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 medium.

Most distributions of Linux use a boot floppy that allows you to enter hardware parameters at a boot prompt to force hardware detection of various devices. For example, if your SCSI controller is not detected when booting the floppy, you will need to reboot and specify the hardware parameters (such as I/O address and IRQ) at the boot prompt. Likewise, IBM PS/1, older ThinkPad, and ValuePoint machines do not store drive geometry in the CMOS (the battery-backed up memory that stores vital information while your computer is turned off), so you must specify it at boot time.

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:

and possibly other messages. What you are seeing here is a boot prompt presented by LILO (the LInux LOader), a program used to boot the Linux operating system and specify hardware-detection parameters at boot time. After you have installed Linux, you may wish to install LILO on your hard drive, which allows you to select between Linux and other operating systems (such as Windows) when the system is booted.

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. If all you have in terms of storage media is an IDE hard drive and CD-ROM, chances are high that you won't have to specify anything.) You can also wait until the installation proceeds. Because today's distributions set a timeout, the installation will only wait for a fixed time for you to enter something and then just continue booting. Thus, if you are unsure what to type, just type any key (like the space key), which will cancel the timeout and give you all the time you want.

If you cannot boot Linux properly without specifying parameters, 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. But in general, the rule is: use the defaults first and see whether that works. Only if it doesn't, should you start to fiddle with the settings. Chances are you will never have to do this, however.

If you don't want to try any hardware-detection parameters now, just press Enter at the boot prompt. Watch the messages as the system boots. If you have an SCSI controller, for example, you should see a listing of the SCSI hosts detected. If you see the message:

SCSI: 0 hosts

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.

To force hardware detection, you must enter the appropriate parameters at the boot prompt, using the following syntax:

linux parameters

There are many such parameters, some of which are listed later in this section. We don't expect you to understand what all these parameters mean or are used for; rather, you should be able to determine which of these hardware options corresponds to your own system. We are presenting a more comprehensive list here, in one place, as you may find them useful later on.

For example, if you have an AHA152x-based SCSI controller, and you know that under Windows 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.

Quite a few other options are available; the previous options 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

Many distributions require you to create Linux partitions by hand using the fdisk program. Others may automatically create partitions for you. Either way, you should know the following information about Linux partitions and device names. (This information applies only to Intel and Alpha systems booted from AlphaBIOS; other systems, such PowerPC, SPARC, and m68k, do not have logical and extended partitions.)

Drives and partitions under Linux are given different names from their counterparts under other operating systems. Under Windows, floppy drives are referred to as A: and B:, while hard-drive partitions are named C:, D:, and so on. Under Linux, the naming convention is quite different.

Table 3-1. Linux partition names

A few notes about this table: /dev/fd0 corresponds to the first floppy drive (A: under Windows), and /dev/fd1 corresponds to the second floppy (B:).

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 Windows, 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:

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 medium, run fdisk by typing:

fdisk drive

Command (m for help): m 
Command action 
   a   toggle a bootable flag 
   d   delete a partition 
   l   list known partition types 
   m   print this menu 
   n   add a new partition 
   p   print the partition table 
   q   quit without saving changes 
   t   change a partition's system id 
   u   change display/entry units 
   v   verify the partition table 
   w   write table to disk and exit 
   x   extra functionality (experts only) 

Command (m for help):

Here is an example of a printed partition table, where blocks, sectors, and cylinders are units into which a hard disk is organized:

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 

Command (m for help):

[7]A block, under Linux, is 1024 bytes.

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

Here, fdisk is asking which type of the partition to create: extended or primary. In our example, we're creating only primary partitions, so we choose p:

Partition number (1-4):

fdisk will then ask for the number of the partition to create; because partition 1 is already used, our first Linux partition will be number 2:

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

Now, we enter the starting cylinder number of the partition. Because cylinders 204 through 683 are unused, we'll use the first available one (numbered 204). There's no reason to leave empty space between partitions:

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

fdisk is asking for the size of the partition we want to create. We can either specify an ending cylinder number, or a size in bytes, kilobytes, or megabytes. Because we want our partition to be 80 MB in size, we specify +80M. When specifying a partition size in this way, fdisk will round the actual partition size to the nearest number of cylinders:

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

If you see a warning message such as this, it can be ignored. fdisk prints the warning because it's an older program and dates back before the time that Linux partitions were allowed to be larger than 64 MB.

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 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 overlaps:

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

As you can see, /dev/hda2 is now a partition of size 82080 blocks (which corresponds to about 80 MB), and /dev/hda3 is 10336 blocks (about 10 MB).

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 want to create additional partitions later.

Command (m for help): w
#

Keep in mind that none of the changes you make while running fdisk takes 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.

3.1.4. Creating Swap Space

[8]Again, some distributions of Linux prepare the swap space for you automatically, or via an installation menu option.

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.

The command used to prepare a swap partition is mkswap, and it takes the following form:

mkswap -c partition

where partition is the name of the swap partition. For example, if your swap partition is /dev/hda3, use the command:

# mkswap -c /dev/hda3

With older versions of mkswap, you had to specify the size of the partition, which was dangerous, as one typo could destroy your disk logically.

The -c option tells mkswap to check for bad blocks on the partition when creating the swap space. Bad blocks are spots on the magnetic medium that do not hold the data correctly. This occurs only rarely with today's hard disks, but if it does occur, and you do not know about it, it can cause you endless trouble. Always use the -c option to have mkswap check for bad blocks. It will exclude them from being used automatically.

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.

The command to enable swap space is swapon, and it takes the following form:

swapon partition

# swapon /dev/hda3

3.1.5. Creating the Filesystems

3.1.6. Installing the Software

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.

The exact method used to install the Linux software differs greatly with each distribution.

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 choose selection by task, because you have to decide whether you need each package; however, 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.

Choosing 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.

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, such as 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 descriptions to see what's in store for you, or you might be surprised when you select the packages and are offered the 25^th text editor.

3.1.7. Creating the Boot Floppy or Installing LILO

If everything goes well, congratulations! You have just installed Linux on your system. Go have a cup of tea or something; you deserve it.