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SSC is expanding Matt Welsh's Linux Installation & Getting Started by adding chapters about each of the major distributions. Each chapter is being written by a different author in the Linux community. Here's a sneak preview--the Red Hat chapter by Henry Pierce.--editor
The Red Hat distribution is an ever-growing and popular commercial distribution from Red Hat Software, Inc. Even though it is a "Commercial" distribution under the Official Red Hat Linux label purchased directly from Red Hat Software Inc., it may be downloaded from the Internet or purchased from third party CD-ROM vendors (see Appendix B) as well.
Much of Red Hat's growing popularity is due to its Red Hat Package Management Technology (RPM) which not only simplifies installation, but software management as well. This in fact, is one of the goals of the Red Hat distribution: to reduce the system administration burdens of obtaining, fixing and installing new packages so that Linux may be used to get some real work done. RPM provides software as discrete and logical packages. For example, the Emacs editor binary executable file is bundled together in a single package with the supporting files required for configuration of the editor and the extension of basic functionality.
The version of Red Hat described here is version 4.0/4.1, released October 1996/December 1996. Installation of earlier installations of Red Hat do differ in their installation procedures than the version described here. Installation of later versions of Red Hat should be very similar to the information given here. This document focuses on Intel based installation of Red Hat Linux. However, many aspects of installing the Alpha and Sparc versions of Red Hat are similar to Intel Systems which are out lined here.
The process of installing or upgrading Red Hat Linux requires backing up the existing operating system, obtaining the Red Hat distribution, planning your installation, preparing the hard disk, making the appropriate installation diskettes, going through the installation program and, finally, rebooting your system with the newly installed operating system. For those who currently have Red Hat Linux 2.0 or higher installed, you may upgrade by following the same process outlined here except you should choose "UPGRADE" instead of "INSTALL" when prompted by the installation program.
There are only two ways of obtaining the Red Hat Linux Distribution: on CD-ROM from Red Hat Software, Inc.\ or other 3rd party CD-ROM distributor or via FTP from: ftp://ftp.redhat.com/pub/redhat or anyone of the frequently less busy Red Hat mirror sites. No matter how Red Hat Linux is obtained, you should read the Red Hat Errata which contains a list of known problems for the release you install. You can obtain the current errata via: http://www.redhat.com/errata or by send email to errata@redhat.com. If you obtained Red Hat Linux from a 3rd party CD-ROM distributor (such as InfoMagic, Inc.) they often delay releasing their CD-ROM kit for 2 weeks to a month+ after a major new release of Linux so they can include the inevitable bug fixes and updates that follow on the CD-ROM an saving the trouble of downloading them. Planning Your Installation
Planning an installation of Linux cannot be understated. The success or failure of installing or upgrading Linux is directly related to how well you know your hardware and understand how Linux should be installed on the target computer. This section outlines basic installation planning and considers common mistakes and oversights that prevent the successful installation of Linux. This is also true for people upgrading Red Hat Linux version 2.0 or higher to version 4.X. In either case, it cannot be understated that you should back up you existing system before going further. In the rare cases that something should go wrong when you have not backed up your system that results in the loss of an existing operating system, your data is lost. So if it is worth saving, back up your system before continuing. I now get off my soap box.
Before we begin, it is worth taking a moment to discuss Red Hat Package Management (RPM) Technology as it is the core of installing and maintaining Red Hat Linux and helps you simplify the planning of installing and provides Red Hat Linux's ability to upgrade from an older version of Red Hat Linux to a current one.
Traditionally, software under Linux and Unix system has been distributed as a series of
package.tar package.tgz package.tar.gzor
package.tar.Zfiles. They often required the system administrator who installs the packages to configure the package for the target system, install the auxiliary and documentation files separately, and setup any configuration files by hand. And if the package requires another supporting package that isn't installed, you won't know a package is missing until you try to use the new package. And the more add-on packages installed, the harder it is to keep track of them. Then if you want to remove or upgrade such a package, you have to remember where all the files for the package are, and remove then. And if you are upgrading a package, and forgot a pesky configuration file, then the upgraded package may not work correctly. In summary, the traditional method of distributing software does provide centralized management system of installing nor upgrading software packages which is crucial to easing the administrative burdens of managing the system.
RPM, in contrast, is designed to manage software packages by defining how a package is built and collecting information about the package and its installation process the during package's build process. This allows RPM to create an organized packet of data in the header of a
package.rpmthat can be added to an organized database that describes where the package belongs, what supporting packages are required, are the required packages installed and a means to determine package dependency information. These are, in fact, describe the design goals of RPM: the ability to upgrade an individual component or the entire system without re-installing while preserving the configuration files for the system/package; be able querying the RPM database to find the location of files, packages or other relevant package information; to perform package verification to make sure packages are installed properly or can be installed at all; to keep source packages "pristine" (provide the package author's original source with second party patches separate) so that porting issues can be tracked. Because RPM does this management for you, you can install, upgrade, or remove a package with a single command line in text mode or a few clicks of the mouse in the X Window Package Management Tool. Simple examples of using RPM from the command line are:
rpm --install package.rpm--this will install package
rpm --upgrade package.rpm--this will upgrade package
rpm --erase package--this will remove/erase package
There are many more complicated things RPM can do such as querying a package to find out if it is installed, what version the package is, or query an uninstalled package for information. In essence, it does almost everything a package management tool should do. And Red Hat has GPL'd this innovative system.
Anatomy of An RPM Package
Essentially, RPM works by maintaining a central database of installed packages, the packages files and its version. A properly built
package.rpmhas all of the following characteristics: its name will identify the package, the version of the package, the build revision of the package, the architecture the package is intended for, and of course the extension "rpm" to identify it as an rpm based package. Take, for example,
bash-1.14.7-1.rpm. The name, itself, contains a lot of useful information: the package is "bash", the Bourne Again Shell, it is version 1.14.7 and it is build 1 of the current version for Red Hat, it was built for an Intel or compatible 386 or higher CPU, and of course, it is in "rpm" format. So, if you see a package called bash-1.14.7-2.i386.rpm, you know it is a second build of bash v1.14.7 and probably contains fixes for problems with build 1 and obviously more current. And while the internal organization of an *.rpm is beyond the scope of this discussion, a properly built package contains an executable file, the configuration files (if any), the documentation (at least man pages for the package), any miscellaneous files directory related to the package, and record of where the packages files should be installed and a record of any required packages. Upon successful installation of a \<package\>.rpm, information about the package is registered in the RPM database. A more thorough discussion of RPM may be found in the RPM-HOWTO available from: http://www.redhat.com/support/docs/rpm/RPM-HOWTO/RPM-HOWTO.html
From the discussion above, you should have the sense that RPM is a powerful tool, so powerful in fact, that Red Hat Linux is one of the few Linux and Unix distributions that can truly claim to upgrade from an old release to a current release. If you are planning to upgrade, you should know that only upgrades from version 2.0 of Red Hat Linux and onward are supported due to major changes in Linux's binary format. Otherwise, upgrades can be performed from the same methods of installation: CD-ROM, NFS, FTP and a Hard Drive. As of Red Hat Linux v4.0, the upgrade option is incorporated into the Boot Diskette instead of being a program. For example, if you upgraded in the past from v2.1 to v3.0.3 and now want to upgrade to version 4.0, you will need to create the Boot Diskette (instead of looking for an upgrade script) just like those installing Red Hat 4.X from scratch. However, it will not reformat you partitions nor delete your configuration files.
Given the scope and variety of hardware, it is not surprising many people become confused. However, taking a little time to collect the following information will save much frustration and the time frustration costs when things don't install or work correctly:
Again, taking the time to list the above information before going further will save you time and frustration and make the installation both easier and smoother. If your system didn't come with literature detailing the above parameters for your hardware, you should consult with your system vendor or the manufacturer of the equipment. Other useful information to have if you are going to be on a network are the TCP/IP networking settings for your system (check with your system administrator for these if you don't already know them).
Red Hat Linux may be installed or upgraded via CD-ROM, FTP, NFS or from an existing Hard Drive partition. Installation nor Upgrading is not supported from floppy diskettes containing Red Hat packages. Which supported method chosen depends on your needs, available equipment, availability of Red Hat Linux and time. For example, if you are a network administrator that needs to update or install 16 Linux boxes over the weekend, an NFS install is generally the most prudent way. If you have a Red Hat CD-ROM for your personal machine, then a CD-ROM install is order or Hard Drive install if your CD-ROM drive isn't supported. If you don't have the CD-ROM and simply want to try Red Hat out and have a couple of hours to spare, then an FTP/Hard Drive install is a reasonable choice with a 28.8 speed modem or faster connection to the Internet. No matter which method you choose, the installation of Red Hat is similar in all cases. To begin, everyone needs to have the following files available and then create the Installation Floppy Kit described below to install Red Hat.
To create the Installation Floppy Kit, you need to obtain the following:
$\backslash$imagesdirectory on a properly laid out Red Hat CD-ROM. Obviously, this is required for all installation methodologies.
$\backslash$imagesdirectory on a properly laid out Red Hat CD-ROM. This diskette is required if you are method of install is not CD-ROM based or you need PCMCIA support for any devices such as a CD-ROM on the laptop to install properly. This diskette can also be used with the Boot Diskette for an emergency start disk for an installed system.
$\backslash$DOSdirectory on a properly laid out Red Hat CD-ROM. This program is run from and existing DOS or Windows 95 system to create usable diskettes from the boot.img and supp.img described above If you have an existing Linux/Unix system, the
ddcommand can be used instead. This is described later in the document.
C:$\backslash$FIPSif you need to free space on your hard drive. This utility can non-destructively shrink and existing DOS 16-bit FAT (Please see Using FIPS for compatibility notes). This will achieve will unpack into the program files FIPS.EXE and RESTORB.EXE which are to be placed on the emergency boot disk made below. Your should also read FIPS.DOC (part of the package fips11.zip) for information on using FIPS not covered in this document.
A note about creating the Boot and Supplemental Diskettes: If you are re-formating existing diskettes, DO NOT use
format /s A:to format the diskettes, just use
format A:. The diskette images need the entire capacity of the diskette and
/sswitch seems to prevent the diskette images from being properly copied to the floppies. For the emergency diskette below, you will of course want to use the /s switch.
One blank DOS formatted floppy is needed to create the Boot Diskette and one blank DOS formatted diskette is needed for the Supplemental Diskette. This diskette set is used for both installing or upgrading Red Hat Linux. Starting with Red Hat 4.0, a "one boot diskette fits all" strategy is employed to install or upgrade Red Hat Linux from the CD-ROM, FTP, NFS or Hard Drive medium. Other distributions (and older RHS distributions require you to match a boot image to your hardware, RHS v4.0 and higher do not). The Boot Diskette is made from the file "boot.img" and is located in the
\imagesdirectory on the Red Hat CD-ROM or can be downloaded from: ftp://ftp.redhat.com/pub/redhat/current/i386/images/boot.img or one of Red Hat's mirror sites. If you are installing to a laptop with PCMCIA hardware, or from a Hard Drive, NFS or FTP you will need to create the Supplemental Diskette made from the file "supp.img" which is located in the
\imagesdirectory on the Red Hat CD-ROM or can be downloaded from: htp://ftp.redhat.com/pub/redhat/current/i386/images/boot.img
The Boot Diskette image contains the bootable kernel and the module support for most combinations of hardware and the Supplemental Diskette contains additional tools for non CD-ROM installs. You should make the Supplemental Diskette even if you are installing from CD-ROM because the Boot and Supplemental Diskette can be used as an emergency boot system if something should go wrong with the install or with your system after it is installed and allow to examine the system.
NOTE: some will notice the size of the boot.img and supp.img being 1.47MB which is larger than 1.44MB. Remember that the unformatted capacity of a 1.44MB is really 1.47MB and that boot.img and supp.img are exact byte for byte images of a floppy diskette. They will fit using one of the tools below:
The utility
RAWRITE.EXEmay be used from DOS, Windows 95 or OS/2 to create the Boot and Supplemental Diskettes.
RAWRITEcan be found in the
\DOSUTILSdirectory on the Red Hat CD-ROM or it can be downloaded from: ftp://ftp.redhat.com/pub/redhat/current/i386/dosutils/rawrite.ext or one of Red Hat's mirror sites. Once you have obtained it, copy
RAWRITE.EXEto
C:\DOSor
C:\WINDOWSdirectory (or other system directory in the command path) which will place the
RAWRITEutility in your command path. From the CD-ROM (presuming it is the D: drive or which ever drive and directory you downloaded RAWRITE.EXE to on the system) to use
RAWRITE, copy it to one of your system directories:
D:\DOSUTILS> copy RAWRITE.EXE C:\WINDOWS
Once rawrite has been copied to a system directory (such as
C:\DOSor
C:\WINDOWS, change to the images directory on the CD-ROM or to the directory you copied boot.img and supp.img to and do the following to create the Boot Diskette:
C:\> D: D:\> cd \images D:\images> rawrite Enter disk image source file name: boot.img Enter target diskette drive: a: Please insert a formatted disk into drive A: and press -Enter-:
Once rawrite is done creating the Boot Diskette, remove the diskette from the floppy drive and label it "Red Hat Boot Diskette". Remember, Red Hat Linux 4.X uses a "one boot disk fits all" strategy so you don't have to worry about matching a boot image to your hardware as earlier distributions of Red Hat required.
To create the Supplemental Diskette, follow the instructions above but substitute "supp.img" for "boot.img". Remember to label this diskette "Red Hat Supplemental Diskette".
If you are creating the Boot and Supplemental Diskettes from and existing Linux or Unix box, make sure it has a 1.44-3.5" floppy available and you know how your system refers to the floppy device. If you don't know how the system accesses the floppy device, ask you system administrator. For Linux, Floppy Drive A: is called /dev/fd0 and Floppy Drive B: is called /dev/fd1. To create the diskettes under Linux, `cd` to the system directory containing the boot.img and supp.img image files, insert a blank formatted diskette and type the following enter
dd if=boot.img of=/dev/fd0to make the Boot Diskette. Once dd is done, remove the diskette from the floppy drive, label it "Red Hat Boot Diskette" and set it aside. Then insert a second formatted diskette and type
dd if=supp.img of=/dev/fd0. Once dd is done, remove the diskette from the floppy drive, label it "Red Hat Supplemental Diskette" and set it aside.
If you are installing Linux to a machine that has an existing operating system, make sure you create an emergency start diskette with useful diagnostic and recovery tools. Exactly how you want to create such a diskette various from operating system to operating system. However, MS-DOS 6.X and Windows 95 will be covered here and should give you some ideas for other operating systems.
Windows 95 users should press "Start---Settings---Control---Panel--- Add/Remove Software" and select the "Startup Disk" tab. Insert a blank, DOS formatted disk and press "Create Disk". When Windows 95 is done, you will have a boot diskette for Windows 95 containing use tools such as FDISK.EXE, SCANDISK.EXE and DEFRAG.EXE. Once the diskette is created, you need to copy
C:FIPS\RESTORB.EXE(obtained and unpacked above) to the Windows 95 Boot Diskette you made. When you are done, remove the diskette and label it "Windows 95 Emergency Boot Diskette and Partition Table Back Up".
MS-DOS 6.X users need to place a blank MS-DOS formatted diskette into floppy drive A: and do the following to create their emergency boot diskette:
C:\> format A:\ C:\> copy C:\DOS\FDISK.EXE A:\ C:\> copy C:\DOS\SCANDISK.EXE A:\ C:\> copy C:\DOS\DEFRAG.EXE A:\ C:\> copy C:\DOS\SYS.COM A:\ C:\> copy C:\FIPS\RESTORB.EXE A:\
Once you are done creating the diskette, remove it from the floppy drive and label it "MS-DOS Emergency Boot disk and Partition Table Back Up".
Once you have created the Installation Floppy Kit, you should ensure your installation method is properly setup for using the Red Hat installation diskettes. For CD-ROM, NFS, FTP and Hard Drive installation methods, the medium must have the directory
\RedHaton the "top level" with the directories
\baseand
\RPMSunderneath:
RedHat |----> \RPMS (contains binary the .rpm s to be installed) |----> \base (contains a base system and files to setting up the hard drive)
CD-ROMs will, of course have additional directories but the key directories needed for the installation are
\RedHaton the top level of the CD-ROM with
\baseand
\RPMSunderneath on third party CD-ROMs. Obviously, Red Hat Software will ensure their Official Red Hat Linux CD-ROM will have the proper directory structure. So, if you are installing from CD-ROM, you may go to Preparing Your System for Installation. For the other types of installs, read the section appropriate section for your installation medium:
For NFS installs, you will either need a Red Hat CD-ROM on a machine (such as an existing Linux box) that can support and export an ISO-9660 file system with Rockridge Extensions or you need to mirror one of the Red Hat distribution with the directory tree organized as indicated above. And of course the proper files in each directory. The directory
\RedHatthen needs to be exported to the appropriate machines on the network that are to have Red Hat Linux installed or upgraded. This machine must be on a Ethernet, you can not do an NFS install via dialup link.
Hard Drive installs need to have the
\RedHatdirectory created relative to the root directory of the partition (it doesn't matter which partition) that will contain the Red Hat distribution obtained either from CD-ROM or an FTP site. For example, on the primary DOS partition the path to
\RedHatshould be
C:\RedHat. On a DOS 16-bit FAT file system, it does not matter that the
package.rpmnames get truncated. All you need to do is make sure
\RedHat\basecontains the base files from a CD-ROM or FTP site and
\RedHat\RPMScontain all the
package.rpmfiles from the CD-ROM or FTP site. The you can install or upgrade from that partition. If you have an existing Linux partition not needed for an installation or upgrade, you can set it up as outlined here as well and use it.
TIP: NFS and Hard Drive installs can provide more flexibility in the packages available to install. NFS and Hard Drive installs/upgrades implied that you can be selective about which packages are placed in the RPMS directory. For example, if you only want a text based system, then the X-based packages may be excluded. Also, if there are updates for the Red Hat system you wish to install, they may be placed in the RPMS directory in place of the distributions original packages. The only caveat for customizing the available packages for installing or upgrading Red Hat Linux is that package dependencies are meet. That is, if package A needs package B to be installed, both packages must be present to meet the interdependencies. This may, however, take a little experimenting to ensure all package dependencies are met. For more information, please see "Customizing Your NFS or Hard Drive Installation" below.
For FTP installs over the Internet, all you need is the IP address of your nearest FTP server and the root directory path for the Red Hat Linux system you wish to install. If you don't know the nearest FTP site, consult with your system administrator or your ISP. If you are intending to do an FTP install over a low band width connection (defined as anything slow than a 128K ISDN link), it is highly recommend that you FTP the file files to a hard drive with an existing DOS partition and then do the hard drive install install described in this chapter. The total size of the binary packages available in the
/RedHat/RPMSdirectory is currently around 170MB which will take many hours to install. If anything goes wrong with the installation such as the link goes down, you will have to start over again. If you ftp the files first, setup your hard drive for installing Linux, it is then less work and less flustering to recover from a failed install. You don't even have to download all the files in
/RedHat/RPMSto successfully install a minimal system that can grow with your needs. Please see Customizing Your NFS or Hard Drive Installation for details.
One of the interesting things you can do with Red Hat Linux is customize the install process. However, this is not for the faint of heart. Only those already familiar with Red Linux or Linux in general should attempt customizing the install. As of Red Hat v4.X, the
/RedHat/RPMSdirectory contains approximately 170MB of rpm files. RPM does compress these packages and can assume the package will need and average 2-3MB of hard drive space for every 1MB of
package .rpmavailable for installation. For example, if the
package .rpmis 6MB in size, you will need between 12 to 18MB of free space to install the package. If you know what software you want and don't want, much of the software provided will not have value for the installation, and for for low band width connects, it is not feasible to download the entire tree. With this in mind, an installation can be customized to remove unwanted software.
Customizing the packages to install is an advantage and possible for the following types of installs: FTP, NFS and Hard Drive methods. CD-ROM cannot be written to (but you can copy the files to the hard drive and do a hard drive install with the customized package list). FTP and NFS installs can only be designed if you have administrator access to the server(s) on your network or your system administrator is willing to work with you. The following installation situations make customizing the installation desirable: Obtaining Red Hat Linux via FTP over a low band width connection or designing a suite of software to be used by all installation of a network of Red Hat Linux boxes.
To customize the installation, you must obtain the
/base/compsfile which will provide you with the list of packages the a full install would normally have. Then then packages you actually want to install from
/base/compsneed be download. Then, the
/base/compsneeds to be edited to reflect the packages you obtained and are going to install. (NOTE: if you have local package.rpms you can add them to the comps file as well).
The Red Hat installation program uses the file
/RedHat/base/comps(the file here is an example from RHS v4.0) to determine what packages are available in the
/RedHat/RPMSdirectory for each category to be installed. The file is organized by category and each category contains a list of packages Red Hat believes are the minimum required for that section. NOTE: only the
packagepart of a packages name
package-version-build.rpmis listed in the file. This means the comps file is generally usable from one version of Red Hat to the next. A section in this file has the structure:
number category package ... end
That is a tag to identify the category number, the category, a list of the package names in the category and the tag "end" to mark the end of the category.
Without exception, everyone needs the all of the software packages listed in the Base section of the file. The other sections, though, generally can be customized or eliminated to suit a particular need. For example, there are three types of Networked Stations: "plain", Management, and Dialup. An examination of these sections shows that many of the software packages are listed in all three categories, but some software packages are specific to the category. If you are creating a Dialup Networked Station, then you can safely eliminate the "Plain" and "Management" sections and any software unique to those categories. Conversely, if you only need basic networking capability for a networked work stations, the other sections can be eliminated from the file as well as the unique software to each of those sections. All you need do is make sure you have the all the software packages listed in that category. If you have some local custom packages (those not provided by Red Hat Software), you should add them to an existing category that is appropriate rather than creating a new category.
Because the list of packages in each category only contains the name of the package, i.e., not the entire
package-name-version-build.rpm, you can substitute any updates Red Hat has made available in the
updatesdirectory on: ftp://ftp.redhat.com/pub/redhat/current/updates
/RedHat/RPMSdirectory. The means installation program is relatively version insensitive. The only caveats here are that package dependencies are met . When an rpm'd package is built, RPM itself tries to determine what packages must be installed for another package to work (the rpm developer also has direct control of this as well---he can add dependencies that rpm might not ordinarily detect). This is where a little experimentation, or research may be needed. For example, one way to determine package dependencies (if you have user access to your NFS server on an existing Red Hat Linux Box) is to telnet or login into it or if you have the CD-ROM, mount it and cd to the
RedHat/RPMSdirectory and query the packages for its dependencies:
[root@happy RPMS] rpm -q -p -R bash-1.14.7-1.i386.rpm libc.so.5 libtermcap.so.2
The "-q" puts RPM in query mode, the "-p" tells RPM to query an uninstalled package and the "-R" tells RPM to list the target package's dependencies required. In this example, we see libc.so.5 and libtermcap.so.2 are required. Since libc and termcap are part of the base of required software (as is bash really), you must insure the libc and libtermcap packages (the dependency packages) are present to be able to install bash (the target). Overall, as long as you get the entire base packages installed, you will be able to boot the system when the Installation Program completes. This means you can add additional packages to Red Hat as required even if the Installation Program reports a package failed to install because dependencies were not met. The following table describes the categories of software are found in
/base/compsinof Red Hat v4.0:
| RPM Category | Required? | Comments |
| BASE | Yes | Should not be customized. |
| C Development | Highly Recommend | Need the minimal system
to compile a kernel |
| Development Libs | Highly Recommend | Need the minimal system
to compile a kernel |
| C++ Development | Optional | C++ Development |
| Networked Workstation | Recommend; Required & Whether you are on an Ethernet or for other network software | going to dialup networking, you
need to install this package suite
You shouldn't customize this. |
| Anonymous FTP/Gopher Server | Optional | If your Linux box is going to
serve files via FTP or Gopher |
| Web Server | Optional | Useful for Web Developers for local
development, required if you serve
web pages. |
| Network Management Workstation | Optional | Has additional tools useful for
dialup as well as Ethernet network |
| Dialup Workstation | Recommended | Required if you are going to dialup |
| Game Machine | Optional | Need I say more? Fortunes are
required for humor :-) |
| Multimedia Machine | Optional | If you have supported hardware |
| X Window System | Optional | If you want to run X |
| X Multimedia Support | Optional | If you have supported hardware |
| TeX Document Formatting | Optional | Customize as needed |
| Emacs | Recommend | The One True Editing Environment |
| Emacs with X | Recommend | Requires X |
| DOS/Windows Connectivity | Optional | Huh? |
| Extra Documentation | Required | Man pages and should ALWAYS
be installed. Other packages optional. |
It is difficult to determine exactly what any one installation will require. However, someone installing via FTP should get the Base system and the Dialup Networked Station and install these. Then additional software can be obtained and added as the need arises. Of course if you want to do C programming, you should get the relevant packages and edit the comps file appropriate.
One last caveat: If you encounter a file during the install that requires another package you don't have available, or you make a mistake in the comps file, you can generally finish the install and have a bootable working system. You can correct the problem by manually adding the failed packages and their dependencies later. Overall, get the entire Base system and a Networked Station packages installed and you can add anything you need or want later.
Before continuing, if you have an existing operating system, and have not yet backed up your data, you must back it up now. While most of the time installing Linux will not result in the loss of data, the possibility exists, and the only way to guarantee a recovery in such a catastrophic event is to back up your data.
At this point with the information collected above and having decided on an installation method above, preparing your system should offer no obstacles. Essentially, you need to make sure you have free and unpartitioned space on one the system's hard drives. (NOTE: there is a file system type known as UMSDOS that some distributions use as an optional way to install Linux onto an existing DOS file system; Red Hat Linux does not support this type of installation.) If you are installing on a system that will only have Linux and does not currently have an operating system installed, then you are set to partition your hard drive and can go to the next section. If you have an existing operating system, such as DOS/Windows 3.1, Windows 95, OS/2 or another operating system, then things are a bit more complex. The following should help determine what you need to do to free hard drive space:
\dosutilscontaining a copy of FIPS.EXE. Otherwise, the FIPS package can be downloaded from: ftp://ftp.redhat.com/pub/redhat/dos/fips11.zip
NOTE: Microsoft has introduced a new 32-bit FAT system with recent Windows 95 releases. This 32-bit FAT system cannot be shrunk by the current version of FIPS.EXE. In Windows 95, if you check under My Computer | Control Panel | System and your Windows 95 kernel version ends in a "B", Windows 95 is likely to be using a 32-bit FAT.
Linux has its own version of the program
fdiskused to create native Linux and swap partitions. However, the details of its use are described later in this guide. However, discussion of the concepts on how to partition your hard drive are important now so reasonable decisions can be made on how much and how to make free space available on the target system.
One way of installing Linux is to use two partitions---one for the operating system and one for the swap file in the free space on your hard disk. However, this is not an ideal way for Linux to be installed. While some hardware configurations may only allow this type of organization, the recommend method is to use a minimum four partitions for Linux: One for
/(the "root" partition), one for
/var, one for
/homeand one for swap. Unlike logical DOS drives which are assigned a drive letter, Linux partitions are "glued" together into one virtual directory tree. This scheme takes advantage of how Linux operates in the real world. Essentially, each file system reflects the life time of a file: the files on the
/partition have the longest "time to live" because they are infrequently updated and often last as long as the operating system itself does on the hardware; The
/homepartition represents medium file life times that can be measured in weeks or days, such as user documents;
/varrepresents files with the shortest life time (such as log files), measured in minutes or even seconds. This type of setup also suggests a backup strategy: the root file system only needs to be backed up when a new program is added or configuration files are changed. The
/homepartition can be put on some sensible full/incremental back up schedule while /var never needs to be backed up, with the exception of
/var/spool/mail. A more through discussion of this can be found in Kristian Koehntopp's Partition mini-HOWTO and Stein Gjoen's Multiple Disks Layout mini-HOWTO.
A PC can have either have a maximum of four primary partitions or have three primary partitions and 1 extended which can contain many "logical" drives. One model in which to understand this are Russian Stacking Dolls. Basically, Russian Stacking Dolls are containers within containers but each container is a discrete doll. A partition is a mechanism describing a container within the master container of the hard drive that an operating system does not leave the confines of. A normal PC hard drive can have up to four primary containers (Primary Partitions) or three primary containers and one extended container (Extended Partition) that contains Logical containers (Logical Drives/Partitions). This means you can have one primary partition for DOS/Windows, one primary partition for the root file system, one primary partition for a swap partition, and one Extended partition containing logical drives for
/varand one logical drive for
/home(as well as other "optionally" defined partitions). However, Linux can and it is often prudent to have more than the partitions outlined here. Due to some design limitations in typical PCs BIOS, there are limitations on how partitions can be setup and still be boot partitions.
Overall, IBM designers didn't think that a PC would ever have 1 GIG drives 15 years ago when the PC was originally designed. As a result, a PC BIOS is limited to a 10-bit address for describing the initial geometry of a hard drive. This happens to correspond to one of the values used in calculating the location of a piece of data on a hard disk known as cylinders. A 10-bit number is sufficient to describe the numbers 0 through 1023 in decimal notation. A drive with 1024 cylinders, 16 heads and 63 sectors per track, is approximately 504MB. This is important for 2 primary reasons: Most boot loaders have to depend on BIOS to get a drives initial geometry for calculating the beginning of a partition and the average drive size on the market these days is 1.2 GIG which contain 2,000+ cylinders. Luckily, most newer system (usually those with a BIOS designed in 1994 or later) have a BIOS that supports Logical Block Addressing (LBA). LBA mode is a means of supporting Large Hard Drives by 1/2 or 1/4 the number of cylinders and doubling (or quadrupling) the number of heads. This allows for the proper calculation of drive geometry while working within the constraints of BIOS. So a drive with 2048 cylinders, 16 heads and 63 sectors per tract will, under LBA mode, have 1024 cylinders, 32 heads, and 63 sectors per tract. Now, we can potentially use any primary partition as a boot partition.
Now, with all this theory and practical advice, it is time to provide some example of how this can be put together; the first example is an 850MB drive with LBA mode enabled which might be divided:
Partition File System Type Use Size /dev/hda1 MS-DOS DOS/Win95 400MB /dev/hda2 Linux Native (ext2) / 325MB /dev/hda3 Linux Swap Swap 32MB /dev/hda4 Extended N/A 93MB /dev/hda5 Linux Native (ext2) /var 40MB /dev/hda6 Linux Native (ext2) /home 53MB
This table might be useful for a machine used by a single person. There a couple of things to note here. First, the labeling of partitions by Linux. The
/devis the Linux directory where "device files" are kept (this is different than a device driver but it is related to device drivers) that Linux uses to identify devices by user programs. The next part,
hda, means "hard disk A" used to designate "Fixed Disk 1" as it is called under DOS. But it also means that the drive is an IDE drive. SCSI drives would use
sdafor "SCSI Disk A. The whole line
/dev/hda1means the 1st partition on hard disk A. As for the sizes that are being used here, they are a little arbitrary, but fall under the following guidelines: A virtual decision was made to use half of the drive for DOS or Windows 95 and roughly half for Linux. So, 400MB was allocated for DOS and it is presumed that is enough for those needs. The
/root file system is 325MB which is enough for the base Linux system (usually about 50MB), programming tools such as C, C++, perl, python and editors such as vi and EMACS as well as the X Window System and some additional space for extra useful packages you might find in the future. If you do not plan to run X, you can subtract 150MB from this total. The swap partition is determined by multiplying 2x physical ram installed on our virtual machine (which has 16MB of core RAM installed). If you are tight on space or have less than 16MB of ram, you should have at least a 16MB swap partition. However, you must have a swap partition defined. 40MB is used for
/varwhich includes enough space for log files and email handling for one or two people. and 53MB for
/homeprovides plenty of space for a user or two to work in.
By now, an installation method has been chosen and a view of what partitioning for Linux has been discussed. But how much space do I really need? The answer is: "It depends." To make a decision on how much space is needed, This a the goal(s) of why you are installing Linux must be reviewed because it has a direct bearing on the space needed to meet these goal(s). If you install everything, you will need about 550MB for all the binary packages and supporting files. This does not include swap space or space for your own files. When these are factored in, a minimum of 650MB or more is needed. If your goal is more modest such as having a text only system with the C compiler, the kernel source tree, EMACS, basic Internet dialup support, then 125 to 150MB of hard drive space is sufficient. If your plans are more demanding such as having a web development platform and X then 450MB or so described in the model above should be enough. If you are planning to start and ISP or commercial web site, then 2 or more GIGs of hard drive space may be needed depending on the scope of services being offered. The overall rule of thumb is having to much real estate is a good thing, not having enough is bad. To help you decide how much space is enough, here are some basic formulas/values for different needs:
| Use of Partition | Recommend | Size Comments |
| Swap | 2 x Physical RAM | If less than 16MB of RAM installed,
16MB is a must. If space is tight,
and 16MB RAM installed, 1 x Physical
RAM is the minimum recommended. |
| Root system, no X | 100 - 200MB | Depends on tools such as compilers,
etc. needed |
| Root system, with X & 250-350MB | Depends on tools such as compilers,
etc., needed |
|
| /home | 5 - Infinite MB | Depends on being single or multiple
users and needs |
| /var | 5 - Infinite | Depends on news feeds, # of users, etc. |
| /usr/local | 25 - 200MB | Used for programs not in RPM format
or to be kept separate from the rest of Red Hat |
Many people installing Linux have one hard drive with a single DOS or Windows 95 partition already using the entire hard drive, or they may have two drives with 1 DOS or Windows 95 partition per drive. FIPS is a utility that can non-destructively shrink a 16-bit DOS FAT in use by DOS 3.X or higher and many implementations of Windows 95. (NOTE: if you are using revision "B" of the Windows 95 kernel, you may be using FAT32 which FIPS currently cannot shrink.) If you meet the requirements above, then you can shrink an existing primary partition on any drive. NOTE: FIPS cannot shrink logical drives or extended partitions. If you have Red Hat on CD-ROM, the utility should be in the
\dosutilsdirectory on the CD-ROM. If you have downloaded Red Hat Linux, you should also download FIPS package available from: ftp://ftp.redhat.com/pub/redhat/dos/fips11.zip
A few caveats about using FIPS: As a reminder, you should back up your existing data before using it. While it is rare for FIPS to damage a partition, it can happen, and backing up your data is the only way to recover from such a catastrophe. FIPS can only be used on primary DOS 16-bit FAT partitions. It cannot be used on any other types of partitions, nor can FIPS be used on Extended partitions or Logical drives. It can only split primary partitions. Before running FIPS, you must run SCANDISK to make sure any problems with your partition are fixed. Then you must run DEFRAG to place all the used space at the beginning of the drive and all the free space at the end of the drive. FIPS will split an existing primary partition into to two primary DOS 16-bit FAT partitions: One containing your original installation of DOS/Windows 95, and one empty, unformatted DOS 16-bit DAT partition that needs to be deleted using the DOS or Windows 95 fdisk program. The following steps outline how to use FIPS.EXE:
FIPS.EXEto
C:\WINDOWSor
C:\DOS. This will place
FIPS.EXEin your command path.
RESTORB.EXEon the disk if you have not already done so. FIPS gives you the ability to back up your existing partition table, allowing you to return your system to its previous state using
RESTORB.EXE.
scandiskand
defrag(included with DOS 6.X and higher). This makes sure there are no errors on your hard drive and places all the free space at the end of the drive.
fips. An introductory message will appear and you will be prompted for which hard drive on which to operate (if you have more than 1). Most people will choose "1" for the first hard disk to shrink.
fdiskto delete the second DOS partition. This will leave unallocated space to be used by Linux's version of f:disk later to create Linux native and Linux swap partitions.
With the appropriate things done in this section for installing Linux, you are now ready to Install Red Hat Linux!
By now, you should have created an Installation Floppy Kit, Prepared Your Hard Drive, and Have your Installation Media ready. for the install. The details of the installation follow, however, you first begin by booting your system and configuring the install program to install from your selected medium. Once this is done, the installation proceeds with the same steps for each everyone one after that. At this point, you need to begin by booting your computer with the diskette labeled "Boot Diskette".
As the boot diskette starts up, the kernel will attempt to detect any hardware which the boot diskette has drivers compiled directly in to it. Once booting is complete, a message asking if you have a color screen appears (if you do, select OK). Next comes the Red Hat Introduction Screen welcoming you to Red Hat Linux. Choose OK to continue. The next questions asks if you need PCMCIA support which you need to say yes to if you are installing to a laptop; say yes and insert the Supplemental Diskette when prompted. Once PCMCIA support is enabled (if needed), you will be presented with a screen asking what type of installation method you will be using. Follow the instructions for the installation method you've chosen described in the following sections.
If installing from CD-ROM, you should choose "Local CD-ROM" by highlighting it from the list of installation types. Once you choose "Local CD-ROM" and click "OK", you will be asked if you have a SCSI, IDE/ATAPI or Proprietary CD-ROM that you wish to install from. This is where some of the hardware research pays off: if you have a recently made 4X or faster CD-ROM drive that was bundled with a Sound Blaster or other sound card, you most likely have an IDE/ATAPI type drive. This is one of the most confusing issues facing you.
If you choose SCSI, you will be asked what kind of SCSI card and be presented a list. Scroll down the list until you find your SCSI card. Once you have choose it, you will be asked if you wish to AUTOPROBE for it or SPECIFY OPTIONS. Most people should choose "AUTOPROBE" which will cause the setup to scan for your SCSI card and enable the SCSI support for you card when found
Once the Installation Program has successfully located the Red Hat CD-ROM, you should proceed to "Walking Through the Rest of the Installation."
If you are installing from a hard drive, then highlight this option and choose "OK". If you have not already choose PCMCIA support, you be prompted to insert the Supplemental Diskette.
If you are installing via NFS, then highlight this option and choose "OK". You will next be asked to choose which Ethernet card you have installed on the target machine so the Installation Program may load the correct Ethernet driver. Highlight the appropriate card from the list and then select "OK" allowing the Installation Program to AUTOPROBE for you card. However, if you machine hangs, you will need to do
Ctrl-\Alt-Deleteto reboot the system. Most of the time, when this happens, it is because the probing "touches" a non Ethernet card. If this should happen, try again and choose "SPECIFY OPTIONS" and give data about your card in the form of:
ether=IRQ,IO\_PORT,eth0This will instruct the probe to look at the location specified by the values
IRQand
IO\_PORTfor an Ethernet card. For example, if you Ethernet card is configured for IRQ 11 and IO\_PORT 0x300, you would specify:
ether=11,0x300,eth0
Once your card has been successfully found, you will be prompted for TCP/IP information about your machine and the NFS server with the Linux installation. First, you will be asked to provide the target machines IP Address, Netmask, Default Gateway, and Primary Name Server. For example:
IP Address: 192.113.181.21 Netmask: 255.255.255.0 Default Gateway: 192.113.181.1 Primary Nameserver: 192.113.181.2
Once you press OK, you will prompted for the target machines Domainname and Hostname. For example, if you domain name is infomagic.com and hostname is vador, enter:
Domainname: infomagic.com Host name: vador.infomagic.com Secondary nameserver IP: Enter if needed Tertiary nameserver IP: Enter if neededThe last screen will prompt you for the NFS server and the exported directory containing the Red Hat distribution. For example, if you NFS server is redhat.infomagic.com, enter:
NFS Server name: redhat.infomagic.com Red Hat Directory: /pub/mirrors/linux/RedHatAgain, if you do not know these values, check with you system administrator. Once you have entered the values, choose "OK" to continue. If the Installation program reports and error locating the Red Hat distribution, make sure you have the correct values filled in above and that your network administrator has given the above target machine information export permission.
An FTP install is very similar to the NFS install outlined above. You will be prompted for the Ethernet card and your machines TCP/IP information. However, you will be asked for the FTP site name and Red Hat directory on the Red Hat mirror site. instead of NFS server information. There is one caveat about performing an FTP install: find the closest and least busy FTP site to your location. If you don't know how to do this, check with your network administrator.
TIP: If your hardware isn't detected, you may need to provide an
override for the hardware to be enabled it properly. You may also want
to check:
http://www.redhat.com/pub/redhat/updates/images
to see if Red Hat has updated boot diskettes for your hardware.
Command (m for help):
This rather mysterious prompt is Linux's fdisk's command prompt. If you press `m`, you will get a list of commands with a short definition of what each does. However, the most useful one to start with is "p". This will print your existing partition on the screen. If you have existing partition(s) on the drive they will be displayed. Make sure you can create at least one 25-50MB partition that starts before cylinder 1024 and ends on or before cylinder 1023 as this type of locations is required by LILO to be able to boot the root partition which will in turn allow the kernel to take over you system which is not restricted in the way LILO is. Once the kernel boots your system, it queries the hardware directory and ignore BIOS.
To create a primary root partition of 50MB according to our example above, enter "n". First, you will be asked for a partition number between one and four. Our example in Planning to Partition the Hard Drive suggests two. You will be asked if the partition is to be a primary or extended, enter `p` primary. Next you are asked to enter the beginning cylinder which should be the first available cylinder from the range given. After you hit enter, you will be asked for the ending cylinder. Since we want to make this partition 50MB, you can enter +50M and fdisk will calculate the nearest ending cylinder for a space of about 50MB. Once you have done this, enter the "p" command so you can make sure the new partition ends on or before cylinder 1023. If the new partition doesn't, use the "d" command to delete partition two and try again except enter +40MB for the new primary partition and check again with the "p" command. Keep doing this until you get a root partition below cylinder 1024. Overall, if you cannot create a root partition of at least +25M below cylinder 1024, then you will either need to free more space below cylinder 1024 or not use LILO.
Next, according to our example, you will want to create a swap partition that is 2 x physical ram installed. Creating a swap partition requires two steps, first using the "n" command to create a primary partition (three in the example). Following the instructions above, except enter the value of +(2 x physical RAM) MB. For the swap and other partitions, we don't care what there beginning and ending cylinders are because they are not crucial for LILO to work correctly---only the root partition is. Once you have created the Linux native partition to be used as the swap partition, you need to use the "t" command to change the partition ID to type "82" when prompted. This changes the partition ID so Linux well recognize it as a swap partition. When you have successfully done this, the "p" command will report that you have a native Linux partition and a Linux swap partition.
Now, since we need two more partition, but the hard drive in a PC can only support four primary partitions and three primary partitions have been used, we need to create an Extended partition that occupies the rest of the drive that will allow the creation of Logical drive with end the extended partition. This time, to create the Extended partition with the "n" command, enter four for the partition number and choose "e" when prompted to create an Extended partition. When asked for the beginning cylinder, use the first one available and for the last cylinder, enter the last available cylinder. You are now ready to create Logical drives for
/varand
/homeaccording to our example.
To create a logical drive of 40MB to be used as
/var, enter "n" to create a partition. Because there is no longer a choice of Primary or Extended, you are not prompted for this information but instead asked if this is to be partition five.
Once you have completed this, you will be asked for the starting cylinder which should be the first available cylinder. For the ending cylinder, enter +40M for the size as the size was entered above. For the
/homepartition, you may have a choice. If your drive is larger than the 850MB suggested in the example, you can enter +53Mb as indicated above and use the extra space for partition such as
/var/spool/mailand
/usr/local. Otherwise, just use the last available cylinder to define
/home. Once you are done creating partitions, you can use the "p" command to print the partition one last time to review it. However, you won't modify any thing until you use the "w" command to write the partition out to the hard disk. If you decided not to modify the partition table at this time, choose "e" to exit without modifying the partition table. NOTE: When creating Logical partitions, you must reboot the system in order for Logical Partitions to be usable. Simply go through the options as you did up to being asked to partition you drive. However, say no the second time around and proceed to the next step.
A:\> fdisk /mbr. This will allow your system to boot into an existing DOS or Windows 95 system as it did before LILO was installed. You can then use the Red Hat Boot Diskette from v4.1 with the following parameters at the boot: prompt to you system on the hard drive:
boot: rescue root=/dev/???? ro load\_ramdisk=0
????is the root partition such hda2 in the example used in this document.
Once the installation procedure is completed, you are ready to reboot your system and use Linux!
Now that you have installed Linux and are booting your system for the first time, there are some useful things to know about using your system such Understanding the LILO prompt, Logging In for the First Time and Using RPM.
If you have installed LILO to manage one or more operating systems, the following useful things should be known:
When you power-on or reboot the system you get the "LILO" prompt which you have hopefully configured for a 30 second or so delay before it boots the system. When LILO appears on the screen, if you do nothing, the default operating system will boot at the prescribed time out period. However, from LILO, you can control several aspects of how Linux boots, or tell LILO to boot an alternative operating system. If you wish to override the default behavior of LILO, pressing the
Shiftkey at the appearance of LILO will cause a "boot:" prompt to appear. Pressing
Tabat this prompt will produce a list of available operating systems:
LILO boot: dos linux boot:
This tells use that "dos" is the default operating system that will boot if nothing is typed, or to boot Linux, type "linux" (without the quotes). However LILO lets you pass overrides to the Linux kernel which will override the kernels default behavior. For example, you may have been experimenting with the start-up configuration files and done something that prevents the system from coming up properly, so you want to boot the system up to the point (but not after which) it reads the configuration files. The override for this is "single":
boot: linux single
Now that you are faced with the "login:" prompt for the first time you may be wondering how to get into the system. At this point on a newly installed system, there is only one account to login to which is the administrative account "root". This account is used to manage your system and doing such things as configuring your system, adding and removing users, add/removing software, etc. To login into the account, type "root" (without the quotes) at the login: prompt and hit enter. You will then be prompted for the password you entered during setup. Enter that password at the password: prompt. The system prompt
[root@locahost] #will appear once you have successfully negotiated the login. The system prompt tells you two things: you are logged in as "root" and in this case your machine is called "localhost". If you named your machine during the installation process, then your machine name will appear instead of "localhost". Now that you are logged in, you can use such commands as
lsto list files,
cdto change directory, and
moreto look at the contents of ASCII test files. The root account also has its own home directory,
/root. A home directory is where a valid system accounts places you in the file system hierarchy once you have successfully logged in. Some Unix systems use
/instead, so don't be fooled if you don't see any files if you type "ls"; there aren't any in the root home directory.
One of the first things you should do on a newly installed system is to create a regular user account for yourself and plan on using the root account only for administrative functions. Why is this important? Because if you make a critical error in manipulating files you are working on, you can damage the system. Another reason is that programs run from the root account have unlimited access to the system resources. If a poorly written program is run from the root account, it may do unexpected things to the system (because a program run as root has root access, a program run as a user has restricted resource access) which will also damage it. To create a user account, you will want to use the
adduserand
passwdcommands:
[root@bacchus]# adduser hmp
Looking for first available UID...501
Looking for first available GID...501
Adding login: hmp...done.
Creating home directory: /home/hmp...done
Creating mailbox: /var/spool/mail/hmp...done
Don't forget to set the password.
$[$root@bacchus$]$\# passwd hmp
New password: \textsl{new\_passwd}
New password (again): \textsl{new\_passwd}
Password Changed.
passwd: all authentication tokens updated successfully
The new account is now be created and is ready to use. Other things that may need to be done as root are configuring X Window System, configuring dialup services, and configuring printer services. These topics are covered elsewhere.
One concept under Linux for accessing devices that confuses new users is that things like CD-ROM disks and floppy diskettes are not automatically made available when inserted in the drive. Linux abstracts a device to be file (although in the case a special type of file), And much like a word processor, you have to tell the system that you want to open a file or close a file. The command used to open (make a device available) a device is
mountand the command to close (tell the system you are no longer using a device) is
umount. When you open a device under Linux, you make it part of the directory tree and navigate with the
cd,
lsand
cp(copy) command normally. Red Hat Linux suggests making removable or temporary devices available under the directory
/mnt. They create the directory
/mnt/floppyby default, but not
/mnt/cdrom. So, the first time you want to access the CD-ROM, you will need to create the directory
/mnt/cdromby typing:
[root@bacchus]\# mkdir /mnt/cdrom
Once you have created the directory, you can access the CD-ROM by typing:
[root@bacchus]\# mount -t iso9660 -r /dev/\textsl{cdrom\_device} /mnt/cdrom
The break down of the command line above is this: the "-t" switch tells the mount command the next argument is a file system type, in this case "iso9660" is the format on most computer CD-ROM diskettes. The "-r" is a read-only flag since the CD-ROM is read-only. The next argument,
/dev/{\sl cdrom\_device}, is the
device file you wish to open. If you performed a CD-ROM install, you
want to replace \textsl{cdrom\_device} with the designation of your
CD-ROM such as:
| Device File | CD-ROM type |
| hd[a,b,c,d] | for IDE/ATAPI CD-ROMs |
| scd[0,1,2,...] | for SCSI cdrom drives |
| sbpcd | for Sound Blaster 2X speed drives |
| mcd or mcdx | for Mitsumi 2X drives |
There are other drive types as well, but these are the most common. Some literature refers to
/dev/cdromwhich is a symbolic link. For example, if you have a Secondary IDE/ATAPI drive set as the master drive, the command:
ln -sf /dev/hdc /dev/cdrom
/dev/cdromas well as
/dev/hdc.
Floppy drives are assessed in a similar manner:
mount -t msdos /dev/fd0 /mnt/floppy
Will make a floppy formatted under DOS in drive "a" available under the directory /mnt/floppy. If you want to access the floppy diskette in the b drive, substitute /dev/fd1 for /dev/fd0.
When you are finished with a device such as a CD-ROM or floppy diskette, it is extremely important that you "close" the file before removing it from the system. This needs to be done for a variety of reasons, but if you don't and try to remove it you can make the system unstable and floppies may get erased. To release a device from the file system, type:
umount /dev/fd0 (to un-mount a floppy) umount /dev/cdrom (to un-mount a cdrom drive)
For more information on either of these commands, please see the man pages (e.g., by entering
man mount).
It is extremely important that the power is not simply shut off while Linux is running. You can damage or even make the system un-bootable by doing so. The proper way to shutdown Linux is to log in as root and type:
[root@bacchus]\# shutdown -h now
The system has halted, it is safe to turn the power off. If you want to reboot the computer with out shutting of the power, use:
[root@bacchus]\# shutdown -r now