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Some important questions to ask are

Is this distribution going to be around in five years?

Is this distribution going to stay on top of the latest security patches?

Is this distribution going to release updated software promptly?

If I have problems, will the vendor talk to me?

So it's necessary to get answers to some important questions.

Can this release continue to exist for the next five years?

Will there continue to be updated security patches for this release?

Will the release release the updated software quickly?

If I have any questions, will the issuer talk to me?

Viewed in this light, some of the more interesting, offbeat distributions don't

Sound quite so appealing. But don't count them out: E*Trade, for example, runs on Gentoo Linux.

With this understanding, some of the more interesting and smaller distributions are less attractive. But don't rule them out: E*Trade, for example, runs on Gentoo Linux.

The most viable distributions are not necessarily the most corporate. For example

We expect Debian Linux (OK, OK, Debian GNU/Linux!) To remain viable for a long time despite the fact that Debian is not a company, doesn't sell anything, and offers no formal, on-demand support. Debian itself isn't one of the most widely used distributions, but it benefits from a committed group of contributors and from the enormous popularity of the Ubuntu distribution, which is based on it.

The most viable distributions are not necessarily the most commercial distributions. For example, we think that Debian will exist for quite a long time, although Debian is not a company that neither sells anything nor formally provides the support needed. Debian itself is not a widely used distribution, but it benefits from a strong contributor community and the popularity of Ubuntu, a Debian-based distribution.

1.5 EXAMPLE SYSTEMS USED IN THIS BOOK

1.5 sample system used in this book

We have chosen three popular Linux distributions and three UNIX variants as our examples to discuss throughout this book: Ubuntu Linux, openSUSE, Red Hat Enterprise Linux, Solaris, HP-UX, and AIX. These systems are representative of the overall marketplace and account collectively for an overwhelming majority of the installations in use at large sites today.

We have selected 3 Linux distributions and 3 UNIX variants as sample systems for our book discussion: Ubuntu Linux, openSUSE, Red Hat Enterprise Linux, Solaris, HP-UX, and AIX. These systems represent the entire market, and together they account for the vast majority of the systems in use today.

Information in this book generally applies to all of our example systems unless a specific attribution is given. Details particular to one system are marked with the vendor's logo:

Unless a specific distribution is specified, the content in this book generally applies to all distributions that we use as examples. Details that apply only to a particular release will be marked with the publisher's logo:

These logos are used with the kind permission of their respective owners. However, the vendors have not reviewed or endorsed the contents of this book. The paragraphs below provide a bit more detail about each of these example systems.

The use of these logos has been approved in good faith by their owners. However, these manufacturers did not review or provide the contents of this book. The following paragraphs provide a brief description of each example system.

1.5.1 Example Linux distributions

Information that's specific to Linux but not to any particular distribution is marked with the Tux penguin logo shown at left.

1.5.1 Linux distribution used as a sample

Knowledge of Linux rather than any particular distribution is represented on the left by the Tux penguin logo.

The Ubuntu distributions maintain an ideological commitment to community development and open access, so there's never any question about which parts of the distribution are free or redistributable. Ubuntu currently enjoys philanthropic funding from South African entrepreneur Mark Shuttleworth.

Ubuntu distributions maintain the ideology of supporting Linux community development and open access, so it doesn't have any questions about which parts of itself are free and which parts can be rereleased. Ubuntu is still enjoying charitable funding from South African entrepreneur Mark Shuttleworth.

Ubuntu is based on the Debian distribution and uses Debian's packaging system. It comes in two main forms, a Desktop Edition and a Server Edition. They are essentially similar, but the Server Edition kernel comes pretuned for server use and does not install a GUI or GUI applications such as OpenOffice.

Ubuntu is based on the Debian distribution and uses Debian's software packaging system. It has evolved into two forms: the desktop version and the server version. The two versions are actually similar, but the server version of the kernel is pre-provisioned for server use, and it cannot install GUI or GUI applications like OpenOffice.

SUSE, now part of Novell, has taken the path of Red Hat and forked into two related distributions: one (openSUSE) that contains only free software; and another (SUSE Linux Enterprise) that costs money, includes a formal support path, and offers a few extra trinkets. Nothing in this book is specific to one SUSE distribution or the other, so we simply refer to them collectively as "SUSE."

SUSE, which now belongs to Novell, has taken the same path as Red Hat, with two related distributions; one is called openSUSE, which contains only free software, and the other is called SUSE Linux Enterprise, which costs money, includes formal support channels, and provides some extra things. The content of this book is not specific to which SUSE distribution, so we directly refer to them all as "SUSE".

Red Hat has been a dominant force in the Linux world for most of the last decade, and its distributions are widely used in North America. In 2003, the original Red Hat Linux distribution was split into a production-centered line called Red Hat Enterprise Linux (which we refer to as RHEL or Red Hat in this book) and a community-based development project called Fedora. The split was motivated by a variety of technical, economic, logistic, and legal reasons.

For nearly 10 years, Red Hat has been the leading force in the Linux industry, and its distribution has been widely used in North America. In 2003, Red Hat Linux distributions were divided into two types, one is a production application-centric product line called Red Hat Enterprise Linux (we call it RHEL or Red Hat in this book), and the other is a development project based on the Linux community called Fedora. It was only under the combined effect of many factors, such as technology, economy, logistics and law, that this split was brought about.

The distributions were initially similar, but Fedora has made some significant changes over the last five years and the two systems aren't currently synchronized in any meaningful way. RHEL offers great support and stability but is effectively impossible to use without paying licensing fees to Red Hat.

The two distributions were similar at first, but Fedora has made some major changes in the past five years, and the two systems are no longer in sync in any interesting way. RHEL provides a lot of support and is stable, but you can't use it effectively without paying a license fee to R ed Hat.

August 18, 2016 17:00-17:38

The CentOS Project (centos.org) collects source code that Red Hat is obliged to release under various licensing agreements (most notably, the GNU Public License) and assembles it into a complete distribution that is eerily similar to Red Hat Enterprise Linux, but free of charge. The distribution lacks Red Hat's branding and a few proprietary tools, but is in other respects equivalent. CentOS aspires to full binary and bug-for-bug compatibility with RHEL.

The CentOS project (centos.org) collects the source code that Red Hat must publish in order to comply with various license agreements, best known as GNU's GPL license, and collates the source code into a complete distribution similar to RHEL but free of charge. This distribution has no Red Hat trademark and no individual proprietary tools, but everything else is equivalent to RHEL. CentOS pursues full compatibility with RHEL in binary and even bug.

CentOS is an excellent choice for sites that want to deploy a production-oriented

Distribution without paying tithes to Red Hat. A hybrid approach is also feasible:

Front-line servers can run Red Hat Enterprise Linux and avail themselves of Red Hat's excellent support, while desktops run CentOS. This arrangement covers the important bases in terms of risk and support while also minimizing cost and administrative complexity.

CentOS is a good choice for individuals or enterprises who want to deploy a distribution for production applications but do not want to pay Red Hat. A mix-and-match approach is also possible; the front-end server runs Red Hat Enterprise Linux to make it well supported by Red Hat, while the desktop runs CentOS. This arrangement not only takes into account the security and technical support of important basic systems, but also minimizes the cost and complexity of system management.

1.5.2 Example UNIX distributions

Solaris is a System V derivative with many extensions from the company formerly known as Sun Microsystems, now part of Oracle. Sun UNIX (as it was called in the mid-80s) was originally the progeny of Berkeley UNIX, but a (now historic) corporate partnership between Sun and AT&T forced a change of code base. Solaris runs on a variety of hardware platforms, most notably Intel x86 and SPARC.

1.5.2 UNIX distribution used as a sample

Solaris is a variant of System V, which has received many extensions from Sun, which used to be famous but is now part of Oracle. Sun UNIX (as Solaris called it in the mid-1980s) originated from Berkeley UNIX, but the partnership between Sun and AT&T (which is now a thing of the past) has led to a change in its code base. Solaris is freely available for download and use in the hands of Sun, the most famous of which are Intel x86 and SPARC.

In Sun's hands, Solaris was free to download and use. However, Oracle has changed this policy, and current downloads are labeled as 90-day free trial editions. The existence of OpenSolaris, an explicitly free and open source version of Solaris, complicates the picture as well. At this point (mid-2010), Oracle's exact plans for Solaris and OpenSolaris remain unclear.

Solaris can be downloaded and used freely in the hands of Sun. But Oracle changed this policy, and now the downloaded Solaris is marked as a 90-day free trial, and the emergence of OpenSolaris, as an open source version of Solaris, complicates the situation. At the moment (mid-2010), Oracle's plans for Solaris and OpenSolaris are indeed uncertain.

The release of Solaris 11 is expected some time this year, and every indication so far is that it will hew closely to OpenSolaris. In this book, the composite system we refer to as "Solaris" is based on production Solaris 10 and OpenSolaris releases, adjusted with guidance from our network of deep-cover spies within Oracle. In a few cases, we note specifics for Solaris 10 or OpenSolaris.

Solaris 11 is expected to be released sometime this year, and there are signs so far that it will be very similar to OpenSolaris. What we call "Solaris" in this book is a hybrid system based on the release of product-level Solaris 10 and OpenSolaris, and adjusted according to the guidance provided by our "undercover" in Oracle. In a few places, we will point to Solaris 10 or OpenSolaris.

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