...making Linux just a little more fun!

February 2006 (#123):


The Mailbag

HELP WANTED : Article Ideas
Submit comments about articles, or articles themselves (after reading our guidelines) to The Editors of Linux Gazette, and technical answers and tips about Linux to The Answer Gang.

Running Apache and AOLServer Together

Sun, 15 Jan 2006 18:25:11 +0000
Martin O'Sullivan (martin_osullivan from vodafone.ie)
Hi Jimmy
this sounds like something you would know the answer to.

Short answer, no. I'm cc:ing the Answer Gang -- someone might have done something similarly insane once :)

Running Apache and AOLServer Together

I want to do the following
Run two web sites off one server using two different http daemons

1 Apache listening on port 80
2 AOLServer listening on port 8080

The apache server will be accessed by using url http://s1.com
The AOLServer will be accessed by using url http://s2.com

The Names s1.com and s2.com are pointing at the same IP Address.

If apache gets a request for www.s1.com it deals with it.
If apache gets a request for www.s2.com it says not for me and Reads its proxy entry, which tells it go to AOLServer on port 8080

The Proxy stuff is working on apache.

Problem apache won't do this for me (I not sure if this scenario is even possible)
My entry in the apache conf file is as follows. 

ProxyRequests Off
<Proxy *>
    Order deny,allow
    Allow from all
</Proxy>
ProxyPass /s1.com http://s1.com:80/
ProxyPass /s2.com http://s2.com:8080/

Why such a ridiculous set-up (Very long story)
I know about apache Virtual Hosting option but can't use it in this situation. Can anyone help? http://forums.openhosting.com/viewtopic.php?t=105

It has been posted to the following forum http://www.openacs.org/forums/message-view?message%5fid=361728 http://forums.openhosting.com/viewtopic.php?t=105

Martin O'Sullivan web: http://martinri.freeshell.org E-mail martin_osullivan@vodafone.ie

Ultra-cool

Tue, 3 Jan 2006 05:55:54 -0500
Benjamin A. Okopnik (LG Editor)
[Heather] Encountering anything that you find is such a cool Thing To Have (if you're a linux sort) that you just wish you had three of it for your birthday? Actually, hearing that somebody not only got some new at-the-fringe-of-linuxing thing like this, and how they got to using it, could indeed Make Linux Just A Little More Fun - check out our Author's FAQ and then send article ideas to articles@ where our articles team can take a look.

In the "not (yet) Linux" category: this is the cool gadget of the year - tablet computing on paper. I see some very, very interesting possibilities in the future for this thing if it gets into the mainstream.

http://www.mobilityguru.com/2005/12/19/pentop_computing_is_more_than_a_kids http://www.flypentop.com

* Ben Okopnik

[Heather] From the awwwwwwwwwwwwwwwwwwwwww :) :) :) department:

"This project provides 'executables' that enable you to make your own soft-toy Linux penguin. To put it straight: You can find sewing patterns and a community to sew your own soft toy or stuffed Linux Tux penguin here."

http://www.free-penguin.org

Saw this here: http://www.tenslashsix.com/?p=102 -- scroll down to the picture of the gadget sitting beside a beer bottle -- another USB powered mini-server.

It's a Blackdog (http://www.projectblackdog.com), and uses the Linux-USB Gadget stuff (http://www.linux-usb.org/gadget) to do Ethernet over USB and USB Mass Storage. It also comes with XMing (http://freedesktop.org/wiki/Xming) so you can use X from Windows.

[Heather] Anybody wanna try putting a USB gadget-computer inside of Tux and then using one of those odd pens as a real data entry tool to take good bits back to your penguin? Glory awaits!

public ntp time server clusters

Mon, 23 Jan 2006 11:56:41 -0500
Suramya Tomar (The LG Answer Gang)

Hi Everyone,

Found the following during my one of my aimless wandering sessions on the web and thought that it was interesting enough to share with you all.

http://www.pool.ntp.org: Public ntp time server for everyone

Quote from Site:

...............

The pool.ntp.org project is a big virtual cluster of timeservers striving to provide reliable easy to use NTP service for millions of clients without putting a strain on the big popular timeservers.

...............

I would have shared my ntp server if I was running one and since one of the requirements is that your IP has to be a static IP I can't use my home system to run one and share it (Its IP hasn't changed in a while but its not static :( ). But if any of you nice people feel like sharing then please feel free to join the cluster. I think its a worthwhile project.

Well this is all for now. Hope you found this useful.

Thanks,
Suramya

tput cwin question

Sun, 5 Feb 2006 22:12:36 -0700
Mike Wright (mike.wright from mail.com)

Hi, I have been trying to figure out exactly what the 'cwin' option to the tput command really means.

What I'm hoping that it will let me do is to create another window in the current terminal using a section of the screen to output listings from different commands that will be executed from numbered menu options. And if the output is several screens then it can be presented a few lines at a time to the user with the option to page down through the many screens of output while not disturbing the menu options at the top of the screen nor the status bars at the bottom of the screen.

If you could provide an example of how to use the 'cwin' option and 'wingo' option to the tput command I would be so happy. And I would appreciate it very much. I've read all of the documentation that I have been able to find and either the documentation for these two options doesn't exist or nobody uses these two options.

Any help that you can provide with this will be greatly appreciated.

Here is an example of how the screen would look if I could do what I wanted to do. 

Please make your selection:



1. List all VxVM Volumes

2. List all VxVM Disk Groups

3. List all VxVM Disks

4. Quit


Output of command selection # 2
******************************************************************************

*
datadg
*

*
syslogsdg
*

*
inventorydg1
*

*
inventorydg2
*

*
inventorydg3
*

* [ Press the space bar to page down ]                                        *

******************************************************************************


Current Time: 3:19 AM   Hostname: server1



F1 DiskSuite                     F2 VxVM                        F3 Exit
[Heather] Your kindly editor suspects the borders of this screen have been mangled by our mailreaders, nonetheless ... it's genuinely interesting stuff. I recall that a long while back the text form of YaST (SuSE's installer and admin tool) used tput, but I don't know if this is still the case.
If anyone would like to tackle an article demystifying tput - or even modern curses programming, for that matter - drop us a line!

Thank you.

Sincerely,

Stale Ruffles

GENERAL MAIL

reader comments to articles

Tue, 23 Jan 2006 23:38:07 -0500
Edgar_Howell (Edgar_Howell from web.de)

Greetings,

Once again a couple of readers have responded with very useful comments, well worth making available to other readers.

1. CUPS Password

A reader who didn't want public mention let me know that the following command takes care of my problem with the CUPS password: 

   lppasswd -a root -g sys

He suggests entering root's password, when asked.

2. Installation Software on External Media

And Dennis Kibbe of the Phoenix Linux Users Group pointed out that for an additional $10 Dell will in fact provide the WinXP Installation CD.

To be honest I don't know whether that isn't an option on this side of the pond or I just didn't know about it. Windows awareness is not one of my strengths.

Ignoring philosophical and ethical considerations, that certainly is a far more pragmatic approach and I almost certainly would have coughed up the $10.

3. Installation Software, part 2

Recently a colleague gave me an article dealing with the problem of installation media and the suggestion in it might be of interest to anyone in a similar situation, although how long this might remain valid is anyone's guess. Note that this addresses the operating system only, not any other software the manufacturer of the hardware might have included.

Basically the premise is that all that is needed is the branch "i386" from either some partition on the hard drive or a "recovery CD". Inside this directory is a DOS executable, "WINNT.EXE", that installs the operating system from the other contents of that directory.

Aparently there are complications in the boot process such that one needs a particular boot program, available on the CDs with earlier versions, which I of course don't have, so no way to make a bootable installation medium.

It was also mentioned that this directory should be over 420 MB in size and contain close to 6000 files. What I found was almost 800 MB and that clearly wouldn't fit on a CD. So I tar'd it together and pushed it over the network onto another machine.

There I blew away everything under '98 that didn't look like DOS, changed into the directory "i386" and then started the installer, WINNT.EXE. This produced a DOS-style screen with the heading "Windows XP Setup" and a question about the installation directory, which I left as it was. Another screen or two later it complained about not finding 593 MB of free disk space and broke off the installation. But that was really all I wanted to see -- I have no use for this software anywhere else.

I don't wish on anyone the headache of trying to teach Windows some manners. But should co-existence become necessary for you, I hope this information might be of help for however long that situation may last. And best wishes for a quick recovery.

*** DISCLAIMER ***

This procedure may be illegal where you live!

Here, in Germany, many years ago the courts decided that there is no inherent relation between software and hardware and that one can sell a used software license as legitimately as used hardware. This requires, of course, retaining no copies of the software.

From this it seems reasonably to follow that one may move any software from any hardware to any other, as long as at no time the number of valid licenses is exceeded. But prudent data processing practice dictates at least one back-up copy of all data and software. However, since over-riding copy-protection and encryption is a violation of the law here, it almost certainly is illegal to do this with software so protected.

I'm not a lawyer. You need to know the rules on your own turf.

ech

KUDOS - 1st TIME READER, IMPRESSED!

Fri, 3 Feb 2006 05:07:29 -0600
rion (rion from mchsi.com)

for the text, your pages d/l quick! :) most "help sites" sugar too much..

i found: issue76/tag/9.html ;p sigkill 13 & the 'local' runs only in a func.. i remember reading that man, earlier

..hmm latenight bragging time!

[Heather] Some not linuxy things, snipped.

moreover.. http://linuxgazette.net/issue60/issue60.html#tag/10 is down.. :( ..i had a question bout gpm & blocks of solid color invading my screen..!!! well, i ctrl-key it, but it makes.. hulk smash.. :sigh:

:Turns the channel:

i think ill go grab some flashgames or something.. later!

chris

[Heather] Thanks Chris, for taking a moment to write! Have fun gaming!

Slashdotted!

Fri, 06 Jan 2006 22:35:16 +0000
Jimmy O'Regan (The LG Answer Gang)

http://linux.slashdot.org/linux/06/01/06/1539235.shtml?tid=198&tid=106

"From the some-of-this-content-may-be-inappropriate-for-young-readers dept."

Yes, "Benchmarking Linux Filesystems Part II" got us back onto Slashdot, to a page almost entirely filled with comments bitching about how the benchmarks were done. (But, it wouldn't be Slashdot...)

Re: "Stepper motor driver for your Linux Computer" (Sreejith

Sat, 14 Jan 2006 09:04:43 -0500
Jan-Benedict Glaw (jbglaw from lug-owl.de)
Question by The Answer Gang , sreejithsmadhavan@yahoo.com (tag from lists.linuxgazette.net)

[Ben] Hi, Jan-Benedict!

I'm going to CC this to the author and The Answer Gang

Hi!

I've read that article (http://linuxgazette.net/122/sreejith.html) and I wonder who reviewed that one.

[Ben] Well, David S. Richardson and I both proofed it for grammatical and stylistic errors, but unfortunately, I don't think we have anyone on the proofing team who can do good technical review for C: my own C-relevant experience, for example, was back in the days of _DOS._ Want to volunteer? :)

Uhm, yes, I think so.

[Heather] Hooray!

[Ben] Great! I'll contact you off-list, then.

The wiring diagrams and timing diagrams for a stepper motor are indeed correct and helpful, but the module's source code isn't, for numerous reasons. Even the minimalistic module is plain wrong--nowadays.

Let's look at the source:

* "#define MODULE"

You realized that this is 2.2.x material? We're at 2.6.x right now!

[Ben] I note that he did specify that this was for a 2.4.24 kernel. That's why, when I tried to compile the code and it failed (I'm at 2.6.13.3, myself), I let it go.

* "#include <asm/uaccess.h>"

We're driving a 8255, that's not rocket science. There's absolutely no need to write just another driver for a normal PC parport: there is one already. To be exact, there's a complete framework to drive anything that has a DB-25 parport connector outside at the box, irrelevant by what kind of chip this is driven (thing SGI machines, Amigas, PowerPC, ...). This module would only work on a PeeCee, nothing else.

* static int pattern[2][8][8]

...isn't even initialized fully. Also, some macros could probably help making all the numbers readable...

* MOD_INC_USE_COUNT / MOD_DEC_USE_COUNT Again, this is 2.2.x material and should be dead since long ago.

* Port access to the 8255

This module doesn't register its I/O space, so it could fuck up a already loaded parport driver.

* Last but not least: it doesn't even work! ...because it doesn't actually access the hardware at all!

[Heather] As noted later, it does work for Sreejith, for a limited case, which alas, you readers probably don't have.

If this had been published some 6 years ago, it would probably fall under the "this is a quick'n'dirty hack" rule, but today, I guess something like that shouldn't be published at all, because it aims towards quite a wrong direction. Not to imagine that anybody might think this is good programming style...

Well... if you can show a better way to do this, I'm sure that our readers would appreciate it - and we'd be glad to publish it as a followup to the article. Otherwise, I don't know that there's anything we can do to improve the situation.

Regards,
* Ben Okopnik *

[jra] Publish his response, and put a tag pointing to it on the original article?

[thomas] Well, yes. This is something we've always done. :)

[Ben] Yeah, but that's not a fix - just a problem description. I'm trying for both. Ya know: LG, all about reader participation... :)

[jra] True. But even a total failure can always serve as a bad example. :-)

I've got some code around to access the ppdev API. With this, the module isn't needed at all and thus the resulting application only consists of simple and portable userland code.

[Ben] I think that, even though the implementation is broken, the underlying premise of Sreejith's article is valid; our readers would, in my opinion, find it interesting to see a simple introduction on accessing hardware by writing a module. Do you think that the article is salvageable as it is (i.e., is it possible to make the code work - regardless of whether another tool for it exists or not), or is it just broken from the start?

@Sreejith: http://lug-owl.de/~jbglaw/software/steckdose/steckdose.c is some code using the ppdev API to access the parport lines. Maybe you want to have a look at that? I'd try to write some code driving a stepper motor in full-step mode, but since I don't have one handy right now, you'd need to test that.

The code mentioned above drives a shift register connected to a parport (It is driving some home-made hardware; at the parallel outputs of the shift register, there are relays switching my computers on and off. That way I don't need to go down into the cellar to switch a machine on or off :-)

It is quite simple: 

for (each bit to be pushed serially into the shift register) {
	put_one_bit_on_the_serial-in_data_line();
	rise_clock_line();
	lower_clock_line();
}
move_shift-state_into_output_latches();

Because shift registers output their falling-out bit at the end, this can be fed into the next shift register. That way, I can cascade a dozens of these chips to control 100 lines.

Maybe something like that could even be presented as an article, but to date I haven't production-level PCBs, but only hand-made ones.

MfG, JBG

Jan-Benedict Glaw jbglaw@lug-owl.de

[Heather] Ben gets an answer from the article author, with a bit of after-the-fact concern about the original reasoning, and maybe a bit of self-abashment about accepting it too close to deadline.

On Wed, Jan 18, 2006 at 02:54:43AM -0800, Sreejith Nair wrote:

Hello sir, I noticed those serious mistakes in my article.

[Ben] I would have appreciated it if you had said something about them when submitting it rather than presenting them as useful code, then.

Actually i did this experiment as my Mini project in the 4th semester of my B Tech course(June 2003). At that time i was using 2.2 kernel and i learned the basics in the same. But now i am working with Fedora core 1 (2.4.22 -1.2115.nptl). So what happened is, i just modified the code for the new kernel and rectified the compilation errors. And now i see....its a mixture of 2.2 and 2.4 things.

But it is a working code. I can control my toy stepper motor with this code.

[Ben] Unfortunately, it doesn't compile for me - even after I've taken out the hard-coded kernel location in the INCLUDE line: 

ben@Fenrir:/tmp$ make
cc -O2 -DMODULE -D__KERNEL__ -W -Wall -I/usr/src/linux/include   -c -o stepper.o stepper.c
stepper.c:1:1: warning: "MODULE" redefined
<command line>:1:1: warning: this is the location of the previous definition
In file included from /usr/src/linux/include/linux/bitops.h:77,
                 from /usr/src/linux/include/linux/thread_info.h:20,
                 from /usr/src/linux/include/linux/spinlock.h:12,
                 from /usr/src/linux/include/linux/capability.h:45,
                 from /usr/src/linux/include/linux/sched.h:7,
                 from /usr/src/linux/include/linux/module.h:10,
                 from stepper.c:3:
/usr/src/linux/include/asm/bitops.h: In function 'find_first_bit':
/usr/src/linux/include/asm/bitops.h:339: warning: comparison between signed and unsigned

[ ~150 similar lines elided ]

make: *** [stepper.o] Error 1

For testing, i was just printing the hex value to the console instead of writing to parallel port. For controlling stepper motor, the -printf("%d\n",pattern[i][j] [k]); - statement should be replaced with - outb(pattern[i][j][k],LPT_BASE); . Anyway this is a serious mistake and I deeply regret and apologize for that.

[Ben] Well, we'll let our readers know not to expect this code to work, then; publishing this exchange should do it. Fortunately, every cloud has a silver lining: Jan-Benedict Glaw, who noticed the problem initially, has agreed to review future C code for us so that this kind of thing doesn't happen again.

Nowadays, because of my workload, i am not able to explore "The Linux World" that MUCH!... My intention was not to develop a professional stepper motor driver as i know that there already exists a parallel port driver in Linux. I just wanted to share the basics of device driver coding through an example.

[Ben] Sreejith, may I ask why you wrote this article in the first place?

Actually, never mind: the above question is best treated as rhetorical. Instead, I'll just pretend that I'm having this exchange with $AVERAGE_AUTHOR - a fellow who just wrote an article that failed in the same way as yours did, and from whom I got the same above excuse when I asked him about it (and to whom, unbeknownst to him, I've slipped a bunch of truth serum in his morning tea.)

Does this scenario look familiar?

The problem is that there's a "best effort" clause hidden in doing any kind of work for the Open Source community. The coin of Open Source is respect - and when you put out less than your best effort, then that coin might not only be a bit slow in coming, but might not appear at all - and will disappear instantly when that respect is discovered to be unearned. Note that I didn't say "will disappear when a mistake is discovered" - everyone makes mistakes. The deciding factor is in how you handle having made the mistake: making excuses such as "my intention was not to develop a professional [application]" destroys the last possibility of getting paid in that coin, whereas - for example - admitting the error honestly and taking a few minutes to produce working code that could be published as a corrective note the following month would have salvaged some of the credit.

The staff here at LG put out their best effort to edit, format, and publish the material that is submitted to us; I can guarantee you that all of it is hard work, but despite that, excuses like "well, it's not a professional publication" don't have much currency here.

[Heather] We've grown increasingly towards professional traits over the years, cover art and so on. But we've had a formal editor ever since Marjorie took over from John Fisk many years ago. Sometimes we fail to edit as professionally as we'd like - and sometimes what we are aiming for is a homey, at a real person's desk kind of feeling - and we do it for love of linux and not the money - but that shouldn't make the best effort a sad one.

[Ben] By that same exact token, we expect that our authors - especially those submitting code - have made their best effort to make sure that their code works in the current Linux environment, and have done at least some minimal testing. Perhaps that assumption was unwarranted in this case, for which I personally apologize to our readers (since I was the one who accepted the article for publication); however, that is our default expectation. I don't see how ANY interaction based on respect can imply anything else.

Just as a relevant technical note, by the way: the 2.6 kernel has been available for download since 17-Dec-2003 (according to the timestamp of http://www.kernel.org/pub/linux/kernel/v2.6/linux-2.6.0.tar.bz2) - I see no reason why an article directed at kernel-related coding would cover the 2.4 kernel as its primary target. 

* Ben Okopnik * Editor-in-Chief, Linux Gazette * http://linuxgazette.net *
GAZETTE MATTERS

Our Editor In Chief is now married!

Sat, 28 Jan 2006 15:17:00 -0800
Heather Stern (The Answer Gang's Editor Gal)

I'm very pleased to announce that our Editor In Chief, Ben Okopnik, has married his dear Kat.

The wedding was delightful (give or take getting lost on the way there), the music was fun, the food was fine, and the nearby outdoor gardens were pretty, too. Those of us present who did not immediately have to leave again joined the happy pair afterwards at a nearby restaurant whose chef is, in my not so humble opinion, rightly famous.

It was great. Go see the Back Page for a picture of the happy pair.

Rumors that his biggest client paid for the honeymoon turn out to be halfway well founded in that they invited him to go for pay to the kind of place that he and his bride would have been delighted to go to anyway. Smiles from the universe are always appreciated :)

How to get linux gazette in pdf or ps format

Tue, 03 Jan 2006 17:49:18 +0530
Shirish Agarwal (shirishag75 from gmail.com)

Hi all,

I saw that one can get LG either as a single html or group of html pages, I would like to have them in a self-contained ps, pdf or even an openoffice document. The simple reason is that one can do this off-line more easily. I did try to get this answer from the various knowledge bases which u have mentioned on the site but wasn't able to get even close to that. Hope u can help here & maybe also update the same in the knowledge base for future. Thanx in advance.

Shirish Agarwal
Life is a dream Enjoy it!
Creative Commons, Attribution
Non-commercial, non-derivative

[Rick Moen] Well, I notice upon a quick search that you can use:
http://directory.fsf.org/print/misc/html2pdf.html

[K.-H.]
There is a little commandline tool named "html2ps" which will fetch e.g. the TWDT page and convert it into a ps file. for the current linuxgazette this would be:
html2ps -o test.ps -U http://linuxgazette.net/121/TWDT.html

-U is supposed to generate the colored background (e.g. code) but doesn't do it for me, and -D would generate DSC info so you can go back and forward.

Using ps2pdf you can convert it again into a pdf file.

Otherwise there is always the print-to-file in your browser which generates postscript as well (at least in Linux).

Hope that helps you along....

Talkback links

Sat, 14 Jan 2006 09:17:00 -0500
Benjamin A. Okopnik (LG Editor)
with a few replies by The Answer Gang (tag from lists.linuxgazette.net)

Hey, everyone:

What do you think of the idea of "Talkback" links at the top of each article? Perhaps something like this: 

<a href="mailto:tag@lists.linuxgazette.net?subject='Talkback:<article_name>'">
Discuss this article with The Answer Gang
</a>

It works on several different levels, I think.

[Thomas] This was trialed for a while when LG was at SSC. It worked relatively well for some articles, except that it tended to be abused by some (c.f. my posting to TAG some years ago about someone wanting to know how to change the oil in their car.)

.

[Rick] How do you change the oil in your car? ;->

I think it's worth trying, Ben.

Yeah, some clueless people might use it to piggyback their own question into TAG, but they can be pointed right back out (i.e., 'read "Asking Questions of The Answer Gang" at <http://linuxgazette.net/tag/ask-the-gang.html>!'), and anyone wanting to comment on a specific article can do so easily.

Thoughts?

It wouldn't hurt to try, I suppose. What's the worst that could happen? At the moment, any specific article feedback is often forwarded to TAG -- since a lot of it gets sent to the author directly. So yeah... try it.

-- Thomas Adam

[Pedro Fraile, one of the Answer Gang]

"Talkback" content at the old site did not go to the TAG list, and so was lost when the site was transformed. With Ben's suggestion, any useful comment or correction would appear in next month's issue and would so be preserved.

Yes, I like it.

[Heather] Do you like it too? Let us know! Ok, so it may be a kind of skewed sample, only people who bother to read all the way to the bottom of the mailbag are going to answer. But it's a fair question - will it be more fun to have a fast link at the top? That's what it's all about after all - Making Linux Just A Little More Fun :)
This page edited and maintained by the Editors of Linux Gazette
HTML script maintained by Heather Stern of Starshine Technical Services, http://www.starshine.org/

Talkback: Discuss this article with The Answer Gang

Published in Issue 123 of Linux Gazette, February 2006

Re-compress your gzipp'ed files to bzip2 using a Bash script (HOWTO)

By Dave Bechtel

If you were incredibly lucky (like me), perhaps you received an external USB hard drive for Christmas. Or perhaps you have one lying around already, with plenty of free space. And perhaps you also read the recent Slashdot article about compression software and have lots of fairly sizable gzipped files laying about.

After reading the comments in that article, I was dismayed to learn that my favorite compression tool of choice (gzip) has no error-correction capabilities. While I deem it to be the best all-around for quick backups with a decent compression ratio, gzip will choke if it gets a data error on restore - and there's something to be said for data integrity.

So, having this nice shiny new USB external drive and some time on my hands, I wrote a Bash utility script to re-compress gzip files to bzip2, using the external drive. It takes an order of magnitude longer to compress, but at least I'll save some space and have a hope of recovering the compressed data if things go wrong... Right??

My particular external drive is a 120-gig that came factory-formatted as a single FAT32 partition. Now, any Linux guru worth their salt knows that this thing practically begs to be customized, since Fat32 has a 2GB(Linux) or 4GB(Windows) filesize limit - depending on who's writing to it.

So, I fired up my Knoppix HD install and repartitioned it. Nothing fancy, just good old fdisk.

Here's how it looks now:

$ fdisk -l /dev/sdb

Disk /dev/sdb: 255 heads, 63 sectors, 14593 cylinders
Units = cylinders of 16065 * 512 bytes

   Device Boot    Start       End    Blocks   Id  System
/dev/sdb1   *         1         1      8032   83  Linux
/dev/sdb2             2     14593 117210240    f  Win95 Ext'd (LBA)
/dev/sdb5             2        18    136552   82  Linux swap
/dev/sdb6            19      4999  40009882    c  Win95 FAT32 (LBA)
/dev/sdb7          5000      5622   5004247   83  Linux
/dev/sdb8          5623     14593  72059557   83  Linux

(I did make a note of the fact that the factory-default was one big type "c", in case I needed to go back to that.)

Notice the 40GB Fat32 partition. In my other life (sssshhh!) I run Windows 2000 Professional - and was forcibly reminded that everything after Windows ME has a 32GB partition size limit for formatting Fat32. Note that the limitation is on formatting - not accessing - this is by design, and Microsoft has publically admitted it.

After going through several free Windows tools for formatting and repartitioning (and running into a brick wall), I eventually gave up on Windows 2000 formatting the thing. The vendor has a utility on their website to restore the drive to factory-default partitioning, but that doesn't really help my intended use of the drive. I could have formatted it in Windows 98, but that's no fun - and it would need a separate driver for the OS to recognize the drive.

So, rather than give up a perfectly usable 8GB, good old Linux to the rescue again: 

$ mkdosfs -F 32 -v -n wdfat40 /dev/sdb6

and reboot.

Presto! Windows 2000 recognizes the drive just fine now, and it passes all the chkdsk tests. And for all you dual-booters out there, a wonderful utility exists called Ext2IFS ( http://www.fs-driver.org/ ). This allows NT-based systems like Windows 2000 to access ext2/ext3 partitions just like a regular drive - read/write, so no need for NTFS!

The Linux partitions were formatted like so: 

mke2fs -j -c -m1 -v /dev/sdbX

Here are the /etc/fstab entries I created for the drive, BTW: 

/dev/sdb6  /mnt/wdfat40  auto
defaults,noauto,noatime,user,suid,noexec,uid=dave 0 0
/dev/sdb7  /mnt/wdlinux  ext3 defaults,noauto,noatime,rw 0 0
/dev/sdb8  /mnt/wdvast  ext3 defaults,noauto,noatime,rw 0 0

Note the "uid=dave" in that first line. That's so my non-root user account will have write access to the drive by default.

Now onto the good part - the "rezip" Bash script.

At first, I started out by writing a fairly basic script with a simple function call and manually-entered filenames. Then I sat down and took another look at it - and practically rewrote it from scratch, with some features that occurred to me after several test runs.

rezip Currently Features:

-- KNOWN BUG(s):

During the course of writing the script, I had hard-coded most of the defaults, such as the size of files to skip, the log file name, etc. These were eventually changed to be variables before the script was published for LG - so that you, the end-user, can have More Control (TM) over its actions. ;-)

I encourage everyone to READ THE SOURCE CODE before running rezip. You may find it handy to view it in an editor that colorizes or highlights executable syntax, such as ' mcedit ' or ' jstar '.

Comments, feature requests, bug reports, etc., are welcome.

( Don't forget to ' chmod +x rezip ' and put it somewhere in your $PATH - /usr/local/bin is suggested. )

Talkback: Discuss this article with The Answer Gang

[BIO]

Bio: Born in 1972, Dave Bechtel grew up programming in Basic with Apple ][e's, TI99 4/A, IBM PC (640K!) and a Tandy 1000SX, none of which actually had hard drives -- 360K floppy only. And we LIKED IT! ;-)

Eventually left BASIC behind, and moved on to programming in REXX and Bash.

Got interested in Linux around 1997. Started with Red Hat and went on to SuSE, tried several other distros and a *BSD or two, and has now settled on Knoppix/Debian/Ubuntu, in roughly that order. Currently living in Lake Zurich, IL.

Likes: Computers, motorcycles, Linux, reading and watching sci-fi (currently Star Trek TOS, Stargate, and Battlestar Galactica)


Copyright © 2006, Dave Bechtel. Released under the Open Publication license unless otherwise noted in the body of the article. Linux Gazette is not produced, sponsored, or endorsed by its prior host, SSC, Inc.

Published in Issue 123 of Linux Gazette, February 2006

uClinux on Blackfin BF533 STAMP - A DSP Linux Port

By Jesslyn Abdul Salam

Intel and Analog Devices Inc. (ADI) jointly developed the Micro Signal Architecture (MSA) core and introduced it in December of 2000. ADI's Blackfin processor functions as a DSP and a microcontroller. This device is currently used for multimedia applications.

This article provides an introduction to programming the BF533 STAMP board and is intended for readers with some experience in Linux as well as with embedded devices. It contains a basic description of using the board for embedded programming as I have done without any problem.

BF533 STAMP

The STAMP board features:

The BF533 STAMP runs uClinux - a Linux port for embedded devices. It has soft real-time capabilities, meaning that it cannot guarantee a specific interrupt or scheduler latency.

The STAMP board has been specifically designed to support the development and porting of open source uClinux applications and includes the full complement of memory along with serial and network interfaces. The STAMP uClinux Kernel Board Support Package (BSP) includes a CD with a recent copy of the open source development tools, the uClinux kernel, and the documentation. For more details visit http://blackfin.uclinux.org.

uClinux

The uClinux kernel provides a hardware abstraction layer. The uClinux Application Programming Interface (API) is identical for all processors which support uClinux, allowing code to be easily ported to a different processor core. When porting an application to a new platform, programmers only need to address the areas specific to a particular processor - normally, this means only the device drivers.

Getting Started

We have to note the following components of our development board:

The development workstation is essentially a Linux box which should have

There are two potential interconnections between the workstation and the target:

Connecting the Hardware

  1. Connect the serial port to your host computer from the STAMP board
  2. Connect the Ethernet cable to your network card of your Linux box ( use a straight cable with no cross connections )
  3. Start the terminal emulation program. Minicom is an example of such a program, and is included in most Linux distributions. At the bash prompt type the following command as root: 
    bash# minicom -m -s /dev/ttyS0

    From the configuration menu within Minicom, set the serial port connection to

    • 57600 baud
    • 8 data bits
    • Parity none
    • 1 stop bit
    • H/W flow control off

    Now Save the configuration and choose Exit.

  4. Connect the DC power cord and power up the board
  5. After the STAMP board powers up, you should see a U-boot start-up screen in your terminal window. At this stage, if you allow the boot timer to count down, the board will load the uClinux kernel from flash memory and boot it, finally resulting in a command prompt.

GNU/Linux tool chain for the Blackfin devices

Install the binutils and the GCC tools on your machine:

[ Note: 'rpm' is RedHat-specific. Use the appropriate package manager for your distribution to install the latest 'bfin-gcc' version; if your distribution does not have one, use the 'alien' utility to convert this RPM to your required format. -- Ben ] 

bash# rpm -ivh bfin-gcc-3.4-4.1.i386.rpm

You may not find the same version of GCC tools on the CD. I had to download the latest version since the one provided with CD did not contain the required tools (e.g., the C compiler for building programs on uClinux.) You may download the RPM from here. Or you can visit the Blackfin website to download the toolchain yourself.

In user mode, export the path for the tools:

bash# export PATH=/opt/uClinux/bfin-elf/bin:/opt/uClinux/bfin-uclinux/bin:$PATH

Installing the uClinux Kernel

  1. Copy the kernel source from the CD to your work directory
  2. Uncompress the Kernel source

    bash# bunzip2 uClinux-dist.tar.bz2
    tar -xvf uClinux-dist.tar
Now that the kernel is uncompressed in the work directory, you are ready to start building your own uClinux kernel for the Blackfin processor.

Simple 'Hello World' Application

Traditionally, development environments and programming languages have always begun with the 'Hello World' program; we'll follow the precedent.

Copy the following into a file called 'hello.c':

#include<stdio.h>

int main() {
	printf("Hello, Welcome to Blackfin uClinux!!\n");
	return 0;
}

The next step is to compile 'hello.c' on you host PC:

bash# bfin-uclinux-gcc -Wl,elf2flt hello.c -o hello

The resulting executable is named hello.

Note that the bfin-uclinux-gcc compiler is used; this compiler is used to compile programs that run on the uClinux operating system. It automatically links our program with the uClinux run time libraries, which in turn call the uClinux operating system when required ( for example ) to print to the console. The compiler collection for the Blackfin processor also includes another compiler, bfin-elf-gcc, which is used to compile the actual uClinux operating system and uses a different set of libraries. If you want to try porting other RTOSs to Blackfin, you will have to use bfin-elf-gcc.

Now we need to set up the Ethernet port on the Linux box; we'll set its IP address to 192.168.0.2. After booting the uClinux kernel on the STAMP board, you will have to configure its Ethernet interface as well; at the bash prompt of the STAMP, type the following:

root:~># ifconfig eth0 192.168.0.15 up

At this point, the Ethernet link should be up. We can use FTP to upload the 'hello' program from the host to the board. At the bash shell prompt of the linux workstation type the following:

bash# ftp 192.168.0.15

Give the username and password as root and uClinux. Send the 'hello' executable to the STAMP board.

Now modify the permissions and run:

root:~> chown 777 hello
root:~> ./hello
Hello, Welcome to Blackfin uClinux!!

Segmentation faults

The Blackfin processor does not have an MMU, and does not provide any memory protection for programs. This can be demonstrated with a simple program:

// test.c
int main ()
{
	int *p;
	*p=5;
}

Compile 'test.c' using our native C compiler. Try to run the resulting executable, and you'll end up with a segmentation fault.

Now, compile the program using 'bfin-uclinux-gcc' as I described above. Send the executable to the STAMP board using FTP, change the file permissions, and run it.

This time, it should run without a segmentation fault. Due to this, an unprivileged process can cause an address error, can corrupt kernel code, and result is obvious. This is not a limitation of the Blackfin architecture, but simply demonstrates that uClinux is designed to support devices without an MMU.

End of Part I

This is all I know well about uClinux on Blackfin. I have to look deeper into uClinux and I shall try to include more next time!

References

For more information, please visit http://blackfin.uclinux.org.

Talkback: Discuss this article with The Answer Gang

[BIO]

I'm currently doing my final semester as a Btech in Computer Science and Engineering in MES College of Engineering, Kuttipuram, Kerala, India. I am really fond of everything about Linux operating systems, maybe because I want to know more about it, and I spend most of the time on my PC for the same. My other areas of interest include reading, web surfing, and listening to music.


Copyright © 2006, Jesslyn Abdul Salam. Released under the Open Publication license unless otherwise noted in the body of the article. Linux Gazette is not produced, sponsored, or endorsed by its prior host, SSC, Inc.

Published in Issue 123 of Linux Gazette, February 2006

A Short Tutorial on XMLHttpRequest()

By Bob Smith

Introduction

This tutorial will show you how to build a web page that responds to asynchronous events. In five simple exercises, we'll show you the core of an Asychronous JavaScript And XML (AJAX) application. You'll have to learn a little JavaScript, but there's no requirement to learn anything about XML. Our goal is to show you how to build a responsive web application with a minimum investment of time.

What you should already know: You should be familiar with basic web page creation and have a general idea of the client/server nature of web page requests. You should also understand how CGI programs work and have some experience with CGI programming; we use a few lines of PHP in our exercises, but you can replace this with C or Perl if you wish.

Requirements for the examples: To do the exercises in this tutorial, you will need a browser with JavaScript enabled. JavaScript is on by default in most browsers, so this shouldn't require any action on your part unless you prevously disabled it. You will also need to have a web server that supports PHP and CGI, and the ability to upload web pages to it. You should be ready to go if you already have Apache and PHP installed on your PC; in fact, our exercises assume that you're using your PC for the web server.

Application Overview

To illustrate the need for AJAX, let's consider a real-world example: we've built a telephone answering machine and we want the caller ID information to be presented on a web page, which we can view while we are at home or at work. The data flow in our application looks something like this: 

  (answering_machine -> syslog -> fifo -> Apache -> web_page)
Our answering machine will log caller ID information via syslog using LOG_LOCAL3, a facility not used by any other applications on our system, and a syslog rule in '/etc/syslog.conf' will direct messages with this facility to a FIFO located in the Apache document directory. In this tutorial, we will deal with getting the strings from that FIFO to display on a web page. Writing to a FIFO is the asynchronous part of our sample application.

Getting Started

In the first exercise, we are going to test the development environment by running a simple PHP application. Save the following program as getfifo.php in the document directory of your web server: 

<?php
  $fp = fopen("ajaxfifo", "r");
  if ($fp) {
    $ajaxstring = fgets($fp, 128);
    fclose($fp);
  }

  header("Content-Type: text/html");
  print($ajaxstring);
?>
Now, create a fifo in the same directory: 
mkfifo ajaxfifo
Try to view getfifo.php using your web browser; it should hang, waiting for the read of 'ajaxfifo' to complete. Write some data to the FIFO before the browser times out: 
echo "Hello, World" > ajaxfifo
The text that you entered should appear in your browser window. Continue on to the next exercise if the data was displayed properly. If the data did not appear, go back and verify that the web server and PHP are installed and working properly.

DOM in Two Lines of Code

JavaScript is an object-oriented language and treats a displayed web page as an object. The Document Object Model, or DOM, describes the objects, properties, and verbs (or methods) available within JavaScript. By using the DOM, you can name different parts of a web page and can then perform different actions on those parts.

The following exercise verifies that JavaScript is enabled in your browser by creating a named region on a web page, and putting some text into that named region. Copy the following program to hello.html in the document directory of your web server: 

<html>
<head>
<title>Exercise 2: Use DOM to Test JavaScript</title>

<script language=javascript type="text/javascript">
<!-- Hide script from non-JavaScript browsers

  // SayHello() prints a message in the document's "hello" area
  function SayHello() {
    document.getElementById("hello_area").innerHTML="Hello, World";
    return;
  }

-->
</script>
</head>

<body onload="SayHello()">
<h3><center>Exercise 2:  Use DOM to Test JavaScript</center></h3>
</p>
<div id="hello_area">This text is replaced.</div>
</body>
</html>
The above code defines a section of the web page as "hello_area" and uses the subroutine SayHello() to put text in that section. Load hello.html and verify that your browser's JavaScript displays "Hello, World" on the web page.

Callbacks in JavaScript

A callback is a subroutine that is called when a particular event occurs. JavaScript has a fairly complete set of events to which you can attach a callback. The following program starts a timer using a callback that is invoked when the page is loaded, and a callback associated with the timer displays a counter and restarts itself. Copy this program to callback.html in your server's document directory, and verify that the count is updated in your browser window every two seconds. 
<html>
<head>
<title>Exercise 3: A JavaScript Callback Demo</title>

<script language=javascript type="text/javascript">
<!-- Hide script from non-JavaScript browsers
  var count;
  count = 0;

  // Put the current count on the page
  function DisplayCount() {
    // Put current time in the "count" area of the web page
    document.getElementById("count_area").innerHTML=
      "The count is: " + count++;

    // Schedule next call to DisplayCount
    setTimeout("DisplayCount()", 2000);
    return;
  }
-->
</script>
</head>

<body onload="DisplayCount()">
<h3><center>Exercise 3: A JavaScript Callback Demo</center></h3>
<div id="count_area">This text is replaced.</div>
</body>
</html>

How to use XMLHttpRequest()

XMLHttpRequest is a JavaScript subroutine that lets you make an HTTP request and attach a callback to the response. Since the response has a callback, the browser is free to continue responding to user input. In a way, XMLHttpRequest is to JavaScript what select() is to C - a way to wait for an event. XMLHttpRequest() is what puts the 'A' in AJAX.

The following exercise adds only XMLHttpRequest() to the previous examples. We request the data from getfifo.php using XMLHttpRequest(), and tie a callback to the arrival of the response. The response callback displays the data using a named division per the DOM. Copy the following code into async.html: 

<html>
<head>
<title>Exercise 4: An XMLHttpRequest() Demo</title>

<script language=javascript type="text/javascript">
<!-- Hide script from non-JavaScript browsers

  var req_fifo;

  // GetAsyncData sends a request to read the fifo.
  function GetAsyncData() {
    url = "getfifo.php";

    // branch for native XMLHttpRequest object
    if (window.XMLHttpRequest) {
      req_fifo = new XMLHttpRequest();
      req_fifo.abort();
      req_fifo.onreadystatechange = GotAsyncData;
      req_fifo.open("POST", url, true);
      req_fifo.send(null);
    // branch for IE/Windows ActiveX version
    } else if (window.ActiveXObject) {
      req_fifo = new ActiveXObject("Microsoft.XMLHTTP");
      if (req_fifo) {
        req_fifo.abort();
        req_fifo.onreadystatechange = GotAsyncData;
        req_fifo.open("POST", url, true);
        req_fifo.send();
      }
    }
  }

  // GotAsyncData is the read callback for the above XMLHttpRequest() call.
  // This routine is not executed until data arrives from the request.
  // We update the "fifo_data" area on the page when data does arrive.
  function GotAsyncData() {
    // only if req_fifo shows "loaded"
    if (req_fifo.readyState != 4 || req_fifo.status != 200) {
      return;
    }
    document.getElementById("fifo_data").innerHTML=
      req_fifo.responseText;

    // Schedule next call to wait for fifo data
    setTimeout("GetAsyncData()", 100);
    return;
  }

-->
</script>

</head>
<body onload="GetAsyncData()">
<h3>Exercise 4: An XMLHttpRequest() Demo</h3><p>
<div id="fifo_data"> </div>

</body>
</html>
Load async.html and, if all has gone well, everything sent to ajaxfifo will appear in the browser window. For example: 
echo "Hello, AJAX" > ajaxfifo
Sample screen for Exercise 4

An Appliance Web UI

If you were building an appliance (such as our answering machine), you'd want your web UI to respond to events occuring in the appliance; the exercises above show how to do this. But you might also want your appliance UI to have some controls available to the user. The final exercise below adds code to the previous exercise to show you how to tie buttons in a web form to JavaScript subroutines. This exercise demonstrates that a web UI can wait for asynchronous events and still be interactive.

Copy async.html to a file called webui.html and add the following subroutine to the JavaScript code: 

// setColor updates the "color_area" with the color specified
  function setColor(new_color) {
    color_text = "<table border=2 bgcolor=";
    if ("Blue" == new_color) {
      color_text += "\"Blue\">"
    }
    else if ("Red" == new_color) {
      color_text += "\"Red\">"
    }
    else {       // shouldn't get here
      color_text += "\"Green\">"
    }
    color_text += "<tr><td>A little color</td></tr></table>";
    document.getElementById("color_area").innerHTML=color_text;
  }
Add a form to the HTML part of webui.html: 
<body onload="GetAsyncData()">
<h3>Exercise 5: A Trivial Web UI</h3><p>
<div id="fifo_data"> </div>
<p>
<div id="color_area">No color yet.</div><p>
<form>
<input type=button value="Blue" onClick="setColor('Blue')">
<input type=button value="Red" onClick="setColor('Red')">
</form>
</body>

Summary and Notes

In this short tutorial, we've explored the fundamentals for building responsive, interactive web interfaces using JavaScript and XMLHttpRequest(). In order to focus on the core concepts, we've ignored many important details, such as error handling and return codes. Hopefully, you can add the techniques shown in this article to your web toolbox.

FIFO versus /dev/fanout: Open two browser windows displaying async.html and write some data into the FIFO; notice that the data that you write will appear in only one window. This is because the FIFO passes the data to only one of the readers. In a real application, we would want to use a fanout device so that the data is written to all readers. Fanout is described in a previous Linux Gazette article as well as on the author's home page.

XML: If you are getting only a single piece of data from your web server, you can use the code in this article. As soon as you ask for more than one piece of data, you should switch to XML. It does not need to be difficult.

As an example, let's say that you've modified getfifo.php to use the caller ID to look up the time and duration of the last time you spoke with the caller, and you want to return this information along with the caller ID string. The PHP code to build an XML response for the three pieces of data might look like this: 

<?php
  header("Content-Type: text/xml");
  print("<?xml version=\"1.0\" ?>\n");
  print("<caller_info>\n");
  printf("<caller_id>%s</caller_id>\n",       "Mary");
  printf("<lastcalltime>%s</lastcalltime>\n", "10:24 am");
  printf("<lastcalldur>%s</lastcalldur>\n",   "12:05");
  print("</caller_info>\n");
?>
Instead of using req_fifo.responseText to get the whole body of the reply, you would use the following to extract each of the three fields you want: 
  callid = req_fifo.responseXML.getElementsByTagName("caller_id");
  calltm = req_fifo.responseXML.getElementsByTagName("lastcalltime");
  calldur = req_fifo.responseXML.getElementsByTagName("lastcalldur");
  callid[0].childNodes[0].nodeValue;

  document.getElementById("caller_data").innerHTML=
    callid[0].childNodes[0].nodeValue;
  document.getElementById("lastcalltime").innerHTML=
    calltm[0].childNodes[0].nodeValue;
  document.getElementById("lastcalldur").innerHTML=
    calldur[0].childNodes[0].nodeValue;
There are simpler and better ways to do this, but the above code should give you an idea of what to expect.

Further reading: The Apple developer's web site has a good article on XMLHttpRequest(). You can find it here:
http://developer.apple.com/internet/webcontent/xmlhttpreq.html

You may find the tutorials at the JavaScript Kit web site to be a big help if you'd like to expand on the knowledge you've gained from this article. You can find their tutorials here:
http://www.javascriptkit.com/javatutors/

The IBM DeveloperWorks web site has some great articles on AJAX and XML. We found this one particularly useful:
http://www.ibm.com/developerworks/web/library/wa-ajaxintro1.html

Finally, you might be interested in the low cost answering machine that's at the heart of this author's appliance:
http://www.linuxtoys.org/answer/answering_machine.html

Talkback: Discuss this article with The Answer Gang

[BIO]

Bob is an electronics hobbyist and Linux programmer. He is one of the authors of "Linux Appliance Design" to be published by No Starch Press.


Copyright © 2006, Bob Smith. Released under the Open Publication license unless otherwise noted in the body of the article. Linux Gazette is not produced, sponsored, or endorsed by its prior host, SSC, Inc.

Published in Issue 123 of Linux Gazette, February 2006

Configuring Apache for Maximum Performance

By Vishnu Ram V

1 Introduction

Apache is an open-source HTTP server implementation. It is the most popular web server on the Internet; the December 2005 Web Server Survey conducted by Netcraft [1] shows that about 70% of the web sites on Internet are using Apache.

Apache server performance can be improved by adding additional hardware resources such as RAM, faster CPU, etc. But most of the time, the same result can be achieved by custom configuration of the server. This article looks into getting maximum performance out of Apache with the existing hardware resources, specifically on Linux systems. Of course, it is assumed that there is enough hardware resources - especially enough RAM that the server isn't swapping frequently. First two sections look into various Compile-Time and Run-Time configuration options. The Run-Time section assumes that Apache is compiled with prefork MPM. HTTP compression and caching is discussed next. Finally, using separate servers for serving static and dynamic contents is covered. Basic knowledge of compiling and configuring Apache and Linux are assumed.

2 Compile-Time Configuration Options

2.1 Load only the required modules:

The Apache HTTP Server is a modular program where the administrator can choose the functions to be included in the server by selecting a set of modules [2]. The modules can be compiled either statically as part of the 'httpd' binary, or as Dynamic Shared Objects (DSOs). DSO modules can either be compiled when the server is built, or added later via the apxs utility, which allows compilation at a later date. The mod_so module must be statically compiled into the Apache core to enable DSO support.

Run Apache with only the required modules. This reduces the memory footprint, which improves the server performance. Statically compiling modules will save RAM that's used for supporting dynamically loaded modules, but you would have to recompile Apache to add or remove a module. This is where the DSO mechanism comes handy. Once the mod_so module is statically compiled, any other module can be added or dropped using the 'LoadModule' command in the 'httpd.conf' file. Of course, you will have to compile the modules using 'apxs' if they weren't compiled when the server was built.

2.2 Choose appropriate MPM:

The Apache server ships with a selection of Multi-Processing Modules (MPMs) which are responsible for binding to network ports on the machine, accepting requests, and dispatching children to handle the requests [3]. Only one MPM can be loaded into the server at any time.

Choosing an MPM depends on various factors, such as whether the OS supports threads, how much memory is available, scalability versus stability, whether non-thread-safe third-party modules are used, etc.

Linux systems can choose to use a threaded MPM like worker or a non-threaded MPM like prefork:

The worker MPM uses multiple child processes. It's multi-threaded within each child, and each thread handles a single connection. Worker is fast and highly scalable and the memory footprint is comparatively low. It's well suited for multiple processors. On the other hand, worker is less tolerant of faulty modules, and a faulty thread can affect all the threads in a child process.

The prefork MPM uses multiple child processes, each child handles one connection at a time. Prefork is well suited for single or double CPU systems, speed is comparable to that of worker, and it's highly tolerant of faulty modules and crashing children - but the memory usage is high, and more traffic leads to greater memory usage.

3 Run-Time Configuration Options

3.1 DNS lookup:

The HostnameLookups directive enables DNS lookup so that hostnames can be logged instead of the IP address. This adds latency to every request since the DNS lookup has to be completed before the request is finished. HostnameLookups is Off by default in Apache 1.3 and above. Leave it Off and use post-processing program such as logresolve to resolve IP addresses in Apache's access logfiles. Logresolve ships with Apache.

When using 'Allow from' or 'Deny from' directives, use an IP address instead of a domain name or a hostname. Otherwise, a double DNS lookup is performed to make sure that the domain name or the hostname is not being spoofed.

3.2 AllowOverride:

If AllowOverride is not set to 'None', then Apache will attempt to open the .htaccess file (as specified by AccessFileName directive) in each directory that it visits. For example: 

DocumentRoot /var/www/html
<Directory />
AllowOverride all
</Directory>

If a request is made for URI /index.html, then Apache will attempt to open /.htaccess, /var/.htaccess, /var/www/.htaccess, and /var/www/html/.htaccess. These additional file system lookups add to the latency. If .htaccess is required for a particular directory, then enable it for that directory alone.

3.3 FollowSymLinks and SymLinksIfOwnerMatch:

If FollowSymLinks option is set, then the server will follow symbolic links in this directory. If SymLinksIfOwnerMatch is set, then the server will follow symbolic links only if the target file or directory is owned by the same user as the link.

If SymLinksIfOwnerMatch is set, then Apache will have to issue additional system calls to verify whether the ownership of the link and the target file match. Additional system calls are also needed when FollowSymLinks is NOT set.
For example: 

DocumentRoot /var/www/html
<Directory />
Options SymLinksIfOwnerMatch
</Directory>
For a request made for URI /index.html, Apache will perform lstat() on /var, /var/www, /var/www/html, and /var/www/html/index.html. These additional system calls will add to the latency. The lstat results are not cached, so they will occur on every request.

For maximum performance, set FollowSymLinks everywhere and never set SymLinksIfOwnerMatch. Or else, if SymLinksIfOwnerMatch is required for a directory, then set it for that directory alone.

3.4 Content Negotiation:

Avoid content negotiation for fast response. If content negotiation is required for the site, use type-map files rather than Options MultiViews directive. With MultiViews, Apache has to scan the directory for files, which adds to the latency.

3.5 MaxClients:

The MaxClients sets the limit on maximum simultaneous requests that can be supported by the server; no more than this number of child processes are spawned. It shouldn't be set too low; otherwise, an ever-increasing number of connections are deferred to the queue and eventually time-out while the server resources are left unused. Setting this too high, on the other hand, will cause the server to start swapping which will cause the response time to degrade drastically. The appropriate value for MaxClients can be calculated as:

[4] MaxClients = Total RAM dedicated to the web server / Max child process size

The child process size for serving static file is about 2-3M. For dynamic content such as PHP, it may be around 15M. The RSS column
in "ps -ylC httpd --sort:rss" shows non-swapped physical memory usage by Apache processes in kiloBytes.

If there are more concurrent users than MaxClients, the requests will be queued up to a number based on ListenBacklog directive. Increase ServerLimit to set MaxClients above 256.

3.6 MinSpareServers, MaxSpareServers, and StartServers:

MaxSpareServers and MinSpareServers determine how many child processes to keep active while waiting for requests. If the MinSpareServers is too low and a bunch of requests come in, Apache will have to spawn additional child processes to serve the requests. Creating child processes is relatively expensive. If the server is busy creating child processes, it won't be able to serve the client requests immediately. MaxSpareServers shouldn't be set too high: too many child processes will consume resources unnecessarily.

Tune MinSpareServers and MaxSpareServers so that Apache need not spawn more than 4 child processes per second (Apache can spawn a maximum of 32 child processes per second). When more than 4 children are spawned per second, a message will be logged in the ErrorLog.

The StartServers directive sets the number of child server processes created on startup. Apache will continue creating child processes until the MinSpareServers setting is reached. This doesn't have much effect on performance if the server isn't restarted frequently. If there are lot of requests and Apache is restarted frequently, set this to a relatively high value.

3.7 MaxRequestsPerChild:

The MaxRequestsPerChild directive sets the limit on the number of requests that an individual child server process will handle. After MaxRequestsPerChild requests, the child process will die. It's set to 0 by default, the child process will never expire. It is appropriate to set this to a value of few thousands. This can help prevent memory leakage, since the process dies after serving a certain number of requests. Don't set this too low, since creating new processes does have overhead.

3.8 KeepAlive and KeepAliveTimeout:

The KeepAlive directive allows multiple requests to be sent over the same TCP connection. This is particularly useful while serving HTML pages with lot of images. If KeepAlive is set to Off, then for each images, a separate TCP connection has to be made. Overhead due to establishing TCP connection can be eliminated by turning On KeepAlive.

KeepAliveTimeout determines how long to wait for the next request. Set this to a low value, perhaps between two to five seconds. If it is set too high, child processed are tied up waiting for the client when they could be used for serving new clients.

4 HTTP Compression & Caching

HTTP compression is completely specified in HTTP/1.1. The server uses either the gzip or the deflate encoding method to the response payload before it is sent to the client. Client then decompresses the payload. There is no need to install any additional software on the client side since all major browsers support these methods. Using compression will save bandwidth and improve response time; studies have found a mean gain of %75.2 when using compression [5].

HTTP Compression can be enabled in Apache using the mod_deflate module. Payload is compressed only if the browser requests compression, otherwise uncompressed content is served. A compression-aware browser inform the server that it prefer compressed content through the HTTP request header - "Accept-Encoding: gzip,deflate". Then the server responds with compressed payload and the response header set to "Content-Encoding: gzip".

The following example uses telnet to view request and response headers: 

bash-3.00$ telnet www.webperformance.org 80
Trying 24.60.234.27...
Connected to www.webperformance.org (24.60.234.27).
Escape character is '^]'.
HEAD / HTTP/1.1
Host: www.webperformance.org
Accept-Encoding: gzip,deflate

HTTP/1.1 200 OK
Date: Sat, 31 Dec 2005 02:29:22 GMT
Server: Apache/2.0
X-Powered-By: PHP/5.1.1
Cache-Control: max-age=0
Expires: Sat, 31 Dec 2005 02:29:22 GMT
Vary: Accept-Encoding
Content-Encoding: gzip
Content-Length: 20
Content-Type: text/html; charset=ISO-8859-1
In caching, a copy of the data is stored at the client or in a proxy server so that it need not be retrieved frequently from the server. This will save bandwidth, decrease load on the server, and reduce latency. Cache control is done through HTTP headers. In Apache, this can be accomplished through mod_expires and mod_headers modules. There is also server side caching, in which the most frequently-accessed content is stored in memory so that it can be served fast. The module mod_cache can be used for server side caching; it is production stable in Apache version 2.2.

5 Separate server for static and dynamic content

Apache processes serving dynamic content take from 3MB to 20MB of RAM. The size grows to accommodate the content being served and never decreases until the process dies. As an example, let's say an Apache process grows to 20MB while serving some dynamic content. After completing the request, it is free to serve any other request. If a request for an image comes in, then this 20MB process is serving static content - which could be served just as well by a 1MB process. As a result, memory is used inefficiently.

Use a tiny Apache (with minimum modules statically compiled) as the front-end server to serve static contents. Requests for dynamic content should be forwarded to the heavy-duty Apache (compiled with all required modules). Using a light front-end server has the advantage that the static contents are served fast without much memory usage and only the dynamic contents are passed over to the big server.

Request forwarding can be achieved by using mod_proxy and mod_rewrite modules. Suppose there is a lightweight Apache server listening to port 80 and a heavyweight Apache listening on port 8088. Then the following configuration in the lightweight Apache can be used to forward all requests (except requests for images) to the heavyweight server:
[9]

ProxyPassReverse / http://%{HTTP_HOST}:8088/
RewriteEngine on                                            
RewriteCond  %{REQUEST_URI} !.*\.(gif|png|jpg)$
RewriteRule ^/(.*) http://%{HTTP_HOST}:8088/$1 [P]
All requests, except for images, will be proxied to the backend server. The response is received by the frontend server and supplied to the client. As far as client is concerned, all the responses seem to come from a single server.

6 Conclusion

Configuring Apache for maximum performance is tricky; there are no hard and fast rules. Much depends on understanding the web server requirements and experimenting with various available options. Use tools like ab and httperf to measure the web server performance. Lightweight servers such as tux or thttpd can also be used as the front-end server. If a database server is used, make sure it is optimized so that it won't create any bottlenecks. In case of MySQL, mtop can be used to monitor slow queries. Performance of PHP scripts can be improved by using a PHP caching product such as Turck MMCache. It eliminates overhead due to compiling by caching the PHP scripts in a compiled state.

Bibliography

1. http://news.netcraft.com/archives/web_server_survey.html
2. http://httpd.apache.org/docs/2.2/dso.html
3. http://httpd.apache.org/docs/2.2/mpm.html
4. http://modperlbook.org/html/ch11_01.html
5. http://www.speedupyoursite.com/18/18-2t.html
6. http://www.xs4all.nl/~thomas/apachecon/PerformanceTuning.html
7. http://www.onlamp.com/pub/a/onlamp/2004/02/05/lamp_tuning.html
8. http://httpd.apache.org/docs/2.2/misc/perf-tuning.html
9. Linux Server Hacks by Rob Flickenger

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[BIO]

I'm an MTech. in Communication Systems from the IIT Madras. I joined Poornam Info Vision Pvt Ltd. in 2003 and have been working for Poornam since then.

My area of interest are performance tuning, server monitoring, and security. In my free time I practice Karate, read books and listen to music.


Copyright © 2006, Vishnu Ram V. Released under the Open Publication license unless otherwise noted in the body of the article. Linux Gazette is not produced, sponsored, or endorsed by its prior host, SSC, Inc.

Published in Issue 123 of Linux Gazette, February 2006

HelpDex

By Shane Collinge

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Click here to see the full-sized image

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All HelpDex cartoons are at Shane's web site, www.shanecollinge.com.

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[BIO] Part computer programmer, part cartoonist, part Mars Bar. At night, he runs around in his brightly-coloured underwear fighting criminals. During the day... well, he just runs around in his brightly-coloured underwear. He eats when he's hungry and sleeps when he's sleepy.

Copyright © 2006, Shane Collinge. Released under the Open Publication license unless otherwise noted in the body of the article. Linux Gazette is not produced, sponsored, or endorsed by its prior host, SSC, Inc.

Published in Issue 123 of Linux Gazette, February 2006

The Linux Launderette

Contents:

(?)Unauthori[sz]ed Practice of Law statutes
(?)Yet another "case study" (RadioShack Saves Millions of Dollars by Choosing Windows over Linux)
(?)RadioShack... and ferrets?
(?)Google
(?)Everything you ever wanted to know about C types, Part 1: What's in a type?
(?)Open Source cuddly penguins
(?)Ultra-cool gadgetry
(?)The usual brilliant Redmond strategy: checkmate in two moves
(?)3 Cyrillic spams

(?) Unauthori[sz]ed Practice of Law statutes

Sat, 31 Dec 2005

From Predrag Ivanovic

Answered By: Rick Moen

Rick, does this qualify?

He had to remove list of Linux compatible Bluetooth devices from the site, because "[undisclosed] registered member of the Bluetooth SIG complained about the non-qualified use of Bluetooth products on this page and the features document." Altough the BlueZ protocol stack is now qualified as a Bluetooth subsystem, the list is still not there.

(!) [Rick] Pedja, thank you for the suggestion.
I did follow that at the time that it was a current news item, The sum and substance seems to be that the (unnamed) Bluetooth Qualification Administrator asserted (repeating the allegations of a third party) that Holtzmann had been distributing information about not-yet-certified software or hardware products ("non-qualified products") that had been entrusted to him under nondisclosure (the "Bluetooth License Agreement") as a member of the private Bluetooth SIG. Or alternatively that Holzmann was violating his agreement by asserting that his BlueZ protocol stack was "Bluetooth" compatible, when it had not passed the required certification steps at that time. Or both. Or something similar.

(?) Well,according to this all he did is list drivers which are needed for some BT device to work with Linux. I couldn't find anywhere "Device $foo is certified by Bluetooth authority as working."

(!) [Rick] I don't want to make it seem as if I'm making excuses for the unnamed Bluetooth Qualification Administrator, but Holzmann may have agreed in his "Bluetooth License Agreement" to use the term "Bluetooth" only in relation to certified products. It's not entirely clear, what their objection was.
(!) [Rick] The problem is that the complaint may have been justified. We don't have enough information to decide one way or the other.
But it's very common to tie trademark-licensing rights to compliance with an industry-controlled certification suite. I can easily imagine Holzmann getting caught in one of those pitfalls -- and no actual malfeasance being visited upon him by the industry consortium.

(?) So, device is BT-compliant ONLY if it passed official certification, and since BlueZ was not certified at the time, listing products that work with it is considered a violation of some sort, right? And Holzmann received a slap on the wrist for doing that, so it seems. If that's the situation, based on info I have and your analysis, this is just another case of $institution enforcing strict regulations. I thought that only federal/government agencies (FAA,FCC etc.) are that strict.

(!) [Rick] Well, this is claimed to be based in some contractual agreement.
Contract violation isn't punishable in the way crimes are -- the former being merely civil disputes between parties. In retrospect, I really do think this entire case was about trademark rights, enforced with the aid of a rather aggressively worded contract. Which Holzmann signed. We have no way of knowing if he actually acted in violation of that contract (neither side having published the terms in question), but that's what's alleged.
An additional lesson is possible from noting that, stipulating that Holzmann was caught violating some contract he had agreed to, nonetheless the sky didn't fall. The parties just worked out the complaint, and moved on.
As I've observed many times, many computerists have a comical and self-destructive tendency to run shrieking in terror, seeking permission to capitulate, the moment they see a paper (or even e-mail!) demanding something, that looks as if it's been breathed on by a lawyer. I can imagine that the idea of an actual tort (such as violation of contract) would inspire them to fainting spells.
A "tort" in the USA and other British-derived legal systems is a civil wrong, i.e., a non-criminal action or failure to act, that had the effect of making the person involved (the "tort-feasor") fail an obligation towards someone else. The state has no part in civil litigation, except to supply the courts and judges: Each party pays his/her own legal expenses, and must convince a judge that a wrong has been committed through a "preponderance of the evidence". (Criminal cases, by contrast, must be proved by the state per the much higher standard of evidence being convincing "beyond any reasonable doubt".)
Generally speaking, all you can get if you win a civil suit is either correction of the wrongful situation (a "remedy in equity") or a money payment from the other side in compensation of your loss (a "remedy in law"). Sometimes , you can get an order that the other side pay your legal expenses. For a minority of torts in which the plaintiff is able to show particular recklessness, plaintiff can get "special" or "exemplary" damages to deter other people from being screw-ups in that way, in the future.
But that's really about it.
Now, people justly fear being sued (hauled into civil litigation) simply because of expense of legal representation, but that is a sword that cuts both ways (not to mention that "Discovery should prove interesting" threat I cited earlier). Therefore, most civil conflicts never go to court, even in the much-too-litigious USA, and even in cases where sundry threats of litigation have flown back and forth.
People go to court because either they're crazy, or because the other side refuses to compromise and plaintiff thinks he/she can win big enough to merit the time and expense. Fortunately for our sanity, that happens rarely.
(!) [Rick] One lesson is: Be careful what contracts you agree to. If the "Bluetooth License Agreement" stipulates that you may not use a certain trademark-encumbered term without passing the associated certification suite, then either decline the agreement or be prepared to live with its restrictions.

(?) Excelent advice. "Always read the fine print" and "Use your common sense".

(?) Yet another "case study" (RadioShack Saves Millions of Dollars by Choosing Windows over Linux)

Wed, 04 Jan 2006

From Predrag Ivanovic

If TAG isn't place for this,I'm sorry,but I just had to share few quotes from this...case study[1]. URL says it all, really...

(!) [Jason] Heh heh. Just skimming it, one thing is obvious: They're scared.

(?) "Benefits that the company expects to realize by choosing Windows include a lower total cost of ownership, simplified system management and deployment of software updates, reduced staffing and training requirements, improved system reliability and security, and... reduced exposure to the risk of intellectual property infringement claims."

[...]

"Highly skilled resources for the Windows platform cost significantly less than similarly skilled resources for Linux," says Cook. "Had we selected Linux, I'm sure that we would have incurred significant additional staffing costs."

(!) [Jason] Hey kids! Get your A+ Certification, so you can work for less than a *NIX admin! :)

(?) [..]

"Unlike many Linux vendors, Microsoft provides its customers with strong indemnification against patent, copyright, trade secret, and trademark infringement claims without a monetary limit--part of its commitment to ensuring that licensing issues and questions of intellectual property do not present problems for customers."

[1] http://www.microsoft.com/windowsserversystem/facts/casestudies/CaseStudy.aspx?CaseStudyID=17131

(!) [Ben] So they bought^Wfound themselves a supporter at Radio Shack who, in his own words, is "a strong advocate of Wind0ws XP Embedded" (note that he's the only one they quote throughout the entire "case study".) Everyone here is shocked - shocked, I tell you - what an unusual tactic for Micr0s0ft!
I stopped being outraged, or even bothered by this a long, long time ago. If you're going to read this kind of stuff, I suggest that you adopt the same attitude; let them make the noise, and we'll keep on producing the better OS. :) Those who are swayed by empty claims will do their thing; the people and companies who actually have to watch their bottom line instead of engaging in managerial dicksize wars will do theirs. And Linux will keep growing just as it has. Quietly, and regardless of Micr0s0ft "case studies".
(!) [Jason]
http://en.wikipedia.org/wiki/David_Zamos
(!) [Rick] Which links to a "Cleveland Scene" article that's the most entertaining read I've had in a long time.
Short version: Zamos was a 21-year-old impoverished student who couldn't use the XP educational copy he bought, tried to return it under Microsoft's return policy and was rather unscrupulously denied, tried to sell it on eBay, had his auction questionably cancelled by a Microsoft flack, recertified his auction as lawful and then sold the copy, was sued by Microsoft on ridiculous copyright and trademark charges, countersued on several charges while proving in court (represented only by himself) that the lawsuit was bogus and the company's actions repeatedly in bad faith, got international publicity for the lopsided court fight that he seemed poised to win, insisted on a jury trial, and eventually accepted a settlement that included a gag agreement.
All his countersuit had requested was an apology and reimbursement for his $60 product cost. Microsoft refused, and thus ended up being taken to the cleaners -- in front of the entire world -- by a 21-year-old pro-se litigant with a $3,500 annual gross income.

(?) RadioShack... and ferrets?

Wed, 04 Jan 2006

From Predrag Ivanovic

(?) "Unlike many Linux vendors, Microsoft provides its customers with strong indemnification against patent, copyright, trade secret, and trademark infringement claims without a monetary limit--part of its commitment to ensuring that licensing issues and questions of intellectual property do not present problems for customers."

(!) [Sluggo] Regarding the last one... Microsoft is allowing you to pay them off to avoid a problem they themselves caused?
Isn't that what Ben used to do for the KGB? I thought it was called "Extortion" though.
(!) [Ben] You keep missing it, Mike. What I used to do is take people who called it extortion - even those who _didn't_ capitalize the word - stuff'em in a sack with hungry ferrets on crack, and toss'em into a large dryer. Cost me $2.50 each time, but it was worth it.
(!) [Jimmy] Now... that's just kind. I would use crack-addicted hungry ferrets, but I'd make sure they were going through withdrawal... mainly just to see if they'd eat'em or smoke'em.
(!) [Ben] Jimmy, from here on, I'll leaving the design of these things to you. I'm obviously getting behind the times, getting old and weak and decrepit... I'll just do the knee-smashing, the spine-breaking, and the skull-cracking, and you can do the hard bits.
(!) [Ben] Say... how's your mustelid quotient these days? Need to be upped any? 'Cause, y'know, I have low friends in high places; we can oblige.
(!) [Jimmy] I'm just amused by the mental picture I have of a ferret holding a pipe. In a sack, obviously.
(!) [Ben] I'd imagine that you could bribe Heather and get a JPG. :)

(?) Google

Tue, 24 Jan 2006

From Mike Orr

http://slashdot.org/articles/06/01/24/1726241.shtml

'Google's product development pipeline runs at such a fast rate that it's very difficult for any company, Microsoft or Yahoo! to catch up.'

That couldn't be because they leverage and support open source, could it?

(!) [Rick] You know, these stories, are, like, too spazzed out unless you run them through the Valspeak filter:
http://www.80s.com/cgi-bin/valley.cgi?url=slashdot.org/articles/06/01/24/1726241.shtml

(?) That's great!

Yahoo! Like, oh my gawd! gives up quest for scope dominance

Yahoo! Like, oh my gawd! Inc., one of the first Network for, like, total
spazzes scope companies, totally has capitulated to Google Inc. in the
battle for market dominance.
"We totally don't think it's reasonable to assume we're going to gain a lot
of share from Google," Chief Financial Officer Susan Decker said in an
interview. "It's not our goal to be No. 1 in Network for, like, total
spazzes search. We would be very happy to maintain our market
share."

I hope Thomas isn't getting a heart attack.

(!) [Thomas] I'm like, "no way".

(?) Everything you ever wanted to know about C types, Part 1: What's in a type?

Thu, 05 Jan 2006

From Jimmy O'Regan

http://www-128.ibm.com/developerworks/power/library/pa-ctypes1/?ca=dgr-lnxw02CTypesP1

...............

"It is also possible to provide an incomplete definition of a structure or union type, providing the tag name but not the contents. Such an incomplete type cannot be directly used, but pointers to such a type can be used (but not dereferenced). You can use this to provide a level of encapsulation many people don't realize is possible in C.

Listing 3. Encapsulation in C.

       /* foo.h */
        struct foo_hidden;
        typedef struct foo_hidden *foo;
        extern foo new_foo();
        extern void delete_foo(foo);

        /* foo.c */
        struct foo_hidden {
                /* contents go here */
        };
... the <stdio.h> API never manipulates a FILE object directly, only pointers to FILE objects. In fact, such systems are entirely conforming. The humorous "Your stdio doesn't appear very std." message that Perl's Configure script emits when it can't figure out how to poke around inside a private structure is simply false."

...............

(?) Open Source cuddly penguins

Wed, 04 Jan 2006

From Jimmy O'Regan

"This project provides 'executables' that enable you to make your own soft-toy Linux® penguin. To put it straight: You can find sewing patterns and a community to sew your own soft toy or stuffed Linux® Tux penguin here."
http://www.free-penguin.org

(?) Ultra-cool gadgetry

Tue, 03 Jan 2006

From Benjamin A. Okopnik

In the "not (yet) Linux" category: this is the cool gadget of the year - tablet computing on paper. I see some very, very interesting possibilities in the future for this thing if it gets into the mainstream.
http://www.mobilityguru.com/2005/12/19/pentop_computing_is_more_than_a_kids
http://www.flypentop.com

(?) The usual brilliant Redmond strategy: checkmate in two moves

Mon, 23 Jan 2006

From Benjamin A. Okopnik

Yes, but for *whom?*

http://www.gmtoday.com/news/technology/computers/topstory20.asp

Seems that Vista is going to require machines with more resources than (my estimate) half the US population, and probably 95% of the people in the rest of the world, own.

(!) [Sluggo] It worked for Windows 95....
Just what I need, a 3-D word processor.
(!) [Thomas] DDD? No wait, that's a debugger. Ah, I see now. :)

(?)

To be sure, Microsoft has said lesser computers will still be capable of
running Vista, just with some of the special features that differentiate
it from older versions of Windows automatically turned off.

"Lesser" computers? I love it.

Dell has a section on its Web site, at www.dell.com/vista, which
highlights computers the company recommends for those planning to
upgrade to Vista. For models for the home and home office, the
recommended desktop is priced at $1,749. The laptop costs $2,699.

Better and better, every day. Y'all ready to rush right out and buy the top-buck gizmo of the day?

(*Don't* anybody breathe. If Micr0s0ft actually falls for this one, we're home free.)

(?) 3 Cyrillic spams

Wed, 25 Jan 2006

From Rick Moen

Several spams got through over the last few days, in fairly quick succession: I think I've now closed that hole. As a reminder, this mailing list is a bit difficult to keep spam out of, because of the open postings setting. (Posters aren't required to subscribe.)

(!) [Jimmy] Oh. I thought you were giving us holiday suggestions ("Winter in Egypt" :)

(?) Essentially, although my mail server's most effective antispam measure is the RFC-compliance tests carried out during each attempted delivery (because most malware and other spam doesn't even try to observe proper SMTP requirements), my MTA's knack, a bit later, of vetting each posting through SpamAssassin is pretty useful, too.

Anyhow, as it turns out, some particularly clever spams insert SMTP headers intended to disable SMTP-time SpamAssassin checking on the receiving host. Today, I've changed the SA settings slightly, to make its semaphores a bit more difficult for spammers to forge. (The two most recent spams got through because I'd left that reconfiguration unfinished, with the effect, ironically, of disabling SA checking entirely until I realised my error.)

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Published in Issue 123 of Linux Gazette, February 2006

The Backpage

By Ben Okopnik

The Sound of Wedding Bells.mp3

In the Japanese garden It's been quite a tumultuous and busy month at LG, with some of the challenges and the upheaval being personal as well as professional. For one thing, your not-so-humble Editor-in-Chief just got married - and was lucky enough to have many of his friends, including several LG staffers, present at the ceremony. What a blast! My darling bride and I flew to Los Angeles for our wedding (that being where most of our families and friends live) and spent three days composed of high-speed driving, inventing solutions on the spot, and plain old insanity (liberally mixed with laughter) to substitute for anything resembling planning or preparation - since, in the full-bore manner that seems to be the default dynamic between the two of us, we had no time to prepare beforehand, other than renting a hall for the event and arranging for an old friend of ours to perform the ceremony.

This is certain to cause heart attacks among those who believe in having The Perfect Wedding that takes several years to plan and an army of helpers to execute (and in which a single broken fingernail signals the end of the world), but we managed to figure out and assemble everything - what to wear, what food to buy (and where), our vows (written the night before and completed that morning!) and the ceremony - in about 80 hours total... it all worked out without unreasonable amounts of stress, and even included spending time with family and friends, as well as private time. Call it amazing; we call it normal for the way the two of us do things. :)

To bring things back on topic - at least somewhat - the one constant factor in making all of this happen was my old Acer laptop with a Verizon AirCard, running Debian Linux. As I drove around L.A., taking corners on two wheels, Kat mercilessly hammered the keys and ripped innocent packets out of the air; in fact, if I stare hard enough - yes, the Acer has survived and is even now being used to write this - I think I can see significant wear on the keys used to spell 'maps.google.com'. To be sure, we relied on our friends and family to help us (they all came through in magnificent style) - but all the research, all the driving directions, all the options for locations and style and food and even entertainment came from the Acer. It was an amazingly geeky experience in the process... and a warm, loving, unforgettable event as a result.

That's what I call technology at its finest.


In-house Happenings

In other news, the Linux Gazette is undergoing a little internal rescheduling and re-arranging - please pardon the dust! As a result, The Answer Gang column is absent from this issue (don't worry - it'll be back next month.) Our Editor Gal (Heather Stern) and her helpers (Thomas Adam and Jimmy O'Regan) need a break once in a while, too... the most important rule for the LG staff is "Burnout Is Not Allowed". Among this batch of friends, we often have to gently remind each other (although sometimes, the meaning of 'gently' involves a large cluebat - I, for one, have a thick skull) to sit back, have a beverage of choice, and Just Breathe. If we're a column or an article short as a result for a given month... well, that's the way it has to be. What it takes to keep LG running is a bunch of willing, committed, and reasonably sane people - and taking care of ourselves and each other is the first priority.

On the other hand, we have a couple of new volunteers: Howard Dyckoff, who will be reviving our lapsed NewsBytes column, and Jan-Benedict Glaw, who has agreed to review the C code submitted by our authors. I'm very happy to welcome them aboard, and look forward to much pleasant cooperation in the future.

Just as a reminder, while I'm on the topic - we're always looking for volunteers, particularly proofreaders, editors, and technical reviewers. If you have some time and energy to contribute, the readership of LG will appreciate it - and you'll be doing something that benefits thousands of people, which is no small reward. If you're interested, please contact me and let me know in what capacity you'd like to help - and don't forget that new ideas for improving LG are always welcome.

B. Okopnik

Talkback: Discuss this article with The Answer Gang

picture Ben is the Editor-in-Chief for Linux Gazette and a member of The Answer Gang.

Ben was born in Moscow, Russia in 1962. He became interested in electricity at the tender age of six, promptly demonstrated it by sticking a fork into a socket and starting a fire, and has been falling down technological mineshafts ever since. He has been working with computers since the Elder Days, when they had to be built by soldering parts onto printed circuit boards and programs had to fit into 4k of memory. He would gladly pay good money to any psychologist who can cure him of the recurrent nightmares.

His subsequent experiences include creating software in nearly a dozen languages, network and database maintenance during the approach of a hurricane, and writing articles for publications ranging from sailing magazines to technological journals. After a seven-year Atlantic/Caribbean cruise under sail and passages up and down the East coast of the US, he is currently anchored in St. Augustine, Florida. He works as a technical instructor for Sun Microsystems and a private Open Source consultant/Web developer. His current set of hobbies includes flying, yoga, martial arts, motorcycles, writing, and Roman history; his Palm Pilot is crammed full of alarms, many of which contain exclamation points.

He has been working with Linux since 1997, and credits it with his complete loss of interest in waging nuclear warfare on parts of the Pacific Northwest.

Copyright © 2006, Ben Okopnik. Released under the Open Publication license unless otherwise noted in the body of the article. Linux Gazette is not produced, sponsored, or endorsed by its prior host, SSC, Inc.

Published in Issue 123 of Linux Gazette, February 2006

Tux