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Interview with Mark G. Sobell

Author of A Practical Guide to Red Hat Linux, Second Edition

For this issue, I'm going to talk with long-time Linux author Mark Sobell. Mark's first Linux book came out in 1996, when Linux was in its infancy. In this interview Mark discusses Red Hat's Fedora Core 2 version of Linux and his experiences writing Linux books.

LWM: I know you've written a lot of books. When did you write your first one?
My first book, A Practical Guide to the UNIX System, was published in 1982. At that time it was one of three or four books on UNIX. Since then, I've written a number of books on System V and BSD UNIX, databases, Solaris, and three books on Linux.

LWM: How does A Practical Guide to Red Hat Linux, Second Edition differ from the previous edition?
Good question. We've come a long way since 1982. Today, technical bookstores have whole sections dedicated to UNIX and Linux. The audience has matured and I've tried to keep up. The most significant change is that today many readers want to set up servers on Linux. For those readers, I spent last winter writing chapters covering Apache, Samba, DNS/BIND, OpenSSH, NIS, sendmail, FTP (vsftpd), OpenSSH (ssh, scp, and sftp), and NFS. Because security is such a big issue, I also added a chapter on iptables so that readers would be able to set up firewalls to protect their servers.

Another important difference is that the first edition had two CDs, and they were Publisher's Edition CDs. I don't know if your readers are aware, but Red Hat sells publishers CD masters for inclusion in books and these CDs don't have everything that is available when you download Red Hat's ISO image files. With Fedora Core 2, Red Hat has gone to four CDs, so if you go to and download the ISO image files, you end up with four files that you can burn four CDs from. My publisher, Prentice Hall, has been good enough to allow me to include these four CDs, straight from, in the book. I think my book is the only one with these CDs.

Also, this is the first time I've covered two operating systems in one book. Although they are very similar, my book points out the differences between Fedora Core 2 and Red Hat Enterprise Linux. In addition, I've added two chapters that cover the installation of both operating systems.

LWM: Can you please explain to our readers what differentiates Fedora Core from Red Hat Enterprise Linux?
Fedora is free, as in free beer, and you have to pay for Red Hat Enterprise Linux. Red Hat Enterprise Linux is a stable release that's intended for corporate customers who are willing to trade bleeding-edge technology for stability and longevity. Fedora is Red Hat's test bed. A new version is released about every six months with all the latest software and features. For example, Fedora includes the Linux 2.6 kernel, while Red Hat Enterprise Linux uses a 2.4 kernel. Similarly, Fedora includes Samba 3, while Red Hat Enterprise Linux uses Samba 2. I imagine that the next release of Red Hat Enterprise Linux will include the 2.6 kernel and Samba 3.

LWM: What about the battle between the command-line interface and the graphical interface? Which one is better?
That's really a matter of preference. Someone using Linux in an office will probably want to use the KDE or GNOME graphical interface because that is what they are used to and it's easier to use in most cases. The real question is what does a system administrator use? Red Hat has been improving its GUI system administrator tools. By the way, in Fedora Core 2, the names of the tools have all been changed from redhat-config-* to system-config-*; same tools, different names. As I said, these tools are getting pretty good. Personally, I prefer to use vi and edit the various files by hand. Although I cover the graphical system administration tools in the book, I do go into quite a bit of detail about the files and how to configure the system and servers using the configuration files.

LWM: What is one of the most interesting things you learned while writing this book?
That's hard; I learned a lot. I like writing books for the same reasons I like teaching. Both force you to dig into the material and understand it to a depth not required if you are just using it. The two things that stand out in my mind are DNS/BIND and OpenSSH. I never realized how distributed the DNS database is, nor how the domain for reverse-name resolution actually works. Although I have used ssh for quite a while, I didn't realize how simply elegant it is and how it uses the various keys to authenticate systems and ensure the privacy of data transmitted over the Internet.

LWM: Is there anything else you'd like to say to our readers?
It has been said a million times before, but "Have fun!" There is so much going on in Linux today, so many new tools and features, that you cannot help but find something you would like to use, create, or improve. I've just started using gphoto2, which comes with Red Hat Linux, to download and store my digital photographs. Just browse through the Main menu to find all sorts of graphical, audio, and Internet tools. And don't forget about the Linux games. You can search on "Linux games" or just go to for a pretty complete collection.

Mark G. Sobell is president of Sobell Associates Inc., a consulting firm that specializes in UNIX/Linux training, support, and custom software development. He is the author of many best-selling UNIX and Linux books and has more than 25 years of experience working with UNIX and Linux. His most recent book is A Practical Guide to Red Hat Linux, Second Edition: Fedora Core and Red Hat Enterprise Linux, published by Prentice Hall. Go to for more information on Mark Sobell's books.

More Stories By Ibrahim Haddad

Ibrahim Haddad is a member of the management team at The Linux Foundation responsible for technical, legal and compliance projects and initiatives. Prior to that, he ran the Open Source Office at Palm, the Open Source Technology Group at Motorola, and Global Telecommunications Initiatives at The Open Source Development Labs. Ibrahim started his career as a member of the research team at Ericsson Research focusing on advanced research for system architecture of 3G wireless IP networks and on the adoption of open source software in telecom. Ibrahim graduated from Concordia University (Montréal, Canada) with a Ph.D. in Computer Science. He is a Contributing Editor to the Linux Journal. Ibrahim is fluent in Arabic, English and French. He can be reached via

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