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More 2 Cent Tips!

See also: The Answer Gang's Knowledge Base and the LG Search Engine

[LG 105] 2c Tips #5: Open X-change

Jimmy O'Regan (The LG Answer Gang)

Serendipity - Linux Today are carrying a story about Open-Xchange Server, the engine of SuSE's Openexchange Server, today - Novell have convinced the owners to GPL it. Since it's Java based, it'll be accompanied by their Java Application Server too.

It'll be available to download at http://www.Open-Xchange.org and http://www.openexchange.com at the end of the month.

They consider it working but the feature set isn't frozen. The version name is "Janus" and they've numbered it 0.7.0 since they hope to cram in a few more features before 1.0.0. -- Heather

Converting a VCD file to MP3

Triyan W. Nugroho (iyan_kid from yahoo.com)

Hello Gang, here is my tips..

There is an easy way to convert VCD (Video CD) file into MP3. What you need are just MPlayer and Lame. MPlayer is used to convert the VCD file to WAV by using the PCM audio output, and then you can convert the WAV file to MP3 by using Lame.

First, you have to convert it to WAV by using the command:

$ mplayer -ao pcm /path/to/vcd/avseq01.dat

MPlayer will play the VCD file like usual, but with no sound. Just wait until it finished. You'll get a file 'audiodump.wav' that you can convert to MP3 by using the command:

$ lame -h audiodump.wav newfile.mp3

Switch -h is used to get high quality MP3 file, but bigger filesize.

Netkit

flavio ()

I just wanted to let you know about a nice project carried out at the Third University of Rome, namely "Netkit".

In a few words, Netkit lets you build a virtual network in order to do all the tests you would like to carry out, with special focus on learning how to use routing protocols and stuff like that. This virtual network is realised launching separate instances of Linux in different xterms - each being a full-fledged Linux box! There are methods to connect those Linux boxes via virtual Ethernets and also to communicate with them from the main host.

Netkit owes 90% of the stuff to UML, aka User Mode Linux, which is a project to let the user launch a Linux Box inside Linux. But I think that they had really an hard time to set up all the environment and create something really usable for these network experiences. Moreover, their website includes a lot of lectures about networking experiences using Netkit. To be honest, when I prepared my exams I found a couple of broken examples but everyone should be able to fix it or to... jump to the next example.

Given the fact that you're probably going to acquire tcpdump logs of the experiences if you decide to give Netkit a try, I also suggest to download and install Ethereal, which is a nice GUI to explore tcpdump sniffs.

You can find Netkit at http://www.netkit.org, more on UML at http://user-mode-linux.sourceforge.net. Ethereal is, of course, at http://www.ethereal.com.

Bye, Flavio.

That's not a bug, that's a feature

Jim Dennis (the LG Answer Guy)
Question by Gary Luker (gluker from southerndata.com)

I found an entry on google regarding a possible bug in bash. I have a script
that does the following.

#!/bin/sh

formatmonth=`date "+%m"` month="$(($formatmonth * 1))" formatday=`date "+%e"` day="$(($formatday - 1))"

when this is run if the current month is 08 it gives me this error. value too great for base (error token is "08")

have you found a fix for this? or know a workaround? thanks for any help!

Gary Luker: MCSE, MCSA, MCP, Linux+, SAIR/GNU Linux Pro

The arithmetic functions in bash (and C and some other programming languages) treat numeric literals with a leading zero as if they are in octal (base eight). Octal digits range from 0 to 7; therefore 08 is not a valid octal number.

Using GNU date you can use formatmonth=`date "+%-m"` to supress the zero padding of the month. That should take care of the problem. According the date man page the %e value is already "blank padded" so it will never be mis-interpreted as an octal number.

-- JimD

answer gang without the spam

Andrew du Preez (dups from neanderthal.ws)
As our readers may recall, The Answer Gang (tag@lists.linuxgazette.net) is really a mailing list where the regular subscribers get all queries and linuxy bits sent through, but it accepts questions and comments from anybody in the world. Of course this means spammers throughout the world email us too... -- Heather

Hello gang,

Here is a lurker's 2c worth on weeding out list spam. With a default set of rules, Spamassassin does a reasonable job of cleaning up my inbox. Recently though an increasing amount of spam sent to the TAG list has been getting past spamassassin. On a mailing list I am willing (more so than for personal mail) to accept the occasional false positive. So I wanted to try running all TAG emails through a stricter set of spam catching rules. Here is the configuration I have tried for the last week or so and found the spam:ham ratio greatly reduced.

A seperate spamassassin config file is used for TAG. From .procmailrc: 

:0fw: spamassassin.lock
* ^Subject:.*\[TAG\]
| spamassassin -p ~/.spamassassin-tag/user_prefs

:0Efw: spamassassin.lock
| spamassassin

And the highlights from ~/.spamassassin-tag/user_prefs: 

required_hits           4

(this is 5 by default) 

score HTML_MESSAGE 3.0
score RCVD_IN_BL_SPAMCOP_NET 3.0
score RCVD_IN_SORBS 1.0
score BIZ_TLD 2.5

(arbitrarily cranking up the score for rules that seem to match the incoming spam)

This setup is working well for me so far (no false positives yet, and only a single junk mail getting through).

The answer gang mailing list is always a good read, and I was glad to find you guys hanging out at linuxgazette.net after being quite surprised at the new structure of the .com site.

'til later TAGsters

--andrew

We are looking into ways of solving it more directly. There'll hopefully be no need for this elaborateness when ( :) ) we do. People are rather busy this month, howwever. -- Thomas
The same problem exists for any decently worldwide mailing list, maybe the -users list from your favorite distribution or major app, so it's still a great Tip! Just beware setting your filtering a little too high, as Jimmy discovers... -- Heather
[Jimmy O'Regan] Heh. I only noticed a couple of days ago that my ISP is running SpamAssassin on my mail before it gets to me. I was wondering why everyone was complaining about the level of spam on the list :) Fortunately my spam is available for a week through their webmail setup, otherwise I'd never have got the contract a client sent me. Now to find a mail provider that doesn't take such liberties with my mail...

More on Linux for low end systems

John Murray (pursang from netwit.net.au)

Just thought I'd point out a piece I wrote a some time ago on getting good performance out of older hardware: http://users.netwit.net.au/~pursang/lofat.html

John

ps. Nice bike Ben! Hope you have as much fun on it as I do on my old GSXR750 :)

And Ben's going to be getting a first person taste of playing with low-end systems soon. Since his laptop has been been in and out of the silicon-lifeforms hospital, I'll be sending him my eldest still-operational laptop for his ongoing use as a proper spare. Thanks, John! -- Heather

Is your sync Hot or Not?

Paul Sephton (paul from inet.co.za)

Dear LinuxGazette

I am the lucky owner of a Palm m515 handheld. One of my frustrations in the past has been that under Linux, I need to establish a PPP connection to synchronise my palm with AvantGo web pages, whilst my preference is to use the normal HotSync button to synchronise the rest of the palm. A frustration, since I wanted the PPP connecttion to establish automatically without my having to do anything, but this conflicts with JPilot Hotsync.

I thought to share the following little bash script with you, which detects in which mode the Palm is attempting to communicate, and establishes a PPP link if that is what the Palm is attempting to do. Otherwise it waits until the Hotsync operation is over and repeats.

I hope that someone finds this useful. By the way, if Palm owners are experiencing trouble with USB drivers in the later (2.6.7+) kernels, I suggest they try 2.6.5. The USB support in that version is excellent.

Paul

See attached paul.palm_smartlink.bash.txt

That's all, folks

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Published in Issue 106 of Linux Gazette, September 2004

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Tux