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...making Linux just a little more fun!
More 2¢ Tips!
By The Readers of Linux Gazette

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

Reading email headers

Thu, 29 May 2003 12:10:21 -0600
Jason Creighton, Ben Okopnik (the LG Answer Gang)

Hey, all -

A while ago, someone asked me how to read email headers to track a spammer (Karl-Heinz, IIRC.) I kinda blew it off at the time (ISTR being tired and not wanting to write a long explanation - sorry...) Lo and behold, I ran across this thing on the Net - it's an ad site for a piece of Wind0ws software which tracks (and maps the track - sooo cuuute!) the path an email took based on the headers. The explanation there is a rather good one; it's pretty much how I dig into this stuff when I get a hankering to slam a couple of spammers (yum, deep-fried with Sriracha sauce... I know, it wrecks my diet, but they're so nicely crunchy!)

The equivalent Linux tools that you'd use to do what these folks have to write commercial software for are laughably obvious. Anyway - enjoy.


The same company puts out a 'traceroute' program that plots each hop on a world map. Cute. Anyway, a google for:


returns a fair amount of articles.

Jason Creighton

Just to make it clear, Ben's talking about some mswin software, and I dunno if he checked that it runs under WINE. But between following Jason's advice, and xtraceroute (http://www.dtek.chalmers.se/~d3august/xt) - our toy for traceroute on a world map - the world of free software should be able to come up with a similar tool. A curious tidbit is that IP addresses whose ranges aren't known to the coordinate system end up at 0,0, the center of Earth's coordinate system... deep underwater in the Atlantic Ocean, near Africa. I wouldn't be too surprised if a lot of spammers live there. Good spear-fishing, fellow penguins. -- Heather

colorful prompt sign

Mon, 19 May 2003 11:44:26 +0100 (BST)
Thomas Adam (The LG Weekend Mechanic)
Question by JK Malakar (cave_man from hotpop.com)

Hi all,

I have seen a colorful prompt sign in RH 9.0 box at a local computer book shop today. but the operator ( who has recently taken migration from M$ to Linux ) has told me that she doesn't know how to do this as the shop has purchased the machine with RH 9.0 preloaded ( & also with that colorful prompt - ;) ). so could some one please tell me how to do this ?

The Linux Gazette knowledge base finds the following article:

which answers your question above :)

About autofs and write permissions for floppy

Thu, 22 May 2003 18:41:09 +0530
Kapil Hari Paranjape (the LG Answer Gang)

I have just configured /etc/auto.master and /etc/auto.floppy. I can now access the floppy without the need to mount it before. But I don't have write access to it. Only root has write access to my floppy.

here are the files I configured:

/etc/auto.master -

/mnt/cdrom /etc/auto.cdrom --timeout=60
/mnt/floppy /etc/auto.floppy --timeout=30

/etc/auto.floppy -

floppy -users,suid,fstype=vfat,rw :/dev/fd0

Did I something wrong? What did I forget?

Thank you in advance for all information you could provide.

Elias Praciano

[Kapil] The automatically mounted filesystems are mounted by the autofs daemon which runs as root and thus a "user" entry will cause files to be owned by "root".
One solution is to use the "mount" command as the user to mount the floppy.
Another solution is if the floppy is a dos floppy to put "umask=666" as a mount option.
[Thomas] I absolutely hate "autofs". I cannot stand it! How difficult can it be to either type: "mount" or "umount"?? Still, each to their own I suppose :)
Am I right in assuming that autofs overrides /etc/fstab in some way? Or is it that you specify "autofs" as the filetype within /etc/fstab ? Either way it shouldn't really matter.
To be on the safe side, I would just make sure that the entry for your floppy drive in "/etc/fstab" is genuine :). By that I mean that you should check that the options:
are present.
IIRC, "supermount" used to do ...
[Jimmy] Oh no! Supermount is evil! Especially for floppies. supermount tries to figure out when the disk has changed, and mostly fails.
[Thomas] If these suggestions still generate the same problem, please post us a copy of your "/etc/fstab".
Ah....I mentioned it because I vaguely remember John Fisk mentioning it in one of his Weekend Mechanic articles a long time ago.
Personally, I don't see why you don't just issuse:
or even better, use "xfmount /dev/abc"
since as soon as you close "xftree", the device is umounted :)
[Ben] I use a series of scripts (all the same except for the device name) called "fd", "cdr", and "dvd" to mount and unmount these:

See attached dvd.sh.txt

I could probably have one script like this with a bunch of links, and use the name as the device to mount, but I'm too lazy to change something that's worked this well and this long.

Thank you all!

Rahul's solution solved my problem. I added myself to the group 'floppy' and changed the mountpoint group to 'floppy'. Then I changed the file auto.floppy to:

floppy -users,gid=floppy,fstype=vfat,rw,umask=002 :/dev/fd0

It's working fine now!

Thank you again. I learned a lot with you.

Best regards!

linux infrared

Tue, 6 May 2003 02:30:55 +0300
klaudiu (klaudiu from gmx.net)

hi. I'm using the circuit described there and it works great in linux with lirc. Another programs that you will probably find useful are:


and to recompile mplayer with lirc support. The circuit cost me ~ 3$ (without the tools that I already had). Hope that I helped. If you need more informations mail-me.

A disabled querent asked about LIRC in general ... -- Heather
[JK Malakar] nice to hear your question on LIRC. yse I have made the home-brew IR receiver which is easy to build as well as cheap also. now I can enjoy MP3, MPlayer, xine etc and even shutdown the machine using my creative infrasuite cd drive remote - ;)
you will get everything at http://www.lirc.org
[Robos] For more infos about how and if you have a question I would say go and ask the source: the lirc page has also a mailing-list where you can surely ask some competent people.
OK, now your question: I have looked at LIRC myself AGES ago and wanted to build that thing too. Didn't do it, mind you (forgot) but I think the hardware and software part were quite well documented. I looked again just now and this here http://www.manoweb.com/alesan/lirc looks really nice and easy. If you think you have problems with homemade stuff try either a TV card (can be had for as little as 50Euros here in Germany), quite a lot of them feature a infrared port already and are quite easy to set up (and you have the benefit of watching and recording TV too ;-) or there are also some irda-adapters for all ports (parallel, serial, even usb) to buy, but I think they are more expensive than a tv card.

On A Slower Computer

Wed, 7 May 2003 13:45:54 -0400 (EDT)
William Hooper (whooper from freeshell.org)
In reference to Help Wanted #3, Issue 90 -- Heather

On a slower computer...

Now, small distros and distros-on-floppy we have by the dozens. But RH 8 compatible? Or kickstart floppies that chop out a bunch of that memory hogging, CPU slogging stuff? An article on keeping your Linux installers on a diet would be keen. Just in time for Summer, too. -- Heather

Definitely check out the RULE project (http://www.rule-project.org/en). They have installers for Red Hat 7.x and 8.0 for low memory and older processor machines. I have personally used it to install a minimal RH 7.3 system on a P75 with 16MB of RAM. Great stuff!

-- William Hooper

[Thomas Adam, the LG Weekend Mechanic] Indeed, William :) I contibute to this project, since I myself use archaic technology :) I'm in the process of writing some docs for installing XFree86 on a 486 with 16MB Ram using FVWM2.
I leave out the byplay of one-downmanship as Answer Gang folk chimed in with the older and slower machines of yesteryear which either gave them their start into Linux or still operate as some kind of server today. The winner and new champeen of Lowball Linuxing is Robos, who wondered why his 486/33 notebook with 16 MB RAM was even slower than its usual glacial self - since all but 4 MB of the memory had come a little loose and X had come up anyway. The winning WM for low end systems seems to be FVWM, with a decent place for IceWM, and a surprise showing for E - provided you use a theme on a serious diet. K is not recommended, and we don't exactly recommend Gnome unless it's a quiet and lazy day for you, either... -- Heather

Interesting take on C/C++/etc. by Jon Lasser

Tue, 15 Apr 2003 20:27:14 +0100
Jimmy O'Regan (the LG Answer Gang)

I think C is used as often as it is because it's the lowest common denominator - write a library in C, you can use it from any other language. It won't be the same for any of the scripting languages until Parrot is widespread.

In case anyone's interested, I came across these links --

Call Perl code from Python

Call Python from C or TCL (easily)

Linux Journal Weekly News Notes - Tech Tips

Tue, 28 Jan 2003 14:55:08 -0800 (PST)
Linux Journal News Notes (lj-announce from ssc.com)

Have Vim Help You Trim

It's always inconsiderate to quote more of someone's posting than you have to in a mailing list. Here's how to bind a key in Vim to delete any remaining quoted lines after the cursor:

map . j{!}grep -v ^\>^M}

where . is whatever key you want to bind.

Your Bayesian Defender -- Train It Well!

If you want to train a Bayesian spam filter on your mail, don't delete non-spam mail that you're done with. Put it in a "non-spam trash" folder and let the filter train on it. Then, delete only the mail that's been used for training. Do the same thing with spam.

It's especially important to train your filter on mail that it misclassified the first time. Be sure to move spam from your index to your spam folder instead of merely deleting it.

To do the training, edit your crontab with crontab -e and add lines like this:

6 1 * * * /bin/mv -fv $HOME/Maildir/nonspam-trash/new/* $HOME/Maildir/nonspam-t
rash/cur/ && /usr/local/bin/mboxtrain.py -d $HOME/.hammiedb -g $HOME/Maildir/no

6 1 * * * /bin/mv -fv $HOME/Maildir/spam/new/* $HOME/Maildir/spam/cur/ && /usr/
local/bin/mboxtrain.py -d $HOME/.hammiedb -s $HOME/Maildir/spam

Finally, you can remove mail in a trash mailbox that the Bayesian filter has already seen:

2 2 * * * grep -rl X-Spambayes-Trained $HOME/Maildir/nonspam-trash | xargs rm -

2 2 * * * grep -rl X-Spambayes-Trained $HOME/Maildir/spam | xargs rm -v

Look for more information on Spambayes and the math behind spam filtering in the March issue of Linux Journal.

NTP: Whose Watch Are We Looking At, Anyway?

It's easy to see what timeserver your Linux box is using with this command:

   ntptrace localhost

But what would happen to the time on your system if that timeserver failed? Use

   ntpq -p

to see a chart of all the timeservers with which your NTP daemon is communicating. An * indicates the timeserver you currently are using, and a + indicates a good fall-back connection. You should always have one *, and one or two + entries mean you have a backup timeserver as well.

Changing Directory the Smart Way

In bash, you can make the cd command a little smarter by setting the CDPATH environment variable. If you cd to a directory, and there's no directory by that name in the current directory, bash will look for it under the directories in CDPATH. This is great if you have to deal with long directory names, such as those that tend to build up on production web sites. Now, instead of typing

   cd /var/www/sites/backhoe/docroot/support

you can add this to your .bash_login

   export CDPATH="$CDPATH:/var/www/sites/support/backhoe/docroot"

and type only

   cd support

This tip is based on the bash section of Rob Flickenger's Linux Server Hacks.

Can't Wait For Mozilla? Speed It Up.

In order to store persistent preferences in Mozilla, make a separate file called user.js in the same directory under .mozilla as where your prefs.js file lives.

You can make your web experience seem slower or faster by changing the value of the nglayout.initialpaint.delay preference. For example, to have Mozilla start rendering the page as soon as it receives any data, add this line to your user.js file:

user_pref("nglayout.initialpaint.delay", 0);

Depending on the speed of your network connection and the size of the page, this might make Mozilla seem faster.

Window Frames My Way, Sawfish Says

If you use the Sawfish window manager, you can set window properties for each X program, such as whether it has a title bar, whether it is skipped when you Alt-Tab from window to window and whether it always appears maximized. You even can set the frame style to be different for windows from different hosts.

First, start the program whose window properties you want to customize. Then run the Sawfish configurator, sawfish-ui. In the Sawfish configurator, select Matched Windows and then the Add button.

Merging Websites With ProxyPass

You can't include web documents across domains with SSI, but with an Apache ProxyPass directive you can do it to map part of one site into another.

ps doesn't need awk

You don't need to pipe the output of ps through awk to get the process ID or some other value you want. Use ps --format to select only the needed fields. For example, to print only process IDs, type:

   ps --format=%p

To list only the names of every program running on the system, with no duplication, type:

   ps ahx --format=%c | sort -u

If you have an ssh-agent running somewhere on your system and want to use it, you can get the SSH_AUTH_SOCK environment variable from one of your processes that does have the agent's information in its environment:

for p in `ps --User=$LOGNAME --format=%p`; do export `strings /proc/22864/environ | grep SSH_AUTH_SOCK` && break; done

This is handy for cron jobs and other processes that start without getting access to ssh-agent in the usual ways.

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/
Copyright © 2003
Copying license http://www.linuxgazette.net/copying.html
Published in Issue 91 of Linux Gazette, June 2003

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