Using Linux to Teach Unix System Administration

A teacher at the College of DuPage in Illinois, has found that teaching system administration to beginners is both easy and cost-effective using Yggdrasil Linux.
Getting to login

When you are done entering the linux command-line options, press enter. After all the messages detailing unsuccessful checks for various hardware devices, the system gives you a login prompt. The following four options are displayed on the screen:

  1. demo--gives an X-windows demo program that runs very slowly from the CD-ROM on the first use, but runs much more quickly once it is in memory.

  2. guest--sets up a guest login with normal user rights. This is useful for teaching labs in which students need to determine access rights for certain files and directories by accessing them as guest.

  3. install--allows you to install Linux and gives several menus on the screen.

  4. root--gives you permissions to all files and commands.

File System Structure

For the purposes of this discussion, a root login is assumed. When you type the mount command without arguments, the screen output will look similar to the following:

/dev/hdd on  / type iso9660

/dev/ramdisk on /ramdisk type ext2 (rw) /proc on on type /proc (type)

/dev/hdd refers to the CD-ROM mounted as root. /dev/ramdisk refers to the file system named /ramdisk, which is using internal RAM and can to be altered. /proc is the standard Unix pointer location for devices.

Figure 2. Initial Layout of Linux File System

I have my students enter the following command:

mkdir /ramdisk/mnt  /ramdisk/dos

This command creates two directories on /ramdisk to be used as follows:

  1. /ramdisk/mnt is used to mount a Unix-formatted diskette.

  2. /ramdisk/dos is used to mount a DOS-formatted diskette.

Creating a Linux File System on the Diskette

You format a 1.44MB diskette by typing the command:

fdformat /dev/fd0h1440

The following output will appear on the screen:

Double sided, 80 tracks, 19s sec/track. Total capacity is 1440
KB formatting...done verifying... done

Note that formatting will destroy any files already on the diskette you insert.

Now, to create a Unix file system on the diskette, type the following command:

mkfs /dev/fd0H1440

You can then mount the diskette by typing:

mount /dev/fd0H1440 /ramdisk/mnt
Now, when you type mount alone, the following output appears on the screen:
/dev/hdd on / type iso9660 (ro)
/dev/ramdisk on /ramdisk type ext2 (rw) /proc on on type /proc (type) /dev/fd0u1440 on /ramdisk/mnt type ext2 (rw)

Linux files can now be saved to /ramdisk/mnt. To unmount the diskette use the command:

umount /ramdisk/mnt


umount /dev/fd0H1440

Figure 3. Layout of Linux File System with UNIX Diskette

Using an MSDOS-Based Diskette and Files

It is sometimes necessary to transfer student assignments from the Linux box to the AIX box. Because networking is not done under Linux, it is necessary to use the diskette as the transfer media. The transfer is done using FTP from a DOS/Windows PC to the AIX box.

You will need to format the diskette under DOS. (Be sure you unmount any diskettes from the above exercise.) DOS formatting is done in Linux with the command:

mformat a:

Mount the DOS diskette with the command:

mount -t msdos /dev/fd0H1440 /ramdisk/dos
Typing mount alone produces the following output:
/dev/hdd on / type iso9660 (ro)
/dev/ramdisk on /ramdisk type ext2 (rw) /proc on on type /proc (type) /dev/fd0u1440 on /ramdisk/dos type msdos (rw)

You can now save files in DOS format to /ramdisk/dos. Note that you must use the standard DOS file naming convention of up to 8 characters for the prefix, then a period, then up to 3 characters for the extension. You can unmount the diskette with the command:

umount /ramdisk/dos

Figure 4. Layout of Linux File System with DOS Diskette