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/lp1Use the sequence ctrl-vctrl-l. This will send a form feed to the printer and eject the last page of your printout. The second step is necessary because without it the first step will not completely print the file. If you are logged in as guest, make sure you have read/write permissions by typing: chmod 666 /dev/lp1 or chmod 666 /dev/lp0.
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 > \
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.
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.
Joe Kaplenk has been a part-time instructor at the College of DuPage in Glen Ellyn, Illinois for 13 years. He has taught classes in introduction to computers and programming languages as well as Unix. He works full-time for IBM CS Systems in Oakbrook Terrace, Illinois. This article is based on excerpts from a textbook he is writing for teaching Unix administration. Joe enjoys all forms of skating, writing, singing country music songs and country dancing. He also enjoys spending time with his wife Ramona and daughter Anisa. He can be reached at email@example.com.
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