Chapter 3. Installation and Initial Configuration

3.1.1. Booting Linux

The documentation that comes with your particular distribution will explain what is necessary to boot Linux from the installation media.

The boot prompt is often displayed automatically when booting the boot floppy or CD-ROM. This is the case for the Red Hat distribution. With distributions that do not show the prompt by default, you need to hold down the Shift or Control key or press the Scroll Lock key while booting the floppy or CD-ROM if you want to enter something at the boot prompt. If successful, you should see the prompt:

boot:

At this point you have several options. You can press the Enter key to simply boot Linux from the floppy with no special parameters. (You should try this first, and if installation seems to go well, you're all set.) Or, just wait until the installation proceeds, today's distributions set a timeout for the boot prompt, and when you do not enter anything for some time, they just continue booting. Otherwise, you may have to specify hardware-detection parameters at this boot prompt, to force the system to properly identify the hardware installed in your system.

SCSI: 0 hosts

then your SCSI controller was not detected, and you will have to use the hardware detection procedure we'll describe in a moment.

If the automated hardware detection procedures do not work for you (which normally is the case only if you have very old, very new or very unusual hardware), you will have to help Linux a bit by forcing hardware detection.

There are many such parameters, some of which are listed below. We don't expect you to understand what all of these parameters mean or are used for; rather, you should be able to determine which of these hardware options corresponds to your own system. For example, if you have an AHA152x-based SCSI controller, and you know that under MS-DOS you must configure the board for a particular I/O address and IRQ, you can use the corresponding option (aha152x=) here. In fact, many of these boot options are simply unnecessary for initial installation. We are presenting a more comprehensive list here, in one place, as you may find them useful later on.

Quite a few other options are available; the previous options should be those that are generally necessary for normal use of your system. (For example, we have left out the many parameters available for sound card drivers; we urge you to read the appropriate HOWTO documents if you have a life-threatening situation involving use of your sound card.)

For each of these, you must enter linux followed by the parameters you wish to use.

3.1.2. Drives and Partitions Under Linux

Table 3-1. Linux Partition Names

Most systems, of course, do not have four primary partitions. But the names /dev/hda1 through /dev/hda4 are still reserved for these partitions; they cannot be used to name logical partitions.

Here's an example. Let's say you have a single IDE hard drive, with three primary partitions. The first two are set aside for MS-DOS, and the third is an extended partition that contains two logical partitions, both for use by Linux. The devices referring to these partitions would be:

Note that /dev/hda4 is skipped; it corresponds to the fourth primary partition, which we don't have in this example. Logical partitions are named consecutively starting with /dev/hda5.

3.1.3. Creating Linux Partitions

Here we are describing the basic text-mode usage of fdisk which should be available with all distributions. Many distributions nowadays provide a more user-friendly interface to fdisk. While those are usually not as flexible as plain fdisk, they can help you make the right choices more easily. Whatever tool you use, this section is helpful for understanding the underlying concepts. The tools all do more or less the same things in the end; some simply have more sugar-coating than others. You can also make use of the information presented here for fixing or checking something that you suspect didn't go right with the graphical tool.

After booting the installation media, run fdisk by typing:

fdisk drive

To create a new partition, use the n command. In this example, we'll create two primary partitions (/dev/hda2 and /dev/hda3 ) for Linux:

Command (m for help): n 
Command action 
  e   extended 
  p   primary partition (1-4)  
  p

Partition number (1-4):

Partition number (1-4): 2
First cylinder (204-683):

First cylinder (204-683): 204 
Last cylinder or +size or +sizeM or +sizeK (204-683):

Last cylinder or +size or +sizeM or +sizeK (204-683): +80M 

Warning: Linux cannot currently use 33090 sectors of this partition

Now we're ready to create our second Linux partition. For sake of demonstration, we'll create it with a size of 10 MB:

Command (m for help): n 
Command action 
   e   extended 
   p   primary partition (1-4) 
p 
Partition number (1-4): 3 
First cylinder (474-683): 474 
Last cylinder or +size or +sizeM or +sizeK (474-683): +10M

At last, we'll display the partition table. Again, write down all of this information--especially the block sizes of your new partitions. You'll need to know the sizes of the partitions when creating filesystems. Also, verify that none of your partitions overlap:

Command (m for help): p

Disk /dev/hda: 16 heads, 38 sectors, 683 cylinders 
Units = cylinders of 608 * 512 bytes 
   Device Boot  Begin   Start     End  Blocks   Id  System 
/dev/hda1   *       1       1     203   61693    6  DOS 16-bit >=32M 
/dev/hda2         204     204     473   82080   83  Linux native 
/dev/hda3         474     474     507   10336   83  Linux native

This way the installation software will be able to automatically find your swap partitions based on type. If the installation software doesn't seem to recognize your swap partition, you might want to rerun fdisk and use the t command on the partition in question.

In the previous example, the remaining cylinders on the disk (numbered 508 to 683) are unused. You may wish to leave unused space on the disk, in case you wish to create additional partitions later.

Finally, we use the w command to write the changes to disk and exit fdisk:

Command (m for help): w
#

Keep in mind that none of the changes you make while running fdisk take effect until you give the w command, so you can toy with different configurations and save them when you're done. Also, if you want to quit fdisk at any time without saving the changes, use the q command. Remember that you shouldn't modify partitions for operating systems other than Linux with the Linux fdisk program.

You may not be able to boot Linux from a partition using cylinders numbered over 1023. Therefore, you should try to create your Linux root partition within the sub-1024 cylinder range which is almost always possible (e.g., by creating a small root partition in the sub-1024 cylinder range). If for some reason, you cannot or do not want to do this, you can simply boot Linux from floppy.

Some Linux distributions require you to reboot the system after running fdisk to allow the changes to the partition table to take effect before installing the software. Newer versions of fdisk automatically update the partition information in the kernel, so rebooting isn't necessary. To be on the safe side, after running fdisk you should reboot the installation media before proceeding.

3.1.4. Creating Swap Space

Many distributions require you to create and activate swap space before installing the software. If you have a small amount of physical RAM, the installation procedure may not be successful unless you have some amount of swap space enabled.

If you are using multiple swap partitions, you need to execute the appropriate mkswap command for each partition.

After formatting the swap space, you need to enable it for use by the system. Usually, the system automatically enables swap space at boot time. However, because you have not yet installed the Linux software, you need to enable it by hand.

# swapon /dev/hda3

3.1.5. Creating the Filesystems

# mke2fs -c /dev/hda2 82080

If you're using multiple filesystems for Linux, you need to use the appropriate mke2fs command for each filesystem.

3.1.6. Installing the Software

Some distributions offer several different ways to install the software. For example, you may be able to install the software directly from an MS-DOS partition on your hard drive instead of from floppies. Or you may be able to install over a TCP/IP network via FTP or NFS. See your distribution's documentation for details.

For example, the Slackware distribution requires you to do the following:

1. Create partitions with fdisk.

2. Optionally create swap space with mkswap and swapon (if you have 16 MB or less of RAM).

3. Run the setup program to install the software. setup leads you through a self-explanatory menu system.

You might be overwhelmed by the choice of software to install. Modern Linux distributions can easily contain a thousand or more packages spread over several CD-ROMs. There are basically three methods for selecting the software package:

Selection by task

This is the easiest means of selection for beginners. You don't have to think about whether you need a certain package, you just pick whether your Linux computer should act as a workstation, a development machine, or a network router, and the installation program will pick the appropriate packages for you. In all cases, you can then either refine the selection by hand or come back to the installation program later.

Selection of individual packages by series

With this selection mechanism, all the packages are grouped into series like "Networking," "Development," or "Graphics." You can go through all the series and pick the individual packages there. This requires more decisions than if you select it by task, because you still have to decide whether you need it or not, but you can skip an entire series when you are sure that you are not interested in the functions it offers.

Selection of individual packages sorted alphabetically

This method is useful only when you already know which packages you want to install; otherwise you won't see the forest for the trees.

Chosing one selection method does not exclude the use of the others. Most distributions offer two or more of the aforementioned selection mechanisms.

It might still be difficult to decide which package to pick. Good distributions show a short description of each package on screen to make it easier for you to select the correct ones, but if you are still unsure, our advice is this: when in doubt, leave it out! You can always go back and add packages later.

Modern distributions have a very nifty feature, the so-called dependency tracking. Some packages work only when some other packages are installed (e.g., a graphics viewer might need special graphics libraries to import files). With dependency tracking, the installation program can inform you about those dependencies and will let you automatically select the package you want along with all the ones it depends on. Unless you are very sure about what you are doing, you should always accept this offer, or the package might not work afterwards.

Installation programs can help you make your selection and avoid mistakes in other ways. For example, the installation program might refuse to start the installation when you deselect a package that is absolutely crucial for even the most minimal system to boot (like the basic directory structure). Or, it might check for mutual exclusions, such as cases in which you can only have one package or the other, but not both.

Some distributions like SuSE come with a large book that among other things lists all the packages together with short descriptions. It might be a good idea to at least skim those description to see what's in store for you, or you might be surprised when you select the packages and are offered the twenty-fifth text editor.

3.1.7. Creating the Boot Floppy or Installing LILO

Many distributions give you the option of installing LILO on your hard drive. LILO is a program that resides on your drive's master boot record. It boots a number of operating systems, including MS-DOS and Linux, and allows you to select which to boot at startup time.