Using Linux to Teach Unix System Administration

Printing is one of the biggest problems I have dealt with. Since setting up the print spooler requires modifying configuration files and running daemons, I opted for the “quick and dirty” until such time as the students were more experienced. Generally, Yggdrasil Linux sets up the PC printer port as /dev/lp1. For some reason unknown to me, it sometimes establishes /dev/lp0 as the printer port. Keep this in mind in the following discussion.

Files can be printed by using the following command:

cat filename > /dev/lp1

This sends the raw file to the device port.

echo ^v^l > /dev/lp1

Some printers, such as the IBM Proprinter, have a problem printing Unix files using the above method, since they do not insert a carriage return upon receiving only the line feed at the end of a line. As a result, the output will step across the page. In this case you can use a Unix-to- DOS program such as to-dos to convert the file format before printing. Modify the printing command as follows:

cat filename | todos > /dev/lp1 echo ^v^l > \

/dev/lp1

The ultimate solution to the printing problem is, of course, to run the print spooler. However, if the configuration is not done just right, the spooler doesn't work; thus, using the “quick and dirty” way gets the students started. It also helps the students understand the printing process and learn how to debug printer problems.

The /etc directory is symbolically linked to the /ramdisk/var/etc directory; therefore, students have write access to most files needed to administer the system. The files are saved on the diskette in Linux format, and the next time the student reboots the system the changed files are loaded. It is even possible to modify the boot diskette; just be sure to back it up first.

Figure 5. Layout of Linux File System Showing /etc Linkage

After the above steps are completed and understood by the students, they can have full control of the Linux system. There is no need to network and no need to use local hard disks. I hope to include networking and related skills as my class progresses.

Yggdrasil Linux can be set up quite effectively to teach Unix administration. It is inexpensive, relatively secure and the students can use it at home without modifying their PCs. It helps solve the biggest problems I have experienced as an instructor of Unix. Once the hardware is in place and network security issues are addressed, I am looking forward to using Linux to teach networking as well.