|By Ibrahim Haddad, Richard Petersen||
|June 15, 2004 12:00 AM EDT||
This article provides a glimpse into Red Hat: The Complete Reference Enterprise Linux and Fedora Edition (with DVD), published by McGraw-Hill/Osborne. It covers what you need to get started with Red Hat Linux - including the overall design of Linux, Linux distributions, and online resources.
As an operating system, Linux performs many of the same functions as Unix, Macintosh, Windows, and Windows NT. However, Linux is distinguished by its power and flexibility, along with being freely available. Most PC operating systems, such as Windows, began their development within the confines of small, restricted personal computers, which have only recently become more versatile machines. Such operating systems are constantly being upgraded to keep up with the ever-changing capabilities of PC hardware. Linux, on the other hand, was developed in a different context. Linux is a PC version of the Unix operating system that has been used for decades on mainframes and minicomputers and is currently the system of choice for network servers and workstations. Linux brings the speed, efficiency, scalability, and flexibility of Unix to your PC, taking advantage of all the capabilities that personal computers can now provide.
Technically, Linux consists of the operating system program, referred to as the kernel, which is the part originally developed by Linus Torvalds. But it has always been distributed with a massive number of software applications, ranging from network servers and security programs to office applications and development tools. Linux has evolved as part of the open source software movement, in which independent programmers joined together to provide free quality software to any user. Linux has become the premier platform for open source software, much of it developed by the Free Software Foundation's GNU project. Many of these applications are bundled as part of standard Linux distributions. Currently, thousands of open source applications are available for Linux from sites like the Open Source Development Network's (OSDN) sourceforge.net, the software depositories rpmfind.net and freshmeat.net, KDE's apps.kde.com, and GNOME's www.gnome.org.
Along with Linux's operating system capabilities come powerful networking features, including support for Internet, intranets, and Windows and Apple networking. As a norm, Linux distributions include fast, efficient, and stable Internet servers, such as the Web, FTP and DNS servers, along with proxy, news, and mail servers. In other words, Linux has everything you need to set up, support, and maintain a fully functional network.
With the both GNOME and K Desktop, Linux also provides GUI interfaces with that same level of flexibility and power. Unlike Windows and the Mac, Linux enables you to choose the interface you want and then customize it further, adding panels, applets, virtual desktops, and menus, all with full drag-and-drop capabilities and Internet-aware tools.
Linux does all this at the right price. Linux is free, including the network servers and GUI desktops. Unlike the official Unix operating system, Linux is distributed freely under a GNU General Public License as specified by the Free Software Foundation, making it available to anyone who wants to use it. GNU (the acronym stands for "GNU's Not Unix") is a project initiated and managed by the Free Software Foundation to provide free software to users, programmers, and developers. Linux is copyrighted, not public domain. However, a GNU public license has much the same effect as the software's being in the public domain. The GNU general public license is designed to ensure Linux remains free and, at the same time, standardized. Linux is technically the operating system kernel, the core operations, and only one official Linux kernel exists. People sometimes have the mistaken impression that Linux is somehow less than a professional operating system because it is free. Linux is, in fact, a PC, workstation, and server version of Unix. Many consider it far more stable and much more powerful than Windows. This power and stability have made Linux an operating system of choice as a network server.
This article discusses the overall design of Linux; Linux distributions; online resources for documentation, software, and newsgroups; plus Web sites with the latest news and articles on Linux.
Red Hat and Fedora LinuxRed Hat Linux is currently the most popular Linux distribution. As a company, Red Hat provides software and services to implement and support professional and commercial Linux systems. Red Hat has split its Linux development into two lines: Red Hat Enterprise Linux and the Fedora Project. Red Hat Enterprise Linux features commercial enterprise products for servers and workstations, with controlled releases issued every two years or so. The Fedora Project is an Open Source initiative whose Fedora Core release will be issued every six months on average, incorporating the most recent development in Linux operating system features as well as supported applications. Red Hat freely distributes its Fedora version of Linux under the GNU General Public License; the company generates income by providing professional-level support, consulting services, and training services. The Red Hat Certified Engineers (RHCE) training and certification program is designed to provide reliable and highly capable administrators and developers help to maintain and customize professional-level Red Hat systems. Red Hat has forged software alliances with major companies like Oracle, IBM, Dell, and Sun.
Currently, Red Hat provides several commercial products, known as Red Hat Enterprise Linux. These include the Red Hat Enterprise Advanced Server for intensive enterprise-level tasks; Red Hat Enterprise ES, which is a version of Linux designed for small businesses and networks; and Red Hat Enterprise Work Station. Red Hat also maintains for its customers the Red Hat Network, which provides automatic updating of the operating system and software packages on your system. You can also use the same Red Hat Network update tool to automatically update Fedora Linux. Specialized products include the Stronghold secureWeb server, versions of Linux tailored for IBM and Itanium-based servers, and GNUPro development tools.
Red Hat also maintains a strong commitment to Open Source Linux applications. Red Hat originated the RPM package system used on several distributions, which automatically installs and removes software packages. Red Hat is also providing much of the software development for the GNOME desktop, and it is a strong supporter of KDE. On Red Hat, GNOME and KDE are configured to appear the same, using a standardized interface called Bluecurve.
Red Hat provides an extensive set of configuration tools designed to manage tasks such as adding users, starting servers, accessing remote directories, and configuring devices such as your monitor or printer. These tools are accessible on the System Settings and Server Settings menus and windows, as well as by their names, all beginning with the term "redhat-config" (see Chapters 4 and 5 of Introduction to Red Hat Linux). Of particular note is the new package management tool that lets you easily install or remove software packages, arranged in recognizable categories.
Note: Though Red Hat supports both the GNOME and KDE desktop interfaces, the Bluecurve interface provides the same look and feel for both desktops, integrating them into one visually similar interface, with menus, windows, and panels appearing approximately the same, though their underlying capabilities differ (see Chapters 6 and 7).
The new release of Red Hat features key updates to critical applications as well as new tools replacing former ones. Red Hat includes the GNOME desktop, the Apache Web server, GNU Compiler Collection (GCC), and GNU Java Compiler (GJC). New configuration tools, including redhat-config-packages for managing software and redhat-config-xfree86 for configuring your display hardware, have been added and others have been updated, redhat-config-networks, for instance, which now supports wireless networks. Red Hat now installs both the Postfix and Sendmail mail servers and lets you seamlessly switch between both.
Installing Red Hat has become a fairly simple process, using a graphical interface with each step displaying detailed explanations and advice. The Red Hat and Fedora distributions organize their installation to cater to several different uses, as a server, a workstation, and a personal desktop. The personal desktop option installs preselected software (such as office and multimedia applications) for home and personal use. It features a streamlined GNOME desktop interface. The workstation option installs desktop, office, development, and administration software. The server option installs all the standard servers, including the mail and FTP servers, along with default configurations and server administration tools. You can also elect to customize your installation, selecting your own mix of installed software.
The Red Hat Fedora distribution of Linux is available online at numerous FTP sites. Red Hat Fedora maintains its own FTP site at fedora.redhat.com, where you can download the entire current release of Fedora Linux, as well as updates and third-party software. Red Hat was designed from its inception to work on numerous hardware platforms. Currently, Red Hat supports Sparc, Intel, and Alpha platforms. See www.redhat.com for more information, including extensive documentation such as Red Hat manuals, FAQs, and links to other Linux sites.
If you purchase Red Hat Linux from Red Hat, you are entitled to online support services. Although Linux is free, Red Hat as a company specializes in support services, providing customers with its expertise in developing solutions to problems that may arise or using Linux to perform any of several possible tasks, such as e-commerce or database operations.
The Fedora ProjectThe Fedora core release is maintained and developed by an Open Source project called the Fedora Project. The release consists entirely of Open Source software. Development is carried out using contributions from Linux developers, allowing them free reign to promote enhancements and new features. The project is designed to work much like other open source projects, with releases keeping pace with the course of rapid online development. The Fedora Core versions of Linux are entirely free. You can download the most current version, including betas, from fedora.redhat.com. You can update Fedora using the Red Hat update agent (RHN) to access the Red Hat Fedora Yum repository. Updating can be supported by any one of several Yum Fedora repositories, which you can configure RHN to access in the /etc/sysconfig/rhn/sources configuration file. The Fedora Project release replaces the original standard Red Hat Linux version that consisted of the entry-level Red Hat release. In addition to the Fedora Core software, the Fedora project will also provide popular compatible packages as part of the Fedora Extras and Fedora Alternative Collections.
Red Hat Enterprise LinuxThe Red Hat Enterprise line of products is designed for corporate, research, and business applications. These products focus on reliability and stability. They are released on a much more controlled schedule than the Fedora Project versions. What was once the low-cost consumer version of Red Hat Linux will be replaced by a scaled-down commercial Enterprise version for consumers and small business. Red Hat offers three Enterprise versions - one for the workstation and two for servers. Red Hat Enterprise AS provides the highest level of support from intense mission critical requirements for all aspects of network support, including servers, databases, and security. Red Hat Enterprise ES provides a similar package, but one geared to mid-level business requirements. The Red Hat Enterprise WS implements a workstation with a wide range of clients that can be used for either Red Hat Enterprise ES or AS networks.
Red Hat DocumentationRed Hat maintains an extensive library of Linux documentation that is freely accessible online (see Table 1). From its home page, you can link to its support page, which lists the complete set of Red Hat manuals, all in Web page format for easy viewing with any Web browser. These include the Reference Guide, the Getting Started Guide, and the Installation Guide. Tip, HOW-TO, and FAQ documents are also provided. Of particular note are the Hardware Compatibility Lists. This documentation lists all the hardware compatible with Red Hat Linux. For PC users, this includes most hardware, with few exceptions. All the Red Hat documentation is freely available under the GNU General Public License. Before installing Red Hat Linux on your system, you may want to check the online Installation guide. This is a lengthy and detailed document that takes you through each step of the process carefully. If your system is designed for any special tasks, be sure to consult the Customization guide, which covers a variety of topics, such as automatic installation on networks using Red Hat kickstart; network services like Samba, Apache, and FTP; system administration tools; and software package installation and management. Red Hat also provides documentation on implementing PPP Internet connections, Samba file sharing, Apache Web server, firewalls, and mail servers.
Red Hat Linux Fedora CoreRed Hat Linux Fedora Core provides several new features, along with improved aspects of Red Hat 8 and 9. Though it does not include the new 2.6 kernel, it does use the latest 2.4 kernel, 2.4.22. Several new features include Bluetooth and ACPI support:
- Enhanced Bluetooth support includes firmware loader, protocol analyzer, and personal network support.
- The Advanced Configuration and Power Interface (ACPI) is supported with the adpid daemon.
- CUPS is now the only print server included. LPRng has been dropped entirely.
- Support is included for DVD+R/RW writers, the dvd+rw tools
- It includes version 3.2.3 of GCC compiler, gcc32.
- Internet Security Protocol (IPSEC) tools are now available.
- The kernel now supports the Exec shield, which makes segments of the kernel nonexecutable, providing greater security.
- The kernel can now prevent certain kernel modules from being loaded, ensuring more centralized control over the kernel configuration.
- The kernel also supports a laptop mode that schedules task to accommodate laptop power-saving features.
- Two older mail clients have been dropped, exmh and pine.
- With the kernel now including the sound support, the sndconfig tool has been dropped.
- As implemented with Red Hat 9, the Fedora Core continues support for the Native POSIX Thread Library (nptl). The thread library allows applications to be organized into separate threads, letting the processor run them more efficiently. With threading, parts of code in different threads can be run at the same time.
- Red Hat is continuing its migration from LILO to GRUB and will soon drop LILO altogether.
- The tripwire intrusion detection software has been dropped due to development constraints.
- Red Hat continues its migration to UTF-8, the Unicode encoding for a Universal Character Set (UCS). UTF-8 is compatible with standard ASCII character files and provides a standardized method for encoding and implementing all languages. UTF-8 is now the default.
- The vsftp FTP server is the only FTP server now included. The older Washington University FTP server has been dropped entirely (wu-ftpd).
- As initiated with Red Hat 8, the Fedora Core continues to refine the Bluecurve interface, providing a seamless graphical GUI for both GNOME and KDE.
Linux OverviewLike Unix, Linux can be generally divided into three major components: the kernel, the environment, and the file structure. The kernel is the core program that runs programs and manages hardware devices, such as disks and printers. The environment provides an interface for the user. It receives commands from the user and sends those commands to the kernel for execution. The file structure organizes the way files are stored on a storage device, such as a disk. Files are organized into directories. Each directory may contain any number of subdirectories, each holding files. Together, the kernel, the environment, and the file structure form the basic operating system structure. With these three, you can run programs, manage files, and interact with the system.
An environment provides an interface between the kernel and the user. It can be described as an interpreter. Such an interface interprets commands entered by the user and sends them to the kernel. Linux provides several kinds of environments: desktops, window managers, and command line shells. Each user on a Linux system has his or her own user interface. Users can tailor their environments to their own special needs, whether they be shells, window managers, or desktops. In this sense, for the user, the operating system functions more as an operating environment, which the user can control.
In Linux, files are organized into directories, much as they are in Windows. The entire Linux file system is one large interconnected set of directories, each containing files. Some directories are standard directories reserved for system use. You can create your own directories for your own files, as well as easily move files from one directory to another. You can even move entire directories, and share directories and files with other users on your system. With Linux, you can also set permissions on directories and files, allowing others to access them or restricting access to yourself alone. The directories of each user are, in fact, ultimately connected to the directories of other users. Directories are organized into a hierarchical tree structure, beginning with an initial root directory. All other directories are ultimately derived from this first root directory.
With the K Desktop Environment (KDE) and the GNU Network Object Model Environment (GNOME), Linux now has a completely integrated GUI interface. You can perform all your Linux operations entirely from either interface. KDE and GNOME are fully operational desktops supporting drag-and-drop operations, enabling you to drag icons to your desktop and to set up your own menus on an Applications panel. Both rely on an underlying X Window System, which means as long as they are both installed on your system, applications from one can run on the other desktop. The GNOME and KDE sites are particularly helpful for documentation, news, and software you can download for those desktops. Both desktops can run any X Window System program, as well as any cursor-based program such as Emacs and Vi, which were designed to work in a shell environment. At the same time, a great many applications are written just for those desktops and included with your distributions. The K Desktop has a complete set of Internet tools, along with editors and graphic, multimedia, and system applications. GNOME has slightly fewer applications, but a great many are currently in the works. Check their Web sites at www.gnome.org and www.kde.org for new applications. As new versions are released, they include new software.
Note: Ximian currently maintains an enhanced version of GNOME called Ximian Desktop at www.ximian.com.
Linux SoftwareA great deal of Linux software is currently available from online sources. You can download applications for desktops, Internet servers, office suites, and programming packages, among others. Several centralized repositories make it easy to locate an application and find information about it. Of particular note are sourceforge.net, freshmeat.net, rpmfind.net, and apps.kde.com.
Software packages are distributed in compressed archives or in RPM packages. RPM packages are those archived using the Red Hat Package Manager. Compressed archives have an extension such as .tar.gz or .tar.Z, whereas RPM packages have an .rpm extension. For Red Hat Fedora Core, you can update to the latest Red Hat RPM package versions of software from their Fedora Yum repository using the Red Hat Update Agent (see Chapter 4). For Red Hat Enterprise Linux, you can automatically download upgrades for your system using the Red Hat Network described. Also, any RPM package that you download directly, from whatever site, can be installed easily with the click of a button using the redhat-config-packages tool on either the GNOME or KDE desktop. You could also download the source version and compile it directly on your system. This has become a simple process, almost as simple as installing the compiled RPM versions.
Red Hat also has a large number of mirror sites from which you can download their software packages for current releases. Most Linux Internet sites that provide extensive software archives have mirror sites, such as www.kernel.org, that hold the new Linux kernels. If you have trouble connecting to a main FTP site, try one of its mirrors. Red Hat also hosts open source projects at sources.redhat.com.
Repositories and archives for Linux software are listed in Table 3, along with several specialized sites, such as those for commercial and game software. When downloading software packages, always check to see if versions are packaged for your particular distribution. For example, rpmfind.net, freshmeat.net, and sourceforge.net are also good places for locating RPM packages.
Linux Office and Database SoftwareMany professional-level databases and office suites are now available for Linux. These include Oracle and IBM databases as well as the OpenOffice and K Office suites. Table 4 lists sites for office suites and databases. Many of these sites provide free personal versions of their software for Linux, and others are entirely free. You can download from them directly and install on your Linux system.
Internet ServersOne of the most important features of Linux, as of all Unix systems, is its set of Internet clients and servers. The Internet was designed and developed on Unix systems, and Internet clients and servers, such as those for FTP and the Web, were first implemented on BSD versions of Unix. DARPANET, the precursor to the Internet, was set up to link Unix systems at different universities across the nation. Linux contains a full set of Internet clients and servers including mail, news, FTP, and Web, as well as proxy clients and servers. Sites for Internet server software available for Linux are listed in Table 5. Most of these are already included on the Red Hat DVD-ROM included with this book; however, you can obtain news, documentation, and recent releases directly from the server's Web sites.
Development ResourcesLinux has always provided strong support for programming languages and tools. All distributions include the GNU C and C++ compiler (gcc) with supporting tools such as make. Most distributions come with full development support for the KDE and GNOME desktops, letting you create your own GNOME and KDE applications. You can also download the Linux version of the Java Software Development Kit for creating Java programs. Perl and Tcl/TK versions of Linux are also included with most distributions. You can download current versions from their Web sites. Table 6 lists different sites of interest for Linux programming.
Online Information SourcesExtensive online resources are available on almost any Linux topic. The tables in this chapter list sites where you can obtain software, display documentation, and read articles on the latest developments. Many Linux Web sites provide news, articles, and information about Linux. Distribution FTP and Web sites, such as www.redhat.com and ftp.redhat.com, provide extensive Linux documentation and software. The www.gnome.org site holds software and documentation for the GNOME desktop, while apps.kde.com holds software and documentation for the KDE desktop. The tables in this chapter list many of the available sites. You can find other sites through resource pages that hold links to other Web sites - for example, the Linux Web site on the World Wide Web at www.tldp.org/links.html.
DocumentationLinux documentation has also been developed over the Internet. Much of the documentation currently available for Linux can be downloaded from Internet FTP sites. A special Linux project called the Linux Documentation Project (LDP), headed by Matt Welsh, has developed a complete set of Linux manuals. The documentation is available at the LDP home site at www.tldp.org. Linux documents provided by the LDP are listed in Table 7, along with their Internet sites.
Most of the standard Linux software and documentation currently available is already included on your Red Hat DVD-ROM. HOW-TO documents are all accessible in HTML format, so you can view them easily with your Web browser. In the future, though, you may need to access Linux Internet sites directly for current information and software.
An extensive number of mirrors are maintained for the Linux Documentation Project. You can link to any of them through a variety of sources, such as the LDP home site, www.tldp.org, and www.linuxjournal.org. The documentation includes a user's guide, an introduction, and administration guides. These are available in text, PostScript, or Web page format. You can also find briefer explanations, in what are referred to as HOW-TO documents.
In addition to Web sites, Linux Usenet newsgroups are also available. Through your Internet connection, you can access Linux newsgroups to read the comments of other Linux users and to post messages of your own. Several Linux newsgroups exist, each beginning with comp.os.linux. One of particular interest to the beginner is comp.os.linux.help, where you can post questions.
This article is excerpted from Chapter 1 of Red Hat: The Complete Reference Enterprise Linux and Fedora Edition (with DVD), published by McGraw-Hill/Osborne, and used here with permission.
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