...making Linux just a little more fun!



[ In reference to "GRUB, PATA and SATA" in LG#141 ]

Matthias Urlichs [smurf at smurf.noris.de]

Mon, 06 Aug 2007 23:04:32 +0200

The reason UUIDs do not help has nothing to do with Linus' article: this is not a kernel vs. userland issue.

This is a kernel vs. BIOS device numbering issue. UUIDs don't help here because GRUB doesn't interpret them. In fact it cannot even read them because they're in the menu.lst file which grub cannot find in the first place. Catch-22, anyone?

In fact you need to go grub's command line on the bare metal (i.e. after installing it on a floppy), not from Linux. Otherwise there's no point. Your article should mention that.

Matthias Urlichs <smurf@smurf.noris.de>
{M:U} IT Design


[ In reference to "Serving Your Home Network on a Silver Platter with Ubuntu" in LG#141 ]

Raj Shekhar [rajlist at rajshekhar.net]

Mon, 06 Aug 2007 10:41:39 +0530

Some comments -

Section 8 - Configure your LAN machines

Use dhcp instead of trying to configure each machine individually.

Section 11 BIND DNS Server

another option is to use pdnsd as a caching nameserver.

Section 13 Samba file sharing

If you are only using linux boxes, you can also share using nfs. Caveats: it takes long time to mount large directories.

Section 14 TorrentFlux

Nice tip!


raj shekhar
facts: http://rajshekhar.net | opinions: http://rajshekhar.net/blog
I dare do all that may become a man; Who dares do more is none.

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[ In reference to "Who is using your Network?" in LG#141 ]

Ramanathan Muthaiah [rus.cahimb at gmail.com]

Tue, 7 Aug 2007 06:37:56 +0530


How would this be possible in computers running on leased IP addresses via DHCP ?

Section 3 Secure Shell

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

The simplest way to do this is to go to each computer and copy these files to a USB stick:

   cp /etc/ssh/ssh_host_rsa_key.pub /media/usb/<ip_addr>.rsa.pub
   cp /etc/ssh/ssh_host_dsa_key.pub /media/usb/<ip_addr>.dsa.pub
. . . . . .


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[ In reference to "Build a Six-headed, Six-user Linux System" in LG#124 ]

Ben Okopnik [ben at linuxgazette.net]

Wed, 15 Aug 2007 00:29:07 -0400

----- Forwarded message from Peter Sanders <plsander@us.ibm.com> -----

Subject: Re: [TAG] tkb: Talkback:124/smith.html
To: Ben Okopnik <ben@linuxgazette.net>
From: Peter Sanders <plsander@us.ibm.com>
Date: Fri, 10 Aug 2007 09:49:14 -0500
I just need to figure out which is easier:

- modifying a Live CD/DVD installation -- probably not the easiest to change on the fly or - get a big enough flash drive to hold a reasonalbly functional installation

Peter Sanders
t/l 553-6186  (507)253-6186

[ Thread continues here (7 messages/7.94kB) ]


[ In reference to "An NSLU2 (Slug) Reminder Server" in LG#141 ]

T Ziomek [t_ziomek at yahoo.com]

Thu, 2 Aug 2007 09:29:54 -0700 (PDT)

To pick a nit..."Mozilla Firefox use up, 3.7% in 4 months in Europe" is incorrect. FF use was up 3.7 [percentage] points, not 3.7 percent. The text under the headline gets this right when referring to a ~7 point gain in the past year.

Regards, Tom Ziomek

[ Thread continues here (2 messages/1.27kB) ]


[ In reference to "Preventing Domain Expiration" in LG#142 ]

s. keeling [keeling at nucleus.com]

Sun, 2 Sep 2007 17:17:42 -0600

Entertaining and informative article, Rick, as always. I hope I can consider some of my recent floundering with whois and linuxmafia.{com,net} as partial inspiration.

However, getting down to the picture at the .sig block, shouldn't you be doing more long distance bicycling? I always pictured you as one of those ca. 150 lb., wiry joggers gorging yourself on tofu. Instead, the picture shows you're either a sumo wrestler, a linebacker (a geek linebacker?!?), or you need to avoid burger joints more often. Oh, and that perl book behind you is pink. Doesn't that need an upgrade?

My perl books are pink too, and they suit me just fine (damnit). Sorry for the crack about the picture. I'd just prefer that folks like you outlive me (I'm a selfish that way).

P.S. Ben, looks like we need to fiddle with pinehelper.pl again. It's ignoring the bit in parens in the subject line, making "Subject: Talkback". Crap.

My version of your pinehelper.pl attached. This is pinehelper.pl called by FF (Debian stable/Etch Iceweasel), fwiw.

I've also just installed flashplayer-mozilla, which appears to handle swf better than swf-player, so maybe I can actually read the cartoons this time. :-)


Any technology distinguishable from magic is insufficiently advanced.
- -

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[ In reference to "Booting Knoppix from a USB Pendrive via Floppy" in LG#116 ]

Ben Okopnik [ben at linuxgazette.net]

Sun, 9 Sep 2007 17:46:48 -0400

[ cc'd to TAG ]

On Sun, Sep 09, 2007 at 05:00:03PM +0100, Andrew JRV Hunt wrote:

> I'm emailing about the following article:
> http://linuxgazette.net/116/okopnik1.html
> I'd like to know, for what version of knoppix is this (i tried with
> 5.1, it didn't work), and then also where you could get an old version
> (I've searched for Knoppix 3.8 which was the latest version of knoppix
> at the time but I can't find a download anywhere).

Well, that's exactly the problem. Shortly after I wrote that article, the Knoppix folks stopped using the "boot.img" method and switched to using "isolinux". If you can get hold of 3.3 - the version that I used - it should work fine. Otherwise, well, the kernel is just too big - period.

> If this fails, would it be possible that the script could be rewritten
> for knoppix 5.1 or that I could be sent the image to be written onto
> floppy?

It's not a question of the script; the problem is that the kernel itself - even before you add any modules, libs, etc. - is just too big to fit into a boot.img image (1.44MB). That pretty well shuts off the possibility.

You could approach it the other way, though: try downloading Puppy Linux, or Damn Small Linux. Either of those should fit on a flash drive just fine - and Puppy Linux definitely had a "boot from a flash drive" description on their site the last time I looked.

> PS. I tried emailing the tag email address which didn't work.

I assume you got it from some old resource. Try tag@lists.linuxgazette.net - we've been using that one since May 2005 or so.

* Ben Okopnik * Editor-in-Chief, Linux Gazette * http://LinuxGazette.NET *


[ In reference to "An NSLU2 (Slug) Reminder Server" in LG#141 ]

Silas S. Brown [ssb22 at cam.ac.uk]

Thu, 2 Aug 2007 17:24:28 +0100

Hi, I wonder if you'd like to put this in Talkback or 2-Cent Tips in the next issue:

Since writing the article, I found a couple of minor problems.

One was that the sound sometimes fails in such a way that is not detectable by the NSLU2 (for example the speaker is not connected properly), and to mitigate the possible consequences of this, I set my NSLU2 to start playing a recognisible tune using its internal speaker if an important alarm is not acknowledged. I wrote a script that can convert any MIDI file into commands for Johnathan Nightingale's "beep" utility (which is available in the "beep" package on the NSLU2 Debian distribution), and my "MIDI to beep" script is available at


The other is that the NSLU2 may sometimes hang if the USB connection to its primary disk is somehow jolted; use of its built-in hardware watchtog helps, but it's best if the watchdog is used in such a way that a disk hang will be noticed by the watchdog (which might not happen if the process that's writing to /dev/watchdog is constantly in RAM), so rather than running a watchdog program I decided to do it in root's crontab:

* * * * * echo >/dev/watchdog;sleep 20;echo >/dev/watchdog;sleep 20;echo >/dev/watchdog
i.e. write to /dev/watchdog 3 times a minute (the system will reboot if it's not written to for a whole minute). Doing it this way rather than in a self-conained process should result in a watchdog failure if the primary disk gets pulled out (resulting in it being unmounted) because bin/sleep will become unavailable. This is so even though it will normally be cached in RAM and incur little or no disk activity. The cron job is quite lightweight, since the code for "bash" can be shared with any other bash scripts that are running at the same time and therefore should not take up much of its own memory.

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[ In reference to "A Quick Introduction to R" in LG#138 ]

Urmi Trivedi [urmi208 at gmail.com]

Tue, 31 Jul 2007 09:20:51 +0100

Dear Answer-gang,

I have gone through this article regarding plotting the data-labels in R. I found quite helpful functions but didn't find what i required. I have already plotted two matrices against one another and wish to label them I want to label the data-points plotted on the scatter-plots. Can you tell me if there is any way to do that?

Thanking you,

Yours truly,

Urmi Trivedi.

[ Thread continues here (2 messages/1.99kB) ]


[ In reference to "/okopnik.html" in LG#issue52 ]

Ben Okopnik [ben at linuxgazette.net]

Thu, 2 Aug 2007 11:34:49 -0400

Hi, Garrett -

[ cc'd to The Answer Gang ]

On Tue, Jul 31, 2007 at 08:37:39PM -0700, garrett.ellis@cox.net wrote:

> (Also sent to ben-fuzzybear@yahoo, but I wasn't sure that address remained valid.)
> Mr. Okopnik,
> An article of yours from the April 2000 Linux Gazette may have just
> saved me from hours of beating my head against my desk. Granted, I'd
> already spent about 12 hours beating my head against my desk, so
> further damage (if possible) has been averted.

Heh. I've left the imprint of my forehead on at least a few brick walls, so - yes, that sounds like a positive effect.

> See, I was doing some basic security changes on several hundred
> systems. My Expect powers are not yet strong enough to automate this
> task, but that's an aside. I've spent the last several days running
> find commands with various -exec, and as it turns out, I managed to
> annhiliate a RHEL4 Selinux system with the following:
> find / -user root -perm -o+w -exec chmod 0600 '{}' \;
> # I forgot "-type f" eek!

('-type f' wouldn't have helped much, I'm afraid. It would have stopped you from messing up, say, the entries in '/dev' - but that's about it.)

Ouch! You've "discovered" (and I use that in the most sympathetic way possible) the power of the 'find' command. It's very similar to a Milwaukee "Hole Hawg" drill: it will drill any hole you want it to - whether it's through concrete, steel, or your leg...

(See this love paean to a Super Hawg: http://www99.epinions.com/content_246549155460)

Unix tools are kinda like that. Huge amounts of power - and the safety is assumed to come from experience and forethought. Experience, however, is what you get when you didn't have enough experience and forethought!

> For hours afterwards, nothing would execute even when I restored
> execute permissions (on binaries only) from a Rescue CD. Your article
> pointed out the need for +x on some (if not all) shared libs, and that
> allowed me to rescue the machine.
> Thank you. Thank you. I owe you one, two, or ten beers.

[smile] Thanks, Garrett. I probably shouldn't say this - it's likely to lose me a beer or two - but if I was in your place, I'd actually reinstall the system from scratch; at the very least, I'd run a comparison of everything in '{,/usr}{/bin,/sbin,/lib}/' against a "normal" system. Given that you now have an uncertain set of permissions, all sorts of security vulnerabilities and possible future problems seem likely. The fact that your system works now gives you some breathing room time-wise - but I wouldn't call it a closed case.

* Ben Okopnik * Editor-in-Chief, Linux Gazette * http://LinuxGazette.NET *

[ Thread continues here (2 messages/5.43kB) ]

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Published in Issue 143 of Linux Gazette, October 2007