by Kamran Husain

IN THIS CHAPTER

• Determining What Tools You Have Installed

• The installpkg Utility

• Generating a New Kernel

• Setting the Default Video Mode

• Accessing DOS Files

• Configuring mtools

• Handling Multiple CD-ROMs
• Adding New File Systems

• Linux Loadable Modules

This chapter covers a variety of topics that basically could not fit in other chapters, nor could they justify a chapter by themselves. We cover these topics briefly and provide locations where you can get more information:

• Determining what tools you have installed

• The installpkg utility

• Generating a new kernel

• Setting the default video mode

• Accessing DOS files

• Configuring mtools

• Handling multiple CD-ROMs

• How to address some problems accessing the disc

• Making a file system

The installpkg utility creates *.tgz packages for distributing Linux files. This program has four modes of operation:

• installpkg package_name. By itself, it will install the *.tgz package you specified in the system. For example, installpkg flex.tgz will install flex on your system for you.

• installpkg -warn package_name. This will not do the installation process, but simply tells you what it's about to do.

• installpkg -r package_name. This recursively installs the files in the root directory from your current directory.

• installpkg -m package_name. This will make a package for you given all the files in the directory you happen to execute this is in.

Information about all of the installed packages on your system is stored in /var/adm/packages. Any related script files are stored in /var/adm/scripts.

The removepkg utility is used to remove packages that are listed in the /var/adm/packages directory. There is a -warn option that tells you what files will be removed but are not actually removed yet. Do not use the removepkg utility unless you are absolutely sure that the files in this package are not used elsewhere.

You will have to install a new kernel if:

• After installation, the Linux kernel does not have the features that the boot disk kernel had. For example, when you used the boot disk, you could access your CD-ROM, but the kernel on the hard disk does not recognize it!

• You want to add more features to the kernel. See Chapter 56, "Working with the Kernel."

• The kernel Linux installed for you is very big and you want a leaner, meaner kernel that uses less memory.

To compile a custom kernel for your hardware, follow these steps:

1. If you haven't installed the C compiler and kernel source, do that by running installpkg (discussed above).

2. Use the bootkernel disk you created at the time you installed Linux. At the LILO prompt, enter mount root=/dev/hda1. Ignore any error messages as the system starts up.

3. Change to root.

4. Go to /usr/src/linux.

5. Run the command make config.

6. Choose your drivers and so on.

7. These four commands will build and install the new kernel to work with LILO:

# make dep

# make clean 

# make zlilo 

# rdev -R /newkernel 

You don't have to recompile the kernel to set the default video mode. Just use rdev with the -v switch to set the video mode in the kernel (either on your hard drive or on your boot floppy). For example, to change the kernel in /vmlinuz to prompt for the video mode on bootup, type the following:

rdev -v /vmlinuz -3

To change the kernel on your boot floppy, type

rdev -v /dev/fd0 {video-mode}

These are the valid video-mode options for the kernel: -3 Prompt the user for a response every time

-2 Extended VGA

-1 Normal VGA

The rdev program resides in /sbin. rdev is very handy and also is used to set the root and swap partitions, ramdisk size, and more in a compiled kernel. It means&tm;Ñu don't have to recompb|e the kernel to make these changes. Use rdev -? for a list of options.

You can always mount the DOS directories and disks to get to DOS files. There is a set of tools called mtools that expedites this procedure. Look at the man pages for a complete description of this handy toolset. The following commands are available for Linux:

mattrib	Changes MS-DOS file attribute flags.
mbadblocks	Marks bad blocks on an MS-DOS diskette.
mcd	Changes MS-DOS directory.
mcopy	Copies MS-DOS files to/from UNIX.
mdel	Deletes an MS-DOS file.
mdir	Displays an MS-DOS directory.
mformat	Adds an MS-DOS file system to a low-level formatted diskette.
mlabel	Makes an MS-DOS volume label.
mmd	Makes an MS-DOS subdirectory.
mmount	Mounts an MS-DOS FAT-formatted floppy.
mmove	Moves or renames an MS-DOS file.
mrd	Removes an MS-DOS subdirectory.
mren	Renames an existing MS-DOS file.
mtest	Tests and displays configuration information.
mtools	A public domain collection of programs that enable UNIX systems to read, write, and manipulate files on an MS-DOS file system (typically a disk). Each program attempts to emulate the MS-DOS equivalent command.
mtype	Displays the contents of an MS-DOS file.

An entry in the file /etc/mtools contains the following fields: drive, device, fat, cylinders, heads, sectors, and offset. Two examples of entries from /etc/mtools are

A /dev/fd0 12 80 2 15



C /dev/hda1 16 0 0 0

which define the DOS disk in drive A as accessible through the device /dev/fd0, having a 12-bit FAT, 80 cylinders, 2 heads, and 15 sectors per track; DOS disk in drive C is accessible through the device /dev/hda1, has a 16-bit FAT, and its geometry is simply that of the hard disk where it lives. The last three numbers can be zero if you want; this enables mtools to try to figure out the disk's geometry itself, and perhaps to fail. A 12-bit FAT is common for floppies but might occur in small hard-disk partitions. A 16-bit FAT is common for hard disks.

This is an extract of my /etc/mtools file:

A /dev/fd0 12 0 0 0     # 3.5  1.4 Meg (autodetect)

B /dev/fd1 12 0 0 0     # 5.25 1.2 Meg (autodetect)

C /dev/hda1 16 0 0 0    # 1st partition of my Disk

There are two detailed README files in the mtools.n2 distribution. These files treat compiling and using mtools. There is a file README.mtools that treats only using mtools, which is a part of the MCC interim version of Linux.

Use the following shell script to mount the CD-ROM drive:

#

# This should be run while logged in as root

echo "Execute:  mount -t iso9660 /dev/cdrom /cdrom"

#

mount -t iso9660 /dev/cdrom /cdrom

Although this may not seem to be the appropriate place in the book for the topic of creating file systems to expand your files system space, it is. After you have worked with Linux for a while, you will want extra space for all the files you accumulate. If you are not familiar with the way files work in Linux, you might want to familiarize yourself with Chapter 8, "File System."

In most cases, you will want to expand the /usr partition to allow for more programs. Most programs wind up under the /usr partition by default and it's easy to run out of room. A key point to keep in mind is that you do not have to have your entire file structure on the same drive or under the / (root) directory. The major restriction is that /:, /sbin, /bin, /lib, /dev, and /conf have to exist on the root drive for Linux to boot. Any other file systems, including /usr, can be mounted afterward.

Let's start with the example of adding a new physical drive to your system. You can just as easily extend this example to that of creating new partitions on your existing drive and creating a file system on them.

My example here deals with the hard drive on an IDE controller, so my first drive is addressed as/dev/hda and the second as /dev/hdb. If you have a SCSI controller, you will have /dev/sda and/dev/sdb for the first and second drives, respectively.

You have to do the next operation as root, so read the instructions here carefully and be careful when deleting files. The usual check and balance system of confirming permissions on deleting important files does not apply to the superuser.

Create a new partition on your new disk as we did in Chapter 3, "Installing Linux." You can run fdisk /dev/hdb to run fdisk directly on the second partition. As a summary, you will use the n command to create a new partition, specify the size in +Megabytes, and assign a type 83 for Linux native type of partition. After you have created the new partition, it's a good idea to reboot. Most of the documentation I have read on Linux says that it's not necessary, but I am of the old school of thought about being safe and not sorry.

On your return from the reboot, you will create the extended file system with the mke2fs command. The extended file system is the preferred file system because it allows for clean boots without having to worry about a file system check every time you reboot. The syntax for this command to create a file system is

mke2fs -c partition size-in-blocks

Therefore, to create your new file system with 480,000 blocks, you would use this command:

# mke2fs -c /dev/hdb1 4800000

where the /dev/hdb1 is the first partition on drive B, the -c flag checks the newly created blocks for errors, and the size is 480,000 blocks. Be prepared for an onslaught of messages about inodes, blocks, and so forth. This process may take a while, so be patient.

Now you can mount this new file system with the mount command. First, create an empty directory in your root directory, let's call it /data.

# cd /

# mkdir data

# mount -t ext2 /dev/hdb1 /data

The mount command shown above will mount the file system in the second drive as /data. The -t option specifies what type of file system exists on the new partition. You can now copy files into this new /data partition. Now you can use this partition for extra space.

The problem is that this mount is valid only for the duration while your machine is running. If you want this to be mounted automatically at boot time, you should edit the /etc/fstab file and add the following line:

/dev/hdb1   /data ext2  defaults	1	1 

The line will cause init, the boot process for Linux, to mount the /dev/hdb1 partition on to the/data directory as an extended file system using the default mount parameters.