Linux Biblen 2008 Edition Boot Up to Ubuntu, Fedora, KNOPPIX, Debian, openSUSE, and 11 Other Distributions phần 5 pps

When installing packages that support automatic configuration through debconf, you’re prompted to answer the appropriate configuration questions. While the Debian package developers have gone to great lengths to ensure that the default options for these questions will work in most situations, it’s best to read the questions thoroughly to be sure that the defaults work for you. Removing Packages APT can also be used to remove packages from your system. Unlike dpkg, which removes only the package you tell it to remove, apt-get also removes any packages that depend on the package you are removing. This is best used in conjunction with the -s option to simulate what would happen if the removal were actually performed: # apt-get -s remove python2.3 Reading Package Lists Done Building Dependency Tree Done The following packages will be REMOVED: bittornado python python2.3 python2.3-dev 0 upgraded, 0 newly installed, 4 to remove and 0 not upgraded. Remv pytris (0.96 Debian:testing) Remv python (2.3.4-1 Debian:testing) Remv python2.3-dev (2.3.4-5 Debian:testing) Remv python2.3 (2.3.4-5 Debian:testing) In this example, several other packages depend on the python2.3 package and also need to be removed. To proceed with removing python2.3 and all packages that depend on it, run the com- mand again without the -s flag. Upgrading Your System As new versions of packages become available, you can instruct APT to download and install them, automatically replacing the older versions. This is as simple as updating your package list, followed by a simple command: # apt-get upgrade APT will begin by downloading the necessary packages, and will then move on to installing and configuring them. If necessary, you can abort the upgrade during the download process by pressing Control+C. APT may also be able to recover if you have to abort during the installation or configuration steps, but it is still best to let the process run without interruption once it has begun installing packages. When upgrading to a newer distribution, use dist-upgrade instead of upgrade. This changes the rules that APT uses when deciding which actions to take, making it expect major changes in dependencies and handle them appropriately. NOTE NOTE NOTE NOTE 320 Choosing and Installing a Linux Distribution Part III 30190c09.qxd:Layout 1 12/18/07 12:25 AM Page 320 Package Management Using dpkg As mentioned earlier, the dpkg utility is the core package management tool in Debian. Most other package management tools within the system, including APT, use dpkg to perform the midlevel work, and dpkg in turn uses dpkg-deb and dpkg-query to handle a number of the low-level func- tions. In most cases, you will want to use APT or aptitude for package management, and use dpkg in only a few situations. Far too many commands associated with dpkg exist to list in this chapter, but the most common ones are explained in the following sections. In most cases, there are both short and long commands to perform the same function. Use whichever is easier for you to remember. Installing and Removing Packages Packages can be installed with dpkg using the -i or install flags and the path to the .deb file containing the package. The path must be accessible as a file system path (HTTP, FTP, and other methods are not supported), and more than one package can be specified: # dpkg install /home/wayne/lsof_4.71-1_i386.deb Package removal through dpkg is also straightforward and is done with the -r or remove com- mand. When configuration files are to be removed, the -P or purge command can be used instead. Both commands can also be used to specify multiple packages to remove: # dpkg remove lsof or # dpkg purge lsof Querying the Package Database You will often need to obtain more information about packages that are already installed on your system. Because these operations do not modify the package database, they can be done as a non- root user. To list all packages known to dpkg, use the -l or list command: $ dpkg list You can restrict the list by specifying a glob pattern: $ dpkg list "*lsof*" The quotes are used to prevent the shell from replacing the wildcard with a list of matching files in the current directory. For more information about wildcards, see Chapter 2 or type man 7 glob to see a list of wildcards. NOTE NOTE 321 Running Debian GNU/Linux 9 30190c09.qxd:Layout 1 12/18/07 12:25 AM Page 321 To view detailed information about a specific package, use the -s or status command: $ dpkg status lsof Package: lsof Status: install ok installed Priority: standard Section: utils The origin package for a file can be determined using the -S or search command: $ dpkg search /bin/ls coreutils: /bin/ls The list of files in an installed package can be viewed using the -L or listfiles command: $ dpkg listfiles lsof /. /usr /usr/sbin /usr/bin /usr/bin/lsof Examining a Package File Package files can be examined before installing them using either the info (-I) or the contents (-c) command. These options can be used on packages in a local directory, as opposed to using them to examine packages on a remote server. The following info option shows the lsof package name, version information, and sizes of dif- ferent parts of the package. Beyond that (although shortened here for space considerations) you would be able to see a list of packages lsof depends on and descriptive information about the package. $ dpkg info lsof_4.71-1_i386.deb new debian package, version 2.0. size 319058 bytes: control archive= 1534 bytes. 557 bytes, 16 lines control 2246 bytes, 32 lines md5sums Package: lsof Version: 4.71-1 The following contents option lets you see the full contents of the package you choose as if you were listing the contents with an ls -l command. You can see the name and path to each file, its permission settings, and file/group ownership: 322 Choosing and Installing a Linux Distribution Part III 30190c09.qxd:Layout 1 12/18/07 12:25 AM Page 322 $ dpkg contents lsof_4.71-1_i386.deb drwxr-xr-x root/root 0 2004-04-03 07:34:41 ./ drwxr-xr-x root/root 0 2004-04-03 07:34:36 ./usr/ drwxr-xr-x root/root 0 2004-04-03 07:34:39 ./usr/bin/ Installing Package Sets (Tasks) with Tasksel Some package sets are too large to be managed practically through meta packages, so tasks have been created as an alternative. Tasks are installed and removed using the tasksel utility. When run without any arguments, tasksel presents a menu from which you can select tasks to install or remove. Do not install any tasks if you plan to use this system in conjunction with the server examples in Chapters 24 and 25. Additional options are available from the command line:  To see a list of known tasks, run tasksel list-tasks.  To list the packages that are installed by a task, run tasksel task-packages <task name> . When a task is removed, all programs associated with that task, whether installed manually or as part of that task, are removed! An example of a popular task to install is the desktop task. The desktop task installs three com- plete desktop environments based on the X Window System: GNOME, KDE, and XFCE environ- ments. Note that this task will take a long time to download and install and requires several gigabytes of disk space to complete. To start the desktop task, run the following: # tasksel install desktop Alternatives, Diversions, and Stat Overrides In cases where there is more than one installed program that provides a specific function, package maintainers have the option of utilizing Debian’s alternatives system. The alternatives system man- ages which program is executed when you run a specific command. For instance, the ed, nano, and nvi packages each provide a text editor. An alternative maintained in the system guarantees that a text editor is accessible through the generic editor command, regardless of which combi- nation of these packages is installed. The system administrator can designate which program is referenced in the alternatives database through the use of the update-alternatives command: # update-alternatives config editor CAUTION CAUTION CAUTION CAUTION 323 Running Debian GNU/Linux 9 30190c09.qxd:Layout 1 12/18/07 12:25 AM Page 323 These are alternatives that provide 'editor'. Selection Alternative 1 /bin/ed *+ 2 /bin/nano 3 /usr/bin/nvi Press enter to keep the default[*], or type selection number: 2 You can also use the all command with update-alternatives to configure every entry in the alternatives database, one at a time. You can find more details by typing the following: man update-alternatives. By default, all alternatives are in automatic mode, meaning that the system automati- cally selects a suitable program from the available candidates. Installing a new candi- date program generally results in the automatic updating of the appropriate alternatives. Manually configuring an alternative disables automatic mode, preventing the system from changing these set- tings without prior knowledge of the system administrator. The Debian package management tools also provide a mechanism for renaming specific files in a package and for overriding the ownership and permission settings on files. Unlike when these changes are made manually using mv, chmod, or chown, changes made through the Debian tools remain in place across package upgrades and re-installations. For example, if you want to replace /usr/bin/users without modifying the coreutils package, you can divert it to /usr/bin/users.distrib: # dpkg-divert local rename add /usr/bin/users Adding `local diversion of /usr/bin/users to /usr/bin/users.distrib' Removing the diversion returns the original filename: # dpkg-divert remove /usr/bin/users Removing `local diversion of /usr/bin/users to /usr/bin/users.distrib' Stat overrides are useful when you want to disable access to a program, or when you want to make it set-UID. For instance, to disable access to the wall program, type the following: # dpkg-statoverride update add root root 0000 /usr/bin/wall This sets the owner and group of /usr/bin/wall to root and root and disables all permissions on the file. You can find more information about file permissions in the section “Understanding File Permissions” in Chapter 2. Unlike dpkg-divert, dpkg-statoverride does not keep track of the original file permissions. As a result, removing an override does not restore the old permissions. After removing the override, you need to either set the permissions manually or reinstall the package that contained the file: NOTE NOTE NOTE NOTE 324 Choosing and Installing a Linux Distribution Part III 30190c09.qxd:Layout 1 12/18/07 12:25 AM Page 324 # dpkg-statoverride remove /usr/bin/wall # apt-get reinstall install bsdutils Reading Package Lists Done Building Dependency Tree Done 0 upgraded, 0 newly installed, 1 reinstalled, 0 to remove and 0 not upgraded. Need to get 0B/62.5kB of archives. After unpacking 0B of additional disk space will be used. Do you want to continue? [Y/n]Y (Reading database 16542 files and directories currently installed.) Preparing to replace bsdutils 1:2.12-10 (using /bsdutils_1%3a2.12- 10_i386.deb) Unpacking replacement bsdutils Setting up bsdutils (2.12-10) Managing Package Configuration with debconf All packages that include support for configuration management through debconf are configured as they are being installed. If you want to change a configuration option later, you can do so using the dpkg-reconfigure command. For instance, you can change the configuration options for ssh using the following command: # dpkg-reconfigure ssh Every configuration parameter is assigned a priority by the package maintainer. This allows deb- conf to select the default values for settings below a specific priority. By default, you will be prompted to answer questions of only medium, high, or critical priority; low-priority questions are answered automatically. You can change this by reconfiguring the debconf package: # dpkg-reconfigure debconf Advanced users maintaining multiple systems may want to create a database of configura- tion settings that can be distributed to every computer (or to sets of computers) to reduce the number of repeated steps. This process is documented in the debconf and debconf.conf man pages. Summary The reliability of Debian GNU/Linux, combined with the large number of high-quality packages available for it, make Debian a great choice for both workstations and servers. The carefully exe- cuted releases and the capability to upgrade most software without rebooting serve to further increase its suitability as a server operating system. APT is a primary tool for installing, removing, and upgrading packages. This chapter explores how to use the apt-get and apt-cache utilities for package management. The chapter also covers the installation of package sets (tasks) using the tasksel utility and managing package configuration with the dpkg-reconfigure utility. NOTE NOTE 325 Running Debian GNU/Linux 9 30190c09.qxd:Layout 1 12/18/07 12:25 AM Page 325 30190c09.qxd:Layout 1 12/18/07 12:25 AM Page 326 F or the past few years, SUSE has been the most popular Linux distribu- tion in Europe. Since the U.S. networking company Novell, Inc. pur- chased SUSE in November 2003, SUSE has been positioning itself to challenge Red Hat to become the dominant Linux distribution for large enter- prise computing environments worldwide. Like Fedora and Red Hat Enterprise Linux, SUSE is an excellent first Linux for people who prefer to work from a graphical desktop rather than from the command line. Likewise, Novell’s Linux product line is geared toward enter- prise computing, so the skills you gain using SUSE on your home Linux system will be useful in a business environment as well. SUSE has a slick graphical installer that leads you through installation and intuitive administrative tools, consolidated under a facility called YaST. SUSE and its parent company, Novell, offer a range of Linux products and support plans that scale from free versions of openSUSE with community support, to supported SUSE distributions for the home and enterprise desktop (SUSE and SUSE Linux Enterprise Desktop), all the way up to SUSE’s Linux Enterprise Server product. In 2005, Novell refocused its development efforts to do as Red Hat does with its Red Hat Enterprise Linux product and Fedora project: Novell formed the openSUSE project, which, like the Fedora project, produces a free community- driven Linux system that feeds into Novell’s for-profit Linux systems. Unlike Fedora and RHEL, however, openSUSE and SUSE Linux Enterprise are, so far, following the same release numbers. They are differentiated by the fact that openSUSE offers no official Novell support and SUSE may contain some non–open source software. The DVD that comes with this book contains the openSUSE 10.3 KDE install CD. ON the DVD-ROM ON the DVD-ROM 327 IN THIS CHAPTER Understanding SUSE What’s in SUSE Getting support for SUSE Installing openSUSE Running SUSE and openSUSE Linux 30190c10.qxd:Layout 1 12/18/07 12:27 AM Page 327 This chapter describes the features and approach to Linux that sets SUSE apart from other Linux distributions. It also explains how to install the openSUSE Linux 10.3 distribution that is included with this book. The current versions of openSUSE and SUSE Linux (10.3) feature the YaST installer, and the cur- rent versions of KDE 3.5.7 desktop environment, GNOME 2.20.0, Firefox 2.0.0.7, GIMP 2.2.17, Apache 2.2.6, MySQL 5.0.45, and OpenOffice.org 2.3.0. All SUSE Linux packages for the current release are listed at www.novell.com/products/linuxpackages/suselinux/ index_all.html and www.novell.com/products/linuxpackages/desktop10/i386/ index_all.html . At the time of this writing, openSUSE 10.3 has just been released. OpenSUSE and SUSE 10.2 fea- ture KDE 3.5.5, GNOME 2.16, Firefox 2.0, and Apache 2.2.3. With the split between SUSE and openSUSE, Linux product names from Novell have changed significantly in the past year. Most significantly, what was previously called SUSE Professional Linux is now called SUSE Linux Enterprise Understanding SUSE and openSUSE If you are looking for a Linux system with the stability and support on which you can bet your business, SUSE offers impressive, stable Linux products backed by a company (Novell, Inc.) that has been selling enterprise solutions for a long time. SUSE’s product offerings range from personal desktop systems to enterprise-quality servers. Running with the Enemy: The SUSE/Microsoft Deal In November 2006, Novell announced that it had struck a deal with Microsoft to further collabora- tion and interoperability with Microsoft products. This deal includes indemnification against patent- related lawsuits, and has raised a fair amount of concern and controversy in the open source community. In reality, Novell hasn’t admitted and doesn’t see any evidence of the use of Microsoft’s intellectual property (IP) in Linux, but indemnification against patent liabilities has become an important part of the Linux scene ever since SCO launched its series of questionable IP lawsuits against Linux. Red Hat and Oracle already offer indemnification against this sort of thing, so this is an even broader level of protection. Paranoia aside, this deal is important if for no other reason than that it is a statement by Microsoft that Linux is important to their customers and a viable enterprise operating system. As always, the long-term effects of this deal remain to be seen, but it should be a good thing for all concerned. Many members of the open source community are concerned that Microsoft will sneak its IP into the GNU/Linux code base, setting the stage for future lawsuits against non-partners (primarily Novell, although Linux companies Xandros and Linspire have signed similar deals). NOTE NOTE 328 Choosing and Installing a Linux Distribution Part III 30190c10.qxd:Layout 1 12/18/07 12:27 AM Page 328 SUSE began as a German version of Slackware in 1992, on 40 floppy disks, and was first officially released on CD (SUSE Linux 1.0) in 1994. Founded by Hubert Mantel, Burchard Steinbild, Roland Dyroff, and Thomas Fehr, SUSE set out as a separate distribution from Slackware to enhance the software in the areas of installation and administration. Although SUSE had success and respect with its Linux distribution, it was not profitable, and Novell’s $210 million offer for SUSE was seen as a good thing both for SUSE and for Linux in general. SUSE was running short on cash, and Novell was looking for a way to regain its stature as a growth com- pany in the enterprise and network-computing arena. In the 1980s and early 1990s, Novell was the world’s number-one computer networking company. Before the Internet took hold, Novell’s NetWare servers and IPX/SPX protocols were the most pop- ular ways to connect PCs on LANs. International training, support, and sales teams brought Novell products to businesses and organizations around the world. Despite Novell’s huge lead in the network computing market, file and printer sharing features in Microsoft Windows and late entry into the TCP/IP (Internet) arena caused Novell to lose its market dominance in the 1990s. Although its NetWare products contained excellent features for directory services and managing network resources, Novell didn’t have end-to-end computing solutions. NetWare relied on Windows for client computers and lacked high-end server products. Novell’s association with the UNIX operating system in the early 1990s makes an interesting footnote in the history of Linux. Novell purchased UNIX System V source code from AT&T and set out to make its resulting UNIXWare product (a UNIX desktop product for x86 processors) a competitor to Microsoft’s growing dominance on the desktop. The effort was half-hearted, and in the mid-1990s Novell gave the UNIX trademark to the Open Group and sold the UNIX source code to SCO (although Novell apparently didn’t transfer full rights to that code). Novell’s purchase of SUSE marks its second major attempt to fill in its product line with a UNIX- like desktop and server product. From the early returns, it appears that Novell is doing a better job with Linux than it did with UNIX. What’s in SUSE Unlike distributions geared toward more technical users, such as Gentoo and Slackware, you can configure and launch most major features of SUSE Linux by selecting menus on the desktop. New Linux users should find SUSE to be very comfortable for daily use and basic administration. Like Red Hat Enterprise Linux, SUSE is made to have a more cohesive look-and-feel than most Linux distributions that are geared toward Linux enthusiasts. In other words, you aren’t required to put together a lot of SUSE by hand just to get it working. Although SUSE is ultimately aimed more toward enterprise computing, it also works well as a home desktop system. Let’s explore what openSUSE and SUSE Linux offer you. 329 Running SUSE and openSUSE Linux 10 30190c10.qxd:Layout 1 12/18/07 12:27 AM Page 329 [...]... Select Booting to see the information that is added to your boot loader (GRUB, by default, but you can use the LILO boot loader as well) The boot loader includes the information needed to boot Linux: the location of the boot loader, the default operating system to boot, and other information 14 Time zone Select Time Zone to change your system’s default idea of the time zone in which you are located 15 Language... desktop, network settings, and graphics setup (X) — to floppy disk, hard disk, or USB memory stick Persistent desktop — You can use the configuration icon to create a persistent KNOPPIX home directory on your hard disk or other medium so that you can store and reuse your 346 30190c11.qxd:Layout 1 12/18/07 12:30 AM Page 347 Running KNOPPIX desktop setup information and any data you save from session to. .. related to video cards and running on laptop computers (See Tables 11- 1 through 11- 3.) Automatic desktop startup — Instead of just dropping you to a command line, KNOPPIX does its best to start up a complete KDE desktop environment Along the way, it adds some nice features, such as desktop icons that give you access to your computer’s hard disk partitions Configuration tools — Some hardware either can’t... each patch and updated package is downloaded and installed Having security-related patches and other fixes separated and having the ability to read all about each software update and patch right on the YaST window before you start downloading are features that make YaST Online Update a powerful and easy -to- use software update mechanism Managing Software with zypper Although the rpm command is good... immediately start using KNOPPIX to browse the Web and otherwise take advantage of its communications tools KNOPPIX will try to detect a DHCP server (to get an IP address and other information) and automatically configure itself to use the Internet or other network that is available If you need a dial -up connection instead, KNOPPIX includes Kppp for configuring a dial -up modem The system requirements... DEL) Look for a selection to change the boot order so that your CD or DVD boots before the hard disk Add boot options — Instead of just letting the boot process autodetect and configure everything about your hardware, you can add options to the boot prompt that will override what KNOPPIX autoconfiguration might do Press F2 from the boot prompt to see additional boot options Some boot options are available... prompt at the bottom The following tables provide boot prompt options that can help you get KNOPPIX 351 11 30190c11.qxd:Layout 1 Part III 12/18/07 12:31 AM Page 352 Choosing and Installing a Linux Distribution running the way you like Table 11- 1 shows options to use when you want specific features turned on that may not be turned on by default when you boot TABLE 11- 1 Boot Options to Select Features... move your partitions around with a tool such as Partition Magic, you should assign your Linux partition to the ext3 file system type (If you are an expert and want to use the fdisk command, press Ctrl+Alt+F2 to get to a shell, run fdisk, and then press Ctrl+Alt+F7 to return to the graphical installer.) 12 Software Select Software to see a list of packages available to install on your hard disk The openSUSE... and Chapter 19 for descriptions of many other bootable Linux distributions Examining Challenges with KNOPPIX For most people, KNOPPIX is a special-use Linux system It’s a great way to try Linux or to access a computer that isn’t set up the way you like However, there are a few challenges with using KNOPPIX that you should keep in mind: Reboot clears out KNOPPIX — Unless you save your data to some other. .. can boot KNOPPIX If it works, you can check to see what drivers were loaded to deal with your hardware (type lsmod from a shell) and then go ahead and install any Linux you like to the hard disk Rescuing a computer or network — Many tools for tracking down and fixing problems on both Linux and Windows systems are included in KNOPPIX There is also a KnoppixSTD edition that includes dozens more tools . the home and enterprise desktop (SUSE and SUSE Linux Enterprise Desktop), all the way up to SUSE’s Linux Enterprise Server product. In 20 05, Novell refocused its development efforts to do as. Enterprise Linux, SUSE is made to have a more cohesive look -and- feel than most Linux distributions that are geared toward Linux enthusiasts. In other words, you aren’t required to put together. to do to install Linux. Hardware detection is done before your eyes. You can set up your disk partitions graphically (no need to remember options to the fdisk command). Setting up the GRUB boot