"Unix SIG Notes"

I have installed and upgraded several programs since last month. First,
Selection 1.7 was released for kernels greater than 1.1.35. It's main
new feature is support for xterm-like cutting-and-pasting (Ctrl + click)
between virtual terminals (VTs). I got sendfax working and successfully
faxed my resume several times. It was fairly easy to make letterhead
with the graphics tools available under Linux. I also figured out how to
back up my system onto QIC-80 tapes with the ftape module. So "crash
what crash may!" I've been following the cutting edge in kernel
development for awhile. Since the recent alpha kernels are getting
pretty stable (1.2.0 should be out by October), I have included some
tutorial notes on upgrading a kernel. Finally, Linux is being ported to
MIPS, Digital's Alpha AXP, the PowerPC, and the Motorola 680x0 family of
processors. Some day Linux may run on all the popular processor families.

Recently I've been coming to grips with a disease I've recently
acquired: "Linux arrogance." The chief symptom is that if a program
isn't freely redistributable, available with source code included, and
of very high quality, I dismiss it as "junk." Virtually everything I
need is free, just like the air, and I can't stand suffering with the
restrictions imposed on most software! Does anyone know the cure for my
affliction?

Next month George E. will demo a Linux CD-ROM on his laptop (Note: at
the time of this writing it has not yet been tested, so cross your
fingers).

"Upgrading your Linux kernel"

I have put recent versions of the Linux kernel on PACS's Multi-SIG
board. To retrieve the files, log in under your PACS' username. Then
type "B" to go to the <B>bs files areas. At the prompt "Which
Area?(list)>" type "unix". There are two important items on the menu.
First "<L>ong List (selective files)" will let you see the files
available and "<D>ownload Files" does its thing too. As usual typing
<ENTER> will bring the menu up again. There is a Linux files area. The
kernels are identified by version number (1.0.x are stable versions,
1.1.x are beta versions some of which are stable, and soon there will be
a 1.2.x series which will be very stable releases). So I thought I might
walk everyone through installing them.

The kernel in Unix is the program that loads into memory when you boot
the system. It "runs" the show. Accepting, rejecting and scheduling
computer resources for each request from users' programs. Since recent
versions of the beta kernels have been reported to be quite good, I
decided to follow the "bleeding edge" for awhile. So I downloaded and
installed in turn versions 1.1.38-42,46,47 and probably others by the
time you read this. Versions 1.1.41 to 1.1.44 had a serious bug for some
users, but .41 and .42 worked for me. Since some of my suggestions and
hints may be incomplete, I highly recommend that you carefully read the
README file found in /usr/src/linux for further information. Note: Some
programs will not work with the newer kernels. Also you will need the
bdflush-1.4 package which is a backward compatible drop-in replacement
for update (read its Makefile for installation clues).

Some kernels are released as complete kernel trees while others are
patches to be applied to the previous version. For example, 1.1.35 was
released as a full kernel source tree, but you had to get patch36.gz,
patch37.gz, ... , and patch42.gz in order to make version 1.1.42. To
install a new version first "cd /usr/src; rm -r linux; tar xzf
1.1.35.tgz" to install the .35 kernel. (This version probably won't be
available on the BBS when this article gets to press, choose the latest
available.) The kernel tree should now be in place in the linux
directory. You can now apply the patches. The basic command is "gzip -cd
patch??.gz | patch -p0." (NB. The current directory ($PWD) is important
when applying patches - consult patch(1).) Next check to see if the
patching was successful: "cd linux; find . \( -name "*.rej" -o -name
"*#" \) -print." If there were no rejects, you can save some disk space
with "find . -name "*.orig" -exec rm {} \;".

Next to build the kernel. First, "make mrproper" then "make config."
This asks a series of questions about your setup. Unless, you plan on
sharing kernel images with other machines, it is best to make your
kernel as trim as possible. Don't include any unnecessary device drivers
or unnecessary features. For example if you have a math coprocessor,
choose "N" to the first question "Kernel math emulation
(CONFIG_MATH_EMULATION) [n]." Since some daemons and X programs need
TCP/IP support it is wise to answer Yes to "Networking support
(CONFIG_NET) [y]" even if you are not on a network. Finally, if you have
a Microsoft (or perhaps any standard serial) mouse, you can probably
answer "N" to all the mouse driver questions (I do and the mouse works
fine). Some drivers may conflict with others, so it is really best to
eliminate all the unnecessary ones. Feel free to run "make config" as
many times as you like. This is an important step and it may take more
time to fix the problem of an omitted or extra driver later than to get
it right the first time. E-mail me at cfearnl@pacs.pha.pa.us or call
at 349-9681 if you get stuck.

Then "make dep" and finally make your kernel image (make zImage or make
zdisk). Recent kernels (since about 0.99) have an option "make zlilo"
which I like. In order for "make zlilo" to run lilo properly you have to
make certain the kernel and /etc/lilo.conf agree on the kernel location.
"make zlilo" expects the last kernel image to be in /vmlinuz. It will
"mv /vmlinuz /vmlinuz.old" (which will delete any previous
/vmlinuz.old). So you must edit /etc/lilo.conf to make an entry for
/vmlinuz and /vmlinuz.old. Once this task is complete running "make
zlilo" makes the kernel, moves the files automatically, and runs lilo.
[Once you've built a few kernels or as a prophylaxis for the day when
you build a bad kernel, you might do something like "mv /vmlinuz.old
/vmlinuz.1.1.41" (or whatever version number is correct) before you make
your new kernel (adjust lilo.conf to install this, of course). It is
very good practice to keep a few old, reliable kernels about -- "just in
case."]

If you are running the Slackware distribution, the kernel image must be
configured to mount root "/" readonly (ro). The actual command you will
need to run is "rdev -R /vmlinuz 1" (see rdev(8) for more details).

See it's not difficult at all. Happy hacking!


Who Should (and who shouldn't) Switch to Linux?

Linux is at a cross-roads. Six months ago it was mainly useful to
hobbyists, hackers, cutting-edge types and those (like myself) with more
time than money. Today it is rapidly becoming a commercial success. In
fact there are several commercial niches in which it is so superior to
its "competition" that it is already becoming a standard. But should you
switch? Here are my current thoughts on the matter.

If you are a hobbyist, hacker or power user, Linux is definitely for
you. Why? Because of its stability, its support for real multi-tasking,
its toolkit philosophy, its freely redistributable source code, and its
culture. Programmers (especially systems programmers) will find its
integrated and powerful development environment very alluring (in
particular, the X Window System is a much better development environment
than that offered by Messy$oft Windows). Anyone needing a multi-user or
network solution will find Linux attractive. Finally Linux offers better
facilities (and speed!) for connecting live to the Internet than the
single-user OSs common on PCs. I can only identify a few groups of users
who might not benefit from Linux's superior features. First, those
businesses who have complex mission-critical needs which might cost too
much to port to Linux (NB, this could be a sign of short-sighted
planning - such a business should carefully look at their long term
needs). Secondly, those users who have invested so much time and money
in their current systems that switching would be prohibitively expensive
in terms of training. Finally, users who are enamored by the "beauty" of
such corporate offerings as Word or Excel may find the Linux equivalents
less appealing. Linux does offer a very powerful and free typesetting
system, LaTeX2e. Although this is more powerful than any word
processor, it takes longer to learn. The AUIS system comes with a word
processor, EZ, but I have not seen an adequate review of it. Of course,
such a user could reboot to DOS, MS Windows, OS/2, or Windows NT to do
the one or two tasks for which they have not found adequate Linux
replacements.