2002 09 05

                    LINUX NEWS
           September 5, 2002 - Issue 97


1) Sean’s Notes

2) Linux News

Verisign in Hot Water
Doc Searls Reviews Gnomedex
Dell To Build Cluster
HP Sets EOL Date for PA-RISC, Alpha

3) Linux Resources

Dual Booting XP and Linux
Mozilla Laziness
Load Balancing With LVS
Automate Installs With Kickstart
The SCSI System in Action

4) App o’ the Week

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1) Sean's Notes

Now where did I put that file?

That's a question I've asked myself many times.  There's another
version of that question, namely:

Now where did he put that file?

The latter question is often asked when the file name is
"fix_database", the database is down, and the person referred to
as "he" is unavailable (or asking himself the first question).
The Unix filesystem is big, and with hard drive sizes ever
increasing, odds are you're going to misplace a file every so
often.  Fear not!  There are some utilities out there that can
help you find that lost file and save the day.

The first command is "which".  The purpose of this command is to
tell you the full path to the command you type.  Thus:

\# which sendmail

lets me know that if I type "sendmail", then "/usr/bin/sendmail"
will be executed.  If it turns out to be an alias, it'll let you
know that too:

\# which ls
alias ls='ls --color=tty'

The problem with "which" is that it only searches $PATH.  If
/usr/sbin wasn't in my path, it would have said:

\# which sendmail
/usr/bin/which: no sendmail in

So, a helpful command, but not always the answer.

The next one is "locate".  Every night, your system should run a
command called "updatedb" which traverses your filesystem and
stores the location of every file.  When you type "locate foo",
it searches through this database for "foo".  Note, it's a
partial match, so it'll match:


More caveats -- the index is only updated nightly.  If, for some
reason, the index doesn't run, your database won't be updated
(if it goes for longer than a week, you'll get a warning when
you run locate).  If the file was created after updatedb was
run, you won't find it either.

Later versions of the locate package actually use "slocate",
which is a secure version.  It used to be that anyone could look
at the whole database, so you could see the contents of people's
directories even if permissions denied it (since updatedb
usually ran as root).  slocate keeps track of permissions, so
you only see files you normally could.

\# locate fix_database

Well, that's where he stored it.

If locate doesn't turn it up, or you want to be really flexible,
"find" is what you want.  Find traverses the filesystem every
time you run it, so there is a penalty associated with running
it.  The general form of the command is:

find starting_points options


find / -name fix_database.pl

...will start at the root directory, and find a file with the
name "fix_database.pl" (note it's not partial match).  Since
you think it'll probably be in /usr or /home, you can give
that hint:

find /usr /home -name fix_database.pl

But maybe it wasn't "fix_database.pl".  It started with fix,
and was a perl script...

find /usr /home -name fix\*.pl

Note that I used \* instead of *.  That was because I'd be
typing it at the shell prompt, and I wanted to pass "*" to find,
and not have the shell try to expand the wildcard before passing
to find.  The use of the backslash is called "escaping", or
"protecting from the shell".

Find is also a very versatile command.  You can return files
owned by a certain person, or that were accessed or modified
between certain periods of time, or that have a certain size
range.  It's commonly used in cron to clean up temporary
directories.  For example, if you wanted to find all the "core"
files in /home that were a month old:

find /home -name core -atime +30

or, even have it delete them:

find /home -name core -atime +30 -exec rm {} \;

(note the ; must also be protected from the shell)

So, between "find", "which", and "locate", you should be able to
find the file you're looking for!

Long live the Penguin,


2) Linux News

Verisign in Hot Water
Everyone's favourite domain registrar *cough*not*cough* is
in trouble because their customer information is not up to date.
People like "Toto", living on "Yellow Brick Road" are able to
register domains, and ICANN doesn't like it.


Doc Searls Reviews Gnomedex
Gnomedex was just the other week, and the senior editor
of Linux Journal gave his review of the event.


Dell To Build Cluster
Dell is getting into the cluster market, building a 2,000 node
cluster to help the University at Buffalo with their scientific
research.  At 5.6 terraflops, it'll end up on the top 500 most
powerful computers in the wold.


HP Sets EOL Date for PA-RISC, Alpha

Now that HP owns both the PA-RISC and Alpha lines of processors, they've
set the End of Life dates to be the same.  No news on what will happen
after that, though.


3) Linux Resources

Dual Booting XP and Linux

Getting your regular Windows OS and Linux to coexist on one
machine can be a chore. If you really want this kind of
punishment, here's the page for you.


Mozilla Laziness

My brother showed me this trick with Mozilla that you can use to
create shortcuts to almost anything. For example, if I wanted to
do a google search for "linux", I could type "gg linux" in the
URL bar. Here's a page showing how this time-saving feature can
be implemented.


Load Balancing With LVS

The Linux Virtual Server project is often used to front end a
web server farm so that the load gets spread out over the
cluster, and so a downed machine doesn't cause service to be
affected. This article shows another use, namely load balancing
X-Windows sessions across a farm of HP-UX machines.


Automate Installs With Kickstart

Features like this are why I love Red Hat. Kickstart lets you
script an install of Red Hat, such that you can boot from a
single floppy or CD and install a box (hands free) over the
network. An old friend, njcajun, has put together a great
article on getting this software up and running.


The SCSI System in Action

SCSI, as it pertains to the kernel, is implemented as a series
of smaller parts, each of which serves a distinct function. This
article unravels the whole thing; it's very informative,
especially if you've wrestled with SCSI before.


4) App o' the Week

802.1x is an authentication protocol used on both wireless and
wired networks. Its purpose is to only allow authorized people
on the network, and Cisco even uses it to assign predefined
VLANs to users. This is a Linux implementation of the client.


(C) 2002 BrainBuzz.com, Inc. All Rights Reserved.

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