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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?
因此要取得一些重要问题的答案
该发行版能够在今后5年内继续存在吗？
该发行版会持续有更新的安全补丁吗？
该发行版会迅速发布更新软件吗？
如果我有问题，发行商会搭理我吗？
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.
有了这样的认识再来看，有些更有意思、规模更小的发行版本就不太有吸引力了。但是也别把它们排除在外：例如E*Trade就运行在Gentoo Linux上。
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.
最有生命力的发行版本并不一定是最商业化的发行版本。例如，我们认为Debian在相当长的一段时间里是会存在的，尽管Debian并不是一家公司，既不销售任何东西，也不正式提供需要的支持。Debian本身并不是一种广泛使用的发行版本，但是它利益于有一个坚定的贡献群体，也得益于Ubuntu这个基于Debian的发行版本的盛行。
1.5 EXAMPLE SYSTEMS USED IN THIS BOOK
1.5 本书使用的示例系统
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.
我们已经选择了3款Linux发行版本和3款UNIX变体，把它们作为我们全书讨论所采用的示例系统：Ubuntu Linux, openSUSE, Red Hat Enterprise Linux, Solaris, HP-UX, and AIX。这些系统是整个市场的代表，它们加起来占据了现如今投入使用的系统的绝大多数。
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:
除非指定一种特定发行版本，否则本书中的内容一般适用于我们用作示例的所有发行版本。只适用于某种特定发行版本的细节将采用发行商的徽标来标记：
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.
这些徽标的使用已经分别得到其拥有者的善意许可。不过，这些厂商没有复查或者提供本书的内容。下面的段落对每种示例系统稍加说明。
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 用作示例的Linux发行版本
针对Linux而不是任何特定发行版本的知识，左边用Tux企鹅徽标表示。
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的发行版本都保持着支持Linux社群开发和开放访问的思想意识，所以它不存在任何有关自身哪部分*、哪部分可以重新发布的问题。Ubuntu目前还在享受着南非企业家Mark Shuttleworth 的慈善资助。
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基于Debian这个发行版本，使用Debian的软件打包系统。它发展成两种形式；桌面版本；服务器版本。两个版本实际上是类似的，但是服务器版本的内核针对服务器的使用预先做了调配，它不能安装GUI，或者像OpenOffice这样的GUI应用软件。
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现在属于Novell公司，已经走上了和Red Hat一样的路子，分成两种相关的发行版本；一种叫做openSUSE，只包含*软件；另一种叫做SUSE Linux Enterprise，需要花钱购买，包含正规的支持渠道，并且提供了一些额外的东西。本书的内容不专门针对哪一种SUSE的发行版本，所以我们直接把它们都统称为“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.
在过去将近10年的时间里，Red Hat公司一直是Linux业界主导力量，它的发行版在北美地区得到广泛使用。2003年，Red Hat Linux发行版本分成了两种，一种是以生产应用为中心的产品线，叫做Red Hat Enterprise Linux(我们在本书里称为RHEL或者Red Hat)，另一种是依托Linux社群的开发项目，叫做Fedora。在技术、经济、后勤和法律等诸多因素的综合作用下，才促成这次分裂。
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.
这两种发行版本一开始曾经比较相似，但是Fedora在过去5年里做出了一些重大改变，这两种系统现在不再以任何有意思的方式保持同步了，RHEL提供大量支持，而且稳定性好，但是如果不向R ed Hat公司支付许可证费，则无法有效地使用它。
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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.
CentOS项目（centos.org）收集了Red Hat为遵守各种许可证协议（最知名的就是GNU的GPL许可证）而必须公布的源代码，把这些源代码整理成一个类似于RHEL但却免费的完整发行版本。这个发行版本没有Red Hat商标，也没有个别的一些专有工具，但是其他各方面都和RHEL等同。CentOS追求同RHEL在二进制乃至bug上面的完全兼容。
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.
对于那些想要部署一个面向生产应用的发行版本，但又不想向Red Hat公司交钱的个人或企业来说，CentOS是一种很好的选择。采用混合搭配的方式也可行；前端服务器运行Red Hat Enterprise Linux，使之获得Red Hat公司良好的支持，而桌面则运行CentOS。这样的安排既照顾到让重要的基础系统获得安全保障和技术支持，又将成本和系统管理的复杂度降至最低。
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 用作示例的UNIX发行版本
Solaris是System V的一种变体，它从Sun公司获得了许多扩展，Sun公司以前很有名，现在则是Oracle公司的一部分。Sun UNIX（在20世纪80年代中期Solaris就曾叫这个名字）最早源于Berkeley UNIX，但是Sun和AT&T之间的合作伙伴关系（现在这种关系已经成为了历史）导致其代码基础发生了变化。Solaris在Sun公司的手中可以*下载和使用，其中最著名的要数Intel x86和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在Sun公司的手中可以*下载和使用。但是Oracle改变了这项政策，现在下载的Solaris被标为90天免费试用版，OpenSolaris作为一种明确说明是Solaris的开源版本，它的出现又让情况复杂化了。此刻（2010年中期），Oracle对Solaris和OpenSolaris的确规划沿不明朗。
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.
预计在今年的某个时刻发布Solaris 11，迄今为止的种种迹象表明，它会和OpenSolaris很相近。本书中我们称为“Solaris”的是一种混合系统，它基于产品级的Solaris 10和OpenSolaris的发布版，并根据我们在Oracle内的“卧底”提供的指导做了调整。在不多的几个地方，我们会指出Solaris 10 还是 OpenSolaris。