UNIX/Linux 系統管理技術手冊閱讀（五）

2016.8.17 16:50-17:50

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問題的答案

  該發行版能夠在今后5年內繼續存在嗎？

  該發行版會持續有更新的安全補丁嗎？

  該發行版會迅速發布更新軟件嗎？

  如果我有問題，發行商會搭理我嗎？

  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.

  有了這樣的認識再來看，有些更有意思、規模更小的發行版本就不太有吸引力了。但是也別把它們排除在外：例如E*Trade就運行在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.

  最有生命力的發行版本并不一定是最商業化的發行版本。例如，我們認為Debian在相當長的一段時間里是會存在的，盡管Debian并不是一家公司，既不銷售任何東西，也不正式提供需要的支持。Debian本身并不是一種廣泛使用的發行版本，但是它利益于有一個堅定的貢獻群體，也得益于Ubuntu這個基于Debian的發行版本的盛行。

1.5 EXAMPLE SYSTEMS USED IN THIS BOOK

1.5 本書使用的示例系統

  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.

  我們已經選擇了3款Linux發行版本和3款UNIX變體，把它們作為我們全書討論所采用的示例系統：Ubuntu Linux, openSUSE, Red Hat Enterprise Linux, Solaris, HP-UX, and AIX。這些系統是整個市場的代表，它們加起來占據了現如今投入使用的系統的絕大多數。

  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:

  除非指定一種特定發行版本，否則本書中的內容一般適用于我們用作示例的所有發行版本。只適用于某種特定發行版本的細節將采用發行商的徽標來標記：

  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.

  這些徽標的使用已經分別得到其擁有者的善意許可。不過，這些廠商沒有復查或者提供本書的內容。下面的段落對每種示例系統稍加說明。

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發行版本

  針對Linux而不是任何特定發行版本的知識，左邊用Tux企鵝徽標表示。

  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的發行版本都保持著支持Linux社群開發和開放訪問的思想意識，所以它不存在任何有關自身哪部分自由、哪部分可以重新發布的問題。Ubuntu目前還在享受著南非企業家Mark Shuttleworth 的慈善資助。

  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這個發行版本，使用Debian的軟件打包系統。它發展成兩種形式；桌面版本；服務器版本。兩個版本實際上是類似的，但是服務器版本的內核針對服務器的使用預先做了調配，它不能安裝GUI，或者像OpenOffice這樣的GUI應用軟件。

  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現在屬于Novell公司，已經走上了和Red Hat一樣的路子，分成兩種相關的發行版本；一種叫做openSUSE，只包含自由軟件；另一種叫做SUSE Linux Enterprise，需要花錢購買，包含正規的支持渠道，并且提供了一些額外的東西。本書的內容不專門針對哪一種SUSE的發行版本，所以我們直接把它們都統稱為“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.

  在過去將近10年的時間里，Red Hat公司一直是Linux業界主導力量，它的發行版在北美地區得到廣泛使用。2003年，Red Hat Linux發行版本分成了兩種，一種是以生產應用為中心的產品線，叫做Red Hat Enterprise Linux(我們在本書里稱為RHEL或者Red Hat)，另一種是依托Linux社群的開發項目，叫做Fedora。在技術、經濟、后勤和法律等諸多因素的綜合作用下，才促成這次分裂。

  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.

  這兩種發行版本一開始曾經比較相似，但是Fedora在過去5年里做出了一些重大改變，這兩種系統現在不再以任何有意思的方式保持同步了，RHEL提供大量支持，而且穩定性好，但是如果不向R ed Hat公司支付許可證費，則無法有效地使用它。

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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項目（centos.org）收集了Red Hat為遵守各種許可證協議（最知名的就是GNU的GPL許可證）而必須公布的源代碼，把這些源代碼整理成一個類似于RHEL但卻免費的完整發行版本。這個發行版本沒有Red Hat商標，也沒有個別的一些專有工具，但是其他各方面都和RHEL等同。CentOS追求同RHEL在二進制乃至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.

  對于那些想要部署一個面向生產應用的發行版本，但又不想向Red Hat公司交錢的個人或企業來說，CentOS是一種很好的選擇。采用混合搭配的方式也可行；前端服務器運行Red Hat Enterprise Linux，使之獲得Red Hat公司良好的支持，而桌面則運行CentOS。這樣的安排既照顧到讓重要的基礎系統獲得安全保障和技術支持，又將成本和系統管理的復雜度降至最低。

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發行版本

  Solaris是System V的一種變體，它從Sun公司獲得了許多擴展，Sun公司以前很有名，現在則是Oracle公司的一部分。Sun UNIX（在20世紀80年代中期Solaris就曾叫這個名字）最早源于Berkeley UNIX，但是Sun和AT&T之間的合作伙伴關系（現在這種關系已經成為了歷史）導致其代碼基礎發生了變化。Solaris在Sun公司的手中可以自由下載和使用，其中最著名的要數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公司的手中可以自由下載和使用。但是Oracle改變了這項政策，現在下載的Solaris被標為90天免費試用版，OpenSolaris作為一種明確說明是Solaris的開源版本，它的出現又讓情況復雜化了。此刻（2010年中期），Oracle對Solaris和OpenSolaris的確規劃沿不明朗。

  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.

  預計在今年的某個時刻發布Solaris 11，迄今為止的種種跡象表明，它會和OpenSolaris很相近。本書中我們稱為“Solaris”的是一種混合系統，它基于產品級的Solaris 10和OpenSolaris的發布版，并根據我們在Oracle內的“臥底”提供的指導做了調整。在不多的幾個地方，我們會指出Solaris 10 還是 OpenSolaris。