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                        LINUX NEWS
            RESOURCES & LINKS FROM BRAINBUZZ.COM
                  Thursday, April 12, 2001
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TABLE OF CONTENTS
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1) Sean's Notes

2) Linux News

	Slashdot Interviews Bob Young
	Linux PDA
	W32.Winux a Sign of Things to Come?
	New Digital Internet/TV has "Linux inside"

3) Linux Resources

	Clean up /tmp the Safe Way
	A First Look at Linux Clustering
	GIMP PERL Scripting
	Free Chapters on mod_perl
	Linux for Windows Users

4) App o' the week


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1) Sean's Notes
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The syslogd daemon is one of the more important programs that
is installed on a Unix box.  Its job, like the name implies,
is to log all the system messages.  Without the benefit of
syslog, the administrator is blind to what is going on with
the other daemons.  It is somewhat like the NT Event Viewer,
except that in traditional Unix fashion, is very configurable.

If you're familiar with the NT Event Log, you'll know that
you get a lot of messages sent into one of three different
logs (System, Security, and Application if memory serves).
Syslog lets you specify virtually unlimited different logs,
and gives you the power to choose what goes into them.

To do this we introduce two attributes of a log entry,
namely the facility and the priority (or severity).

The facility of the message tells us what type of
application the message came from.  auth, authpriv, cron,
daemon, kern, lpr, mail, news, syslog, user, uucp, ftp, and
local0-local7 are the available ones.  auth and authpriv
are security-related messages, with authpriv being used for
things that should be kept private.  The other ones are
self-explanatory, such as kern for kernel messages, ftp for
ftp messages, etc.  local0 through local7 allow systems not
covered by the above to be handled. For example, Cisco
devices default to local7.

The priority field lets you differentiate between debugging
messages and very important ones.  In terms of ascending
severity, you've got debug, info, notice, warning, err,
crit, alert, and emerg.

So, each message has both a facility and a priority.
Sendmail may log notification of handling an email to
mail.info, and errors such as insufficient disk space to
mail.err.

With the classification system in mind, it is up to the
administrator to decide what messages are important, and
where they should be logged.  Most distributions of Linux
have a pretty sane way of doing it, which serves as a basis
for further tweaking.  This is all controlled in
/etc/syslog.conf.  Generally, one line per file is the safe
way to do it (some versions of syslogd support some extended
syntax, which you should stay away from for portability
reasons).  Each line starts off with a list of the facility/
priority combinations, and the name of a logfile.  These are
separated by tabs.  (In practice, the Linux syslogd accepts
spaces too, but the Solaris one is very picky about
requiring tabs).

When you specify a priority, all higher priorities are
implied by default. This means if you select mail.info,
you're going to get mail.info all the way up to mail.emerg,
unless you explicitly say mail.=info.  The values of * and
none refer to everything and nothing respectively.  So, if
you wanted to log all the kernel messages to /var/log/kernel
you would have:

kern.*		/var/log/kernel

and if you wanted all the info messages except for mail in
/var/log/info:

*.info;mail.none		/var/log/info

Looking at the default syslog.conf is helpful.  Here, the
definition of the messages file, which is usually a good
place to find general messages about anything:

*.info;mail.none;authpriv.none		/var/log/messages

This grabs any messages with a priority of info or above,
unless they are from the mail or authpriv facility.  Later
on you'll see definitions for authpriv.* and mail.* to split
those off unto themselves.

Anything that isn't caught in the config file gets dropped.
Any changes to the file require that you restart the syslogd
daemon.  Furthermore, syslogd will not create the logfile,
you have to use the touch command to create it yourself.

You can test your rules with the "logger" command.  This
same command is also great for shell scripts to provide
status via syslog.

logger -p kern.info "Hey!"

--will write "Hey!" to kern.info.

The syslog system is very powerful, and allows you to
take control over what you log.  Since the back end
communication works on sockets and files, unprivileged
processes can safely write private messages.  The man pages
for both syslog.conf, syslogd, and logger will show you the
other options available, such as having all your machines
log to one central machine for security and ease of
administration.


Long live the Penguin,

Sean
mailto:swalberg@brainbuzz.com

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2) Linux News
===========================================================

-----------------------------
Slashdot Interviews Bob Young
-----------------------------
Bob Young, Chairman of Red Hat software, gave his answer to
some questions posed by Slashdot readers. Among them are his
take on Linux's future, and some pretty harsh criticism about
recent comments made by Open Source opponents.

http://slashdot.org/article.pl?sid
/04/11/1555216


---------
Linux PDA
---------
The Agenda VR3 is the first commercially released PDA that
runs Linux. Brainbuzz user mokjason gives some thoughts,
links, and the start of a discussion.

http://boards.brainbuzz.com/boards/vbm.asp?rpg=1&wpg=1&sb=0&m'5587


-----------------------------------
W32.Winux a Sign of Things to Come?
-----------------------------------
An announcement earlier in the month about a virus that is
supposed to be able to infect both Windows and Linux computers
came as quite a surprise to me. Though at the moment a low
risk, this article asks the question, "What Next?"

http://www.networkweek.com/wire/story/TWB20010402S0004


------------------------------------------
New digital Internet/TV has "Linux inside"
------------------------------------------
Embedded Linux devices may soon be making their way into homes
by way of televisions. This TV offers Internet functionality,
not to mention some sophisticated systems on the regular TV
programming. In a market where price is paramount, the maker
was able to drop the per unit cost by using Free software.

http://www.zdnet.com/zdnn/stories/news/0,4586,2694183,00.html


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3) Linux Resources
===========================================================

--------------------------
Clean up /tmp the Safe Way
--------------------------
Automatically getting rid of temporary files may seem like
an easy task, but if done improperly can cause problems.
Most often, you may be working on files that other people
can control, which requires some care. This article goes
through the simple cases, and then into some more secure and
correct ways of dealing with /tmp.

http://www.linuxgazette.com/issue18/tmp.html


--------------------------------
A First Look at Linux Clustering
--------------------------------
Most people are familiar with the concept of a Beowulf
cluster, which has been popularized lately by companies
like Shell. Have you ever wondered about the details behind
such a beast? Are there other ways to accomplish the same
thing? This article tries to answer those questions, and
the reader comments at the end round it out.

http://www.linux.com/newsitem.phtml?sid“&aid019


-------------------
GIMP PERL Scripting
-------------------
I'm a big fan of the GNU Image Manipulation Tool. The wide
range of plugins available is astounding, plus it's really
easy to write your own. I've always wondered how to use the
Gimp perl module so that I could control it from Perl
(rather than learning Scheme). Alex Harford, an author and
fellow Canadian, wrote an excellent tutorial on the Gimp
perl module.

http://www.dowco.com/~alexh/perl.html


-------------------------
Free Chapters on mod_perl
-------------------------
mod_perl is an apache module that embeds a perl interpreter
within the web server itself to enhance performance. This
site has some sample chapters from the O'Reilly book on
writing perl apache modules, covering topics such as the
Apache::Registry module (to replace CGI), and writing
authentication and authorization modules.

http://www.modperl.com/book/chapters/


-----------------------
Linux for Windows Users
-----------------------
For those not wanting an in-depth technical discussion of
how to migrate, this article takes a high level view of the
differences and similarities in the GUIs. There are lots of
screen shots presented together that highlight that Linux
can be just as easy to use as Windows.

http://mozillaquest.com/Linux4Windows/Linux4Windows01/Linux4Windows
_01_01_St
ory-01.html


===========================================================
4) App o' the week
===========================================================
The first time I tried this out, I was hooked. PHPNuke is a
PHP web site system that allows you to update news articles
easily, host forums, FAQs, and downloads. It is all done
within a theme structure, so you can easily change the look
and feel of your site without having to know much PHP.
MandrakeSoft, the makers of the Mandrake Linux distribution
hired the author of this on a full time basis, ensuring that
PHPNuke will be around for the long haul.

http://www.phpnuke.org

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(C) 2001 BrainBuzz.com. All Rights Reserved.
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