (The Like GNOME, the KDE Group has developed a suite of office applications many distributions or available for file-sharing tools. Jabber® is an open
and editors like vi and Emacs. There as part of Berkeley Unix and con- we believe its contributions are GIMP Toolkit) is the foundation for the GNOME programming language. called KOffice, which includes a word processor and programs for creating pre- download over the Internet. The source instant messaging system with
are many variations of vi, including tributed to the GNU project from immense and will become more Useful Books: Key Web Sites: GNU/GNOME is the default desktop environment for the Red Hat® and Debian sentations, spreadsheets, illustrations, and much more. GNOME team is currently developing a client-server architecture that allows
vim, nvi, elvis, and vile. Along with the there, so the rivalry between Linux pervasive in the future. In addition Volume 8: X Window System www.xfree86.org Linux distributions. Gnumeric, an Excel-like XML-based people to communicate with one
C compiler, all systems need and rely and BSD is overshadowed by deeper to the browser, the Mozilla project is Administrator’s Guide www.x.org spreadsheet application, and another over different IM systems,
on various libraries, including glibc cooperation. responsible for the JavaScript lan- Linda Mui, Eric Pearce www.opengroup.org/openmotif Useful Books: Key Web Sites: Useful Book: Key Web Sites: Evolution, an Outlook Express-type including AOL’s Instant Messenger SM
and libstdc++. guage, Bugzilla, and Tinderbox. Parts Linux X User’s Guide Learning Red Hat Linux www.gnome.org KDE Application Development www.kde.org groupware suite. The GNOME and (AIM) and ICQ.
The bash shell is the most widely used developer.gnome.org
of Mozilla, including Gecko, are being Ellen Siever Bill McCarty Uwe Thiem (MTP) developer.kde.org KDE groups are also developing office
Useful Books: command line shell for Linux. There www.gtk.org
incorporated into other applications Programming with Qt Learning Debian GNU/Linux www.konqueror.org application suites that will include word Useful Book:
are other versions of the classic www.pango.org
Programming with GNU Software and also into the GNOME 2.0 desktop. Matthias Kalle Dalheimer Bill McCarty koffice.kde.org processors, presentation software, Peer-to-Peer: The Disruptive Potential
Bourne shell, along with tcsh, a www.helixcode.com
Mike Loukides, Andy Oram GTK+/Gnome Application Development www.trolltech.com and image editing/viewing tools. Other
modern version of the C Shell (csh). Key Web Sites: The Concise Guide to www.eazel.com Behind Collaborative Networking
Learning the vi Editor Havoc Pennington (New Riders) www.trolltech.com/qpl companies, including ApplixWare and
www.mozilla.org XFree86 for Linux Gene Kan, Jeremie Miller
Linda Lamb, Arnold Robbins Useful Books: Aron Hsiao (Que) AbiSource, are also developing office
www.mozillazine.org (forthcoming from O’Reilly)
CVS Pocket Reference Linux in a Nutshell applications for Linux for commercial
Gregor N. Purdy Ellen Siever, Stephen Spainhour, distribution. The GIMP (GNU Image
Manipulation Program) is an open Key Web Sites:
Learning GNU Emacs Jessica Hekman, Stephen Figgins
source Photoshop® clone, and www.jabber.org (developers)
Debra Cameron, Bill Rosenblatt, Running Linux
Ghostscript is a freely available www.jabber.com (users)
Eric S. Raymond Matt Welsh, Matthias Kalle Dalheimer,
PostScript interpreter. gnutella.wego.com
GNU Emacs Manual Lar Kaufman
freenet.sourceforge.net
Richard M. Stallman (FSF) sed & awk
Useful Books:
Managing Projects with make Dale Dougherty, Arnold Robbins
Andrew Oram, Steve Talbott GIMP Pocket Reference
sed & awk Pocket Reference
Debugging with GDB:
The GNU Source-Level Debugger
Arnold Robbins
Effective awk Programming
USERS Sven Neumann
Grokking the GIMP
Richard M. Stallman, Cygnus Solutions Arnold Robbins Carey Bunks (New Riders) Databases
(FSF) (forthcoming from O’Reilly)
Learning the bash Shell Key Web Sites: Databases are critical for even small
Cameron Newham, Bill Rosenblatt www.openoffice.org organizations; they store the content for
Using csh & tsch www.corel.com many web sites with interfaces through
Perl, Tcl, and Python koffice.kde.org Perl DBI, PHP, or other languages. The
Paul DuBois
www.abisource.com Berkeley DB, originally developed and
Scripting languages are widely used Key Web Site: www.vistasource.com maintained by Margo Selzer and Keith
on Linux for everything from system www.fsf.org www.gimp.org Bostic, is now maintained by their com-
administration to generating web pany, Sleepycat Software. The Berkeley
content. Larry Wall’s Perl is the most DB is quite flexible, supporting C, C++,
RS
widely used but John Ousterhout’s Tcl Java, Tcl, Perl, and Python APIs. There
and Guido van Rossum’s Python are Web Server Software are also a variety of SQL-based data-
also extremely popular languages, all base applications available for Linux,
E
included in a typical Linux distribution. Mail Servers and List Managers the most popular of which is MySQL,
Apache is the dominant web server
M
Thousands of Perl modules are avail- developed by Michael Widenius.
not only on Linux but on the Web as
Other database projects include DB2
AM
able from CPAN, the Comprehensive a whole, with more than 60 percent
Perl Archive Network. The Tk toolkit Email is one of the must-have applica- for Linux from IBM, PostgreSQL,
of all visible web servers running tions for any modern system. Users
allows the creation of graphical appli- and mSQL.
Apache. Apache was created by the often rely on their ISP to handle the
GR
cations from any of these languages. Apache Group and is now maintained
ActiveState is developing a new IDE gory details of mail forwarding and Useful Books:
by the Apache Software Foundation. In delivery, but many administrators need
for Perl and Python called Komodo, addition to the core Apache server MySQL & mSQL
which is based on Mozilla. to set up these services themselves.
project, there are projects for Perl on Randy Jay Yarger, George Reese,
PRO
Eric Allman’s sendmail,® developed
Apache, Java Server Pages (Jakarta) in 1979 as part of Berkeley’s Unix, is Tim King
Useful Books: and XML. mod_perl, mod_serv, and the granddaddy of Internet mail servers MySQL
Programming Perl PHP are widely used for generating
Larry Wall, Tom Christiansen, and still the most widely used, but Paul DuBois (New Riders)
dynamic content on Apache servers. Linux also includes Dan Bernstein’s
Jon Orwant Developers in the Apache GUI project Mastering PostgreSQL
qmail and University of Cambridge’s Stephen J. Lombardo
Learning Perl are working on a cross-platform graph- Exim.
TRATO S
Randal L. Schwartz, Tom Christiansen ical tool called Comanche (which (forthcoming from O’Reilly)
Perl Cookbook stands for configuration manager for
R
One of the earliest forms of peer-to-
Tom Christiansen, Nathan Torkington Apache) to help make Apache easier peer communication over the Internet
Key Web Sites:
Perl in a Nutshell to configure. Zope is the most compre- came in the form of email mailing lists. Berkeley DB: www.sleepycat.com
Ellen Siever, Stephen Spainhour, hensive software for web site design Whether the discussion takes place on www.mysql.com
Nathan Patwardhan and management in the open source an internal server, or in a public forum, www.postgresql.org
Programming the Perl DBI world. Using Python-based tools, it mailing lists bring people with like inter- DB2: www.ibm.com/db2/linux
Alligator Descartes, Tim Bunce combines dynamic content manage- ests together using list management
ment, shared development, and sup- software such as LISTSERV,
Learning Perl/Tk
port for sophisticated management Majordomo, Listproc, SmartList,
Nancy Walsh
techniques like version control and Mailman, and ezmlm.
Object Oriented Perl
NIS
staging.
Damian Conway (Manning)
Security
Tcl and the Tk Toolkit Useful Books:
John K. Ousterhout (Addison-Wesley) Apache: The Definitive Guide
Useful Books:
Linux offers traditional Unix security
MI
Effective Tcl/Tk Programming Ben Laurie, Peter Laurie sendmail
Mark Harrison, Michael McLennan Bryan Costales, Eric Allman plus a sophisticated filtering and
Writing Apache Modules with
(Addison-Wesley) Managing Mailing Lists
network address translation (NAT)
AD
Perl and C
mechanism. In addition, there are
Tcl/Tk in a Nutshell Lincoln Stein, Doug MacEachern Alan Schwartz
dozens of useful network and security
Paul Raines, Jeff Tranter HTML & XHTML: The Definitive Guide Stopping Spam tools in a typical Linux distribution or
Exploring Expect Chuck Musciano, Bill Kennedy
M
Alan Schwartz, Simson Garfinkel downloadable from the net.
Don Libes
Learning Python
JavaScript: The Definitive Guide
David Flanagan
T E Network Analysis: tcpd, tcpdmatch,
YS
Mark Lutz, David Ascher Dynamic HTML: Key Web Sites: tcpdump, traceroute, Hummer, Snort
Programming Python The Definitive Reference www.sendmail.org
Mark Lutz
Python Pocket Reference
Danny Goodman
CGI Programming with Perl
Scott Guelich, Shishir Gundavaram,
S www.sendmail.net
www.sendmail.com
Security Auditing: COPS, ISS,
SATAN, Tripwire
Mark Lutz www.qmail.org
Gunther Birznieks www.exim.org Firewalls: ipfilter, portmap, socks,
Python Essential Reference
Web Design in a Nutshell
wrappers
David M. Beazley (New Riders) www.postfix.org
Jennifer Niederst LISTSERV: www.lsoft.com
Key Web Sites: Encryption Tools: PGP, Kerberos
Majordomo:
www.perl.com Key Web Sites:
www.greatcircle.com/majordomo Remote Access: SSH, Radius
www.cpan.org
www.perl.org
www.apache.org
www.comanche.org WEBM SmartList: www.procmail.org
perl.oreilly.com
www.ajubasolutions.com
xml.apache.org
www.apacheweek.com
AS TER S
Mailman: www.list.org
www.ezmlm.org
Security Management: swatch,
watcher, etc.
www.python.org www.php.net
www.activestate.com www.xml.com Useful Books:
www.masonhq.com www.zope.org Practical Unix & Internet Security
www.pm.org www.w3.org Simson Garfinkel, Gene Spafford
Samba Building Internet Firewalls
Elizabeth D. Zwicky, Simon Cooper,
D. Brent Chapman
TCP/IP and the DNS Kernel and Device Drivers Samba allows the Linux or Unix system
to act as a file and print server on a SSH, The Secure Shell:
Java™ XML and HTML Protocols, Standards, and Data Formats The Definitive Guide
Linus’s kernel is the heart of the Windows® network. It’s a high-profile
Many people don’t realize that Bill Joy Daniel J. Barrett, Richard Silverman
system. The current version is 2.2, application that is helping to drive
and his team at UC Berkeley originally To some, Java and Linux might Useful Books:
and is the same on all distributions, Tim Berners-Lee’s introduction of the to-peer instant messaging system, JavaScript: The Definitive Guide There is a host of standards and Managing IMAP Linux’s acceptance in a corporate Linux ® Firewalls
developed the implementation of the sound like an odd combination, but protocols that we all rely on, and
although the most recent kernel patch, Database Programming HyperText Markup Language (HTML) relies heavily on XML as its transport David Flanagan Dianna Mullet, Kevin Mullet setting. Samba received support from Robert L. Ziegler (New Riders)
TCP/IP stack that forms the foundation in reality, there’s a lot going on in took the Internet by storm in 1993 we often use them without even Australian National University, SGI,
with JDBC and Java language, and XSLT gives developers
All books listed are published by O’Reilly & Associates, Inc., except where noted.
2.2.16, is not. Designing with JavaScript Using & Managing PPP Firewalls and Internet Security
of the Internet, including all commercial this space. Sun has a long-standing when people outside of technical cir- the ability to transform XML documents giving them a thought. Things like and Linuxcare.
George Reese Nick Heinle, Martin Webb Andrew Sun William R. Cheswick, Steven M. Bellovin
versions. The Linux version is derived link to Linux, supplying developers cles realized its potential for spread- into output forms such as PostScript, TCP/IP and Ethernet for network
Useful Books: Java in a Nutshell Java and XML Internet Core Protocols: (Addison-Wesley)
directly from the BSD code. BIND, the and source code for the kernel, in ing information over the then-fledgling PDF, ASCII text, and HTML. communication and data transmis-
Running Linux David Flanagan Brett McLaughlin The Definitive Guide
server that implements the domain addition to their recent contribution World Wide Web (WWW). In the sion; DHCP for doling out IP Useful Books: Applied Cryptography
Matt Welsh, Matthias Kalle Dalheimer, Jini in a Nutshell Web Design in a Nutshell Eric Hall
name system, was designed by Paul to the community by GPLing years since, the HTML standard has addresses within a host network; Bruce Schneier (Addison-Wesley)
Lar Kaufman Scott Oaks, Henry Wong Jennifer Niederst Ethernet: The Definitive Guide Using Samba
Mockapetris and built by Paul Vixie, StarOffice. Other Java-Linux con-
™
been through a few iterations, and the Useful Books: SMTP, POP3, and IMAP for send- PGP
Learning Red Hat Linux Java™ Programming on Linux HTML Pocket Reference Charles E. Spurgeon Robert Eckstein, David Collier-Brown,
who still maintains it at the nonprofit nections include the Blackdown Web has evolved into a media-rich HTML & XHTML: The Definitive Guide ing and receiving email; HTTP for Simson Garfinkel
Bill McCarty Nathan Meyers (Waite Group Press) Jennifer Niederst Managing Usenet Peter Kelly
Internet Software Consortium. ISC Project, which is a world-wide environment dominated by things like Chuck Musciano, Bill Kennedy the Web, and FTP for transferring
Learning Debian GNU/Linux Java and XML Henry Spencer Managing NFS and NIS Maximum Linux Security
also maintains INN, the most widely community of volunteer developers the Document Object Model (DOM), JavaScript Pocket Reference files over the Internet; and NNTP
Cascading Style Sheets: Anonymous (SAMS)
used usenet news server software. Bill McCarty who are working to bring the Java Brett McLaughlin David Flanagan for accessing Usenet news. Then PNG: The Definitive Guide Hal Stern
JavaScript, and other advancements The Definitive Guide
Linux Device Drivers platform to Linux, and Kaffe, a like Cascading Style Sheets (CSS). XML Pocket Reference there are MIME-types for images, Greg Roelofs
Eric A. Meyer
Useful Books: Alessandro Rubini cross-platform implementation of But HTML isn’t flexible enough for Robert Eckstein video, audio, and documents. We DocBook: The Definitive Guide Key Web Sites:
Key Web Sites: Dynamic HTML: CERIAS: www.cerias.purdue.edu
Linux Network Administrator’s Guide Linux Multimedia Guide the Java Virtual Machine (JVM). today’s web, and the eXtensible PHP Pocket Reference live and breathe these standards, Norman Walsh, Leonard Muellner Key Web Sites:
www.sun.com/linux The Definitive Reference
Olaf Kirch, Terry Dawson Jeff Tranter Founded by Tim Wilkinson, Kaffe Markup Language (XML) was at first Rasmus Lerdorf often without knowing we’re doing MP3: The Definitive Guide Samba Home: www.samba.org CIAC: ciac.llnl.gov
www.blackdown.org Danny Goodman
TCP/IP Network Administration Understanding the Linux Kernel supports Sun’s own Solaris, Linux, deemed to be far ahead of itself. it. Open protocol standards are Scot Hacker Gene Spafford’s Home Page:
www.kaffe.org Programming PHP SWAT: anu.samba.org/cgi-bin/swat
Craig Hunt Daniel P Bovet, Marco Cesati
. Microsoft Windows® and Windows That’s changed. The new version of Key Web Sites: a key part of what makes the HTTP Pocket Reference www.cerias.purdue.edu/homes/spaf
CE, and even DOS, and is finding jakarta.apache.org Rasmus Lerdorf, Randy Jay Yarger, www.xml.com KSamba: security.oreilly.com
DNS and BIND Building Linux Clusters HTML, XHTML, builds upon its exist- Internet work. Clinton Wong
a new home in embedded systems. www.openoffice.org Andi Gutmans, Zeev Suraski, www.ibm.com/developer/sml www.kneschke.de/projekte/ksamba
Paul Albitz, Cricket Liu David HM Spector ing structure by adding some of www.linuxsecurity.com
Stig Bakken, Shane Caraveo www.w3.org Useful Books: GnoSamba:
Other Java-related open source XML’s powerful features. XML is Key Web Sites: www.first.org
Managing Usenet Linux Application Development Web Application Development
projects include Java Server Pages quickly becoming the defacto markup www.webstandards.org TCP/IP Network Administration www.ietf.org www.open-systems.com/ www.alw.nih.gov/Security
Henry Spencer, David Lawrence Michael K. Johnson, Eric W. Troan with PHP 4.0
(JSP/Jakarta), and Enhydra (a for transporting all kinds of data over www.irt.org Craig Hunt www.ieee.org gnosamba.html
(Addison-Wesley) Tobias Ratschiller, Till Gerken www.rootshell.org
Java/ XML-based application server the Internet and between applica- www.jabber.org Managing IP Networks with www.openldap.org
Key Web Sites: (New Riders) www.securityfocus.com
Key Web Site: and development environment). tions. Jabber, an open source, peer- www.php.net Cisco Routers
www.isc.org www.freeswan.org
www.ietf.org www.kernel.org Scott M. Ballew
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KEY CONTRIBUTORS: glibc: Roland McGrath, Ulrich Drepper GNOME: Miguel de Icaza Perl: Larry Wall, Chip Salzenburg, Qmail: Dan Bernstein Created by Tim O’Reilly and Chuck Toporek Designed by Kathryn Heflin and COPYRIGHT © 2001
Linux Kernel: Linus Torvalds, Alan Cox GNU tools (Emacs and vision of the KDE: Matthias Ettrich, Torben Weis Tom Christiansen, Tim Bunce, sendmail: Eric Allman with review and input from Andy Oram, David Bacigalupi with input from