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Linux Gazette Staff and The Answer Gang

Editor: Michael Orr
Technical Editor: Heather Stern
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Copyright © 1996-2002 Specialized Systems Consultants, Inc.

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Before asking a question, please check the Linux Gazette FAQ (for questions about the Gazette) or The Answer Gang Knowledge Base (for questions about Linux) to see if it has been answered there.

• Please help - private email setup
• Video Card and OpenGL
• vpn
• who's linked?
• serial programming in linux
• external modem problem

Please help - private email setup

Hi there

I would like to know how to set up my email on my home network with win98 outlook express and Linux.

I would like to set it up so that I can email anybody else in the house on the network and email via the internet when needed.

Thank You
Cheryl

Video Card and OpenGL

First, some recommendations for a video card (other than Nvidia) that works very well with Mesa and other standard OpenGL apps. I'm considering Ati Radeon, but would like to hear input from others.

Second, I have a TNT2 and run the Nvidia drivers and Nvidia GLX. I have had random success compiling OpenGL based programs in the past. Today, I learned that Nvidia's headers are not placed in /usr/include/GL so as not to override the defaults that are installed with your system. I'm not sure whether this was a recent addition to the Nvidia readme, or I just missed it all those times in the past. I run slack 8.0 and often create packages from the sources I compile to be used on other systems. If I switch to using the nvidia OpenGL headers will this cause problems with systems not running Nvidia GL?

Thanks for considering my issues.

vpn

Multiple translators offered one; I have selected Felipe's as being the most faithful to the original text.

Anyone who feels inclined to answer this, it's okay to answer in English, just copy our translator so the querent can get a copy in Spanish, and the Gazette so I can post the follow-up in a later issue.

Alternatively, FreeS/WAN has been growing in popularity, and anybody who has an interest in writing a "setting the FreeS/WAN VPN up from scratch" article, possibly even comparing the effort against other tries for your own VPN (virtual private network) setup. would surely earn a great many virtual beers.

Normally the gang razzes people who want us to do their homework for them. But the truth is that the most useful thing the Gazette has to say for this subject is that you can buy one from SuSE (News Bytes, issue 74). See our author guidelines if interested: http://www.linuxgazette.com/faq/author.html

Make sure to refer to current FreeS/WAN docs:

http://www.freeswan.org/freeswan_trees/freeswan-1.95/doc/index.html

les agradeceria mucho que la información fuera en español

Hola quiero realizar una trbajo para la materia de redes me pueden ayudar gracias como creo una vpn con dos pcs con suse linux 7.0 y freeswan 1.4 como configuro los archivos ipsec.conf e ipsec.secrets, ademas quiero ver si funciona la conexión haciendo ping y telnet con y sin cifrado de una pc ala otra y usando ehterreal como se si ese paquete esta cifrado o no

quiero hacerlo usando primero direccion fija y luego direccion dinamica

primero con direccion fija

la pc1 tiene la ip 1.2.3.225 y la pc2 la ip 1.2.3.226 y el gateway la ip 1.2.3.1 como configuro esto con freeswan.

segundo con direccion ip fija en la pc1 y dinamica en la pc2

la pc1 tiene la ip 1.2.3.225 y la pc2 la ip x.x.x.x y el gateway de la pc1 con la ip 1.2.3.1 como configuro esto con freeswan.

ESQUEMA DEL LABORATORIO A REALIZAR

COMO HAGO PARA CONFIGURAR ESTOS ESQUEMAS CON FREESWAN

ESQUEMA PARA LAS DIRECCIONES IP FIJAS

      __________
      |INTERNET|
      ----------
          |
          |
       _______
       |modem|
       -------
          |
          |
        ______
       |router| ip=1.2.3.1
        ------
          |
          |
      ________
     | switch |
     ----------
        /     \
       /       \
      pc1      pc2
ip=1.2.3.225   ip=1.2.3.226

ESQUEMA PARA LA DIRECCION IP FIJA DE LA PC1 Y DINAMICA PARA LA PC2

      __________
      |INTERNET|
      ----------
          |     \
          |      \
       _______    PC2
       |modem|    IP=X.X.X.X
       -------
          |
          |
        ______
       |router| ip=1.2.3.1
        ------
          |
          |
      ________
     | switch |
     ----------
        /
       /
      pc1
ip=1.2.3.225

Translation

Hello:

I am doing my homework for the "Networking" class, if you can help me I'd appreciate it.

How do I create a VPN with two PC's using Linux 7.0 and Freeswan 1.4 ?

How do I configure the files ipsec.conf and ipsec.secrets ? Besides, I want to find out if the connection works using ping and telnet with and without encryption from a PC to the other and, lastly; using Etherreal, how can I verify if a packet is or is not encrypted. ?

I want to do all this using first fixed IP addresses and later on dynamic IP addresses; let me show you the example with a fixed IP first:

PC1 has ip 1.2.3.225 and PC2 has ip 1.2.3.226, gateway has ip 1.2.3.1. How do I configure this with Freeswan ?

Second, with fixed IP on PC1 and PC2 has IP x.x.x.x, gateway remains the same with ip 1.2.3.1. How do I configure this with Freeswan ?

The LAB DIAGRAM to comply with is as follows: How do I make to configure all this with Freeswan ?:

DIAGRAM FOR FIZED IP ADDRESSES

[first diagram shown above]

DIAGRAM FOR FIZED IP ON PC1 and DYNAMIC IP ON PC2

[second diagram shown above]

who's linked?

In Issue76 [Heather] mused....

...a way to ask a program which libraries it is potential-linking as well as dynamic-linking to, ...

Paul Ahlquist answered with this basic Tip:
If your system lib's deity of choice is "ld", then "ldd" should answer the burning question.

Hmm, I guess I wasn't entirely clear what I was really asking:

dynamic-linking: as in not static, see 'ldd'. Binaries which are dynamically linked will fail if the library is not present. This is what almost every program on the planet does, because nobody wants to waste the memory space for extra copies of glibc, at least without a good reason.

potential-linking: as in "if this library is not present I won't shed a tear, but if it is I'd like to use GTK please", see ... ?

Such a binary would have to somehow check that the library was somewhere it had access to, then use dlopen() to request loading the one it found. 'strings' might reveal it, but I'm not sure how reliable it is for this, thus the question.

I suppose not very many people code potential-linking into their programs, so it's not the first thing that leaps to mind; still... since I mention "dynamic linking" in the same sentence as this other sort, one would have thought I meant something different?

Anybody know a reliable way to ask a program about the library-load requests it hopes to make? (as opposed to has to make)

But while I'm at it, another question: if anyone knows a reliable way to ask a binary which libraries it has been statically-linked to, that'd be nice too. 'strings' usually does reveal this, but... anyone know how reliable or complete it is?

serial programming in linux

Hi, dear Heather,

This is Clement from University of Virginia. I am working on a project involving serial port programming under linux. I am new in the linux world and don't quite know where to start.

I have read most of the Serial-HOWTO online but none gave me the information that I needed.

I came across the linuxgazette.com and saw your discussion on serial programming. I am wondering if you can give me some pointers here. Any help will be greatly appreciated.

Things that I am trying to do: I want to connect the 9DB RS232 on my linux box to a Ericsson Bluetooth module. At the same time, I want to use one of unused pins, RI or CD pin for instance, to serve as a trigger to another circuit. Therefore, I need to be able to turn that specific pin to high and low at desired time.

My questions are:

1. How can I control a specific pin?
2. What are the header files I shall be looking at? (I have been using termios.h and fcntl.h along with some other files. However, I found it very hard to understand. )

Thank you very much. I am looking forward to hearing from you.

Clement Song

external modem problem

Two questions - one hardware matter, probably not linux. The other, a good question, especially in the general form, and would make an excellent article.

I have an V90/K56flex external modem that I use to connect with my ISP via a dial-up line. The modem obeys the Hayes command set. Now the point to note is that I have make a long distance call or STD call as we call it here in India, to establish a connection. This might seem a very expensive thing to do but I have no other option. Now each time I establish a connection using kppp the modem waits for almost 40secs inbetween transmission of packets whose duration is approximately 5secs. Thus after establishing a connection the modem activity is as follows:

40secs-no TD/RD, 5secs-TD/RD, 40secs-no TD/RD, 5secs-TD/RD, ........

Is this normal or is something wrong? Do you think there is something wrong with some configuration somewhere?

I suspect that there is something wrong... but it's most likely not configuration, at least not software-wise; it's either your modem, or your ISP.

The same thing happens in Windows too.

So... it's got nothing to do with Linux, then.

Try using another modem, preferably with a different computer, from your location. If the problem persists, it's your ISP. If it goes away, it's your computer and/or modem.

Thanks for your prompt reply. I have been trying out your suggestions. Unfortunately there aren't any Linux boxes in my locality. Changing the computer does not seem to improve the performance of the modem. As for trying out another ISP, I don't have any options.

Are there any parameters in the Hayes set that could affect the TD/RD rate of the modem?

Finally may I add another question? Could someone point me to an article or HOWTO about setting up qmail in a stand-alone home computer for transfering mail to an ISP mail server over a dial-up line. The documentation with the package isn't of much help.

-- amitava maity

• Modules in /boot bad idea?

Modules in /boot bad idea?

I considered putting this in TAG - it's a mite large for Tips - but since I've given the nod to our readers rather eloquently, I put it here instead. Thanks to all our fans -- Heather

Hi,

I was disturbed to read Heather's suggestion to put kernel modules on a /boot partition ("booting multiple linux distributions" TAG #5, Issue 76). My question is, why would you bother to do this? It seems error prone to me.

Because on triple boot systems where all three are Linux, it means they can all use the kernels. As soon as the symlinks are established it works marvelously - personal experience.

I didn't recommend it as the only thing one could do; just a possibility among many, and part of an answer to a question asking "which partitions can be shared?"

To summarize: /tmp, swap, and ... if you are careful ... /home and /boot. If "error prone" are the kind of words that scare you from even trying something, or learning what "careful" means for your context, you should share neither /home nor /boot.

Unlike the kernel itself(1), modules are read through the filesystem so their visibility does not depend on which partition they are on. In fact, putting them on /boot means they are not available until /boot is mounted, which is noticably after the kernel is loaded. This complicates the boot process by adding a dependency that /boot must be mounted before any modules are loaded. (Normally /boot doesn't need to be mounted at all unless building kernels or modifying lilo).

The kernel wouldn't load sanely if a module were needed to mount /boot successfully. In my philosophy /boot is always mounted read-only because I keep its symbol map there, and a copy oof the .config I used to make it.

But of course, I build kernels all the time, it's something I do for clients as well as myself.

Further, there is more chance of causing collisions between distros in the modules tree. Presumably multi-boot systems use a separate / partition for each distro. This means that each will have its own /lib/modules tree with subtrees for each kernel version. Moving each of these to /boot means that each distro shares modules with the others. I would guess that usually that won't be a problem, but if it is then it would probably be hard to debug.

kernels are not distro specific and anybody who tries to tell you so needs to be whapped a good one. The only thing about them that even approaches it is that some distros are kind enough to package kernel-and-module kits for you. For each distro:

ln -s /lib/modules /boot/modules

There, now they are all happy. "complicated" ? no. "error prone" ? only if you're foolish enough to trust a packging system to remove kernels for you. The only one I even let try is debian, and then only when I have known good kernels that LILO knows about already.

mounting /boot earlier in a startup sequence may be needed for some distros. If one such distro is among your dual-or-more Linux mix, then I heartily recommend initrd so you'll never need to worry about that.

But it works fine for mixing SuSE with RedHat, as of a few revisions ago on both of them.

The only advantage I can see to putting modules on /boot is being able to share disk space for them between distributions.

Gawd yes.

But the complication of having several distros mucking with each other's modules seems to outweigh that.

I don't let package managers "muck" with my kernels and you shouldn't either. As soon as you know enough about what you want in kernels to care this deeply then you should not be worrying about packaged kernels anymore - roll your own, make it match your real hardware, and use the same, well behaved kernel no matter which userland you select to run today.

I don't follow Heather's assertion that running a 2.4.x kernel package and a 2.5.x kernel built from source is simplier with this scheme - the modules are already kept separate in /lib/modules by separate version directories. Am I missing something more significant?

Ohhh, you had some sort of delusion that I was taking (for instance) 2.2.18 modules, 2.4.12 modules, 2.4.19-pre3 modules, and throwing them all in one directory together? That certainly wouldn't work.

Certainly this method can be made to work, but I would guess it is only for sophisticated users with specific circumstances. That's not typical of readers of The Answer Gang, is it?

There is no such thing as a "typical" reader of The Answer Gang. We get complex questions, simple questions, complex phrasings of simple questions (ugh), and simple phrasings of complex questions (yay!). We get discussions about the deep magic of programming and how to properly use the "date" program. And everything in between.

If you assume that by having a worldwide audience we are always going to play to the dumbest possible reader, sorry but that's not so. Every member of the Gang will answer any given question their own way; when all is said and done, I'm mostly just turning a conversation originally written "radio reciever" style (everybody gets their say in big paragraphs) into a more readable "group conversation" style.

In my case, by the time someone is considering triple booting anything, they are sophisticated enough to consider options such as these that I have used.

But a good point to bring up is: distros do change over time. Something that worked very nicely a year ago may be all wrong now, or very complicated now, or just have a much easier answer at hand now. As with maps, the picture and the advice are not the territory itself.

Dave

(1) Boot loaders like lilo need to load the kernel as disk blocks using bios calls. There was a period when disk sizes were large enough that the bios could not address the entire disk. On such a system, it is convenient to make a /boot partition at the beginning of the disk so lilo will be able to load the kernel. On smaller disks or with newer bios, this work around isn't necessary.

But may be handy if you have a disk disaster, to know that kernels were nearer to the front than the back of the drive.

Of course if you fear this, give up on LILO and switch to a boot loader which will seek out kernels wherever they happen to live on the disk. (Advice good for PC users only. Sparc's SILO already does that.)

P.S. /lib/MOVING can be deleted safely before rebooting. Although directory information will be removed immediately, open files will not have their inodes freed until they are closed. That's why /lib/modules can be replaced by a symlink while the system is running in the first place.

If one is going to be complicated, it pays to keep an eye on the details. In this case it cautions one, and may even comfort one, that you have not deleted the original directory until you actually make that choice, as a sysadmin, and after your new boot sequences are tested.

Tom's rootboot is good to have around too.

I don't let package managers "muck" with my kernels ... roll your own ... and use the same, well behaved kernel no matter which userland you select to run today.

Ahh, I see. I had assumed you had different kernels for different distros but of course the first time I found myself building the same kernel on two different distros I'd realize they should be shared. I guess I don't use enough different distros at the same time to run into that, which is why I asked about it.

Thanks for enlightening me.

...no such thing as a "typical" reader of The Answer Gang. ... more readable "group conversation" style.

Well, I appreciate that immensely. It's always nice to have something intriguing to think about even though the overall topic may be well known (if not to beginners). You do a great service to your readers when you throw in a little something over their heads. It gives them something further to explore rather than making them think everything has been said (never the case, of course).

Count me a fan!

Dave

• Re: Job Announcements
• Another round in the spam war
• Now we're trying to look Really Cool rather than just plain

Re: Job Announcement

We got a handful of a requests for job postings this month. Here's the policy.

LG doesn't publish job listings because they are temporary in nature.

LG is for more permanent material. Job openings change so frequently that by the time the next issue is published, the job could well be filled. And if we publish one job listing, we'd have to publish them all.

We do not currently have any other place to post job listings, so I suggest you try another site such as mojolin.com, dice.com, monster.com, etc.

-- Mike Orr

Another round in the spam war

...after some effort to get Mike his article submission...

PS: I'm trying a roundabout route to get this email to you; it seems that your email server doesn't like my ISP's email server and has rejected my last two attempts at emailing this to you. Since my ISP is a large Canadian provider, it may take some time to persue and correct the mutual email problems, and in the mean time, I'm trying this end-run to get the article to you.

Our sysadmin Dan Wilder verified we're refusing mail connections from sympatico.ca because they're refusing mail connections from us. Or rather, the connection times out when we try to reach them. This causes a load on our mail server because the message sits on our outgoing queue for several days as it keeps trying to send it. Ask your ISP whether their mail server is blacklisting ssc.com. If not, we'll turn off the lock. But you may mention that we're still unhappy about the large amount of spam we receive from sympatico.ca.

Setting up a mail server in send-only mode is a common tactic by spammers. Not saying that sympatico is doing this, because they need to receive mail for their users. But that's why we block out any site that sends us mail but consistently refuses connections from us. They do it because those "1 million e-mail address" lists have a large number of obsolete addresses that cause bounces, and their mail server couldn't handle the bounce traffic. (Or maybe it could, but that would slow down their spam-sending. ) Which is exactly what's happening: sympatico users send spams to fifty or a hundred accounts here that have been deactivated or never existed, and our mail server bogs down trying to send back the bounce messages--which they refuse. But probably what sympatico has is a misconfigured mail server. Our error message tells who to call if their postmaster cares. From /etc/postfix/access:

sympatico.ca 550 You refuse our connections so we refuse yours: 1-206-782-8808 if you have corrected the problem.

I'm cc'ing your sympatico address with this letter to see if it gets through.

-- Mike Orr

how we're trying to look Really Cool rather than just plain

Please see the Back Page for details.

This page edited and maintained by the Editors of Linux Gazette Copyright © 2002
Published in issue 77 of Linux Gazette April 2002

HTML script maintained by Heather Stern of Starshine Technical Services, http://www.starshine.org/

• Hard Disk: BadCRC errors from dma_intr on bootup...
• [LG 76] wanted #7 lockups after upgrade
• [LG 76] mailbag #2 make install
• xtraceroute question in the Mailbag
• .dat files
• information on catching a packet through network
• debian pictures
• [LG 76] wanted #4 DHCP
• Dial in access with PPP
• DOSEMU Help!!
• Dos linux partition access
• INSTALLING RED HAT 7
• [TAG] Recompiling of a linux kernel
• [TAG] Linux NEC printer problem
• Memory Mapping
• what is NET4?
• NFS mount permission
• Mandrake 8.1 and nVidia
• Don't Like Your ISP's Choice of Name Servers?
• share the directory
• Machine Check Exception!
• [TAG] two monitors
• winux?
• xfree86 4.2
• Linux Journal's Weekly News Notes Tech Tips
  • E-mail stats via Python
  • Tech Tips: Hotkeys
  • Imposing a minimum font size on Mozilla
  • subscribe to Linux Journal's Weekly News Notes

Hard Disk: BadCRC errors from dma_intr on bootup...

I had this exact same problem.

Try disabling HDD S.M.A.R.T. in the BIOS. Worked for me. Dunno why, though!

-Chris

[LG 76] wanted #7 lockups after upgrade

I would still suggest ram, even if it didn't cause problems before. Everything has to have a first time failure. I had a ram board that would work merrily along for days before suddenly locking up. I presume it would have shown itself sooner had I changed to something needing more ram to work well.

Secondly I'd look at heat. Is this machine in a warm place? A hot CPU is a grumpy CPU. Video players can put a strain on them.

Third, power supply. RH7.2 requires more resources than 6.2 required. More resource needs will put a strain on the power supply. Not necessarily a likely problem, but the symptoms certainly suggest it as a possibility.

Video cards can do this, as can sound as you suggested.

Finally, I've had problems with this myself, all caused in the past by KDE, gnome and screensavers. I have a friend that turned of f the screensavers in gnome and ran xscreensaver and his crashes stopped. He did the same in KDE and, again, crashes disappeared. This would also suggest a relationship between video boards, libraries, compile-time options, etc. Since most people use "outta the box" RPMs, the compile options aren't necessarily optimized to work with their other hardware.

Alan Brady

[LG 76] mailbag #2 make install

You're right

That's after the make that you must become root (you need to be root to install the files but not to compile them

xtraceroute question in the Mailbag

There's a program in Debian unstable called xt (xtraceroute). It's supposed to plot the traceroute path on a picture of the earth. However, it doesn't seem to have enough location coordinates in its database to do anything. Has anybody used this program? Did you have to enter your own coordinates for all the hosts you traceroute from and to?

I am not subscribed to the list, or however it works, so please forgive me if this is going to the wrong adress, I did my best to accertain that this was the one. In anycase, I believe I can give an answer.

Many routers, and other end nodes, can be configured to know what thier geographical location is in longitude and latitude coordinates. This allows diagnostic information, and the curious, to find where on earth a particular device is located. However, network administrators may be too lazy to look up and configure such information, and/or not really care to. There really isn't any good reason to do this, except for satisfying the curious people.

.dat files

does linux support the playback of .dat files and what are the recommended (easiest/most powerfull/stable) player

Hi!

Well, probably you mean vcd (video-cd) data files (there is the actual movie data in there). If anything is related in some way to movie, always take mplayer (mplayerhq.hu). I follow their mailing-list closely and mplayer plays (nearly) every movie format you throw at it, for example *avi (divx), mpeg1/2, divx5, fli, film (from sega game cd) roq (id film sequences, for instance from quake 3 or rtcw), qt kinda, rm kinda, asf streaming even, wmv ....

So, take a look, it works great.

Robos

information on catching a packet through network

hi,

we are working on a project which involves playing with the network for capturing the packets. Right now we are stuck because we only know about SKBUFF i.e. socket buffer.But we are not able to track any detailed information about how to use it. Everywhere there is a brief introduction to the SKBUFF functions but not on how to use it.

If your team can help us in directing to a site or some other source through which we can capture each & every packet traversing through the network into our own Queues(userspace) it would be a great help to us.

We would be very grateful to u if u can help us in this matter.

Thanking you.

Regards Bharath Kumar

Hi Bharath Kumar,

I'm not sure about the SKBUFF functions, but you have at least three tools available for just viewing network traffic and saving the data to files for later playback.

You have tcpdump, ethereal, and tethereal. Ethereal gives you a GUI-based package where you could collect packets and view the stuff later with a detailed dissassembly of the packets. Tethereal gives you a text based equivalent version of ethereal.

Tcpdump is the old standby program which is yet another command line application. You get dumps of packets to the display, you get filtering capability, and you could save the dumps to a file. I should mention that ethereal also lets you filter the data. I have not tried filtering with tethereal.

Regards, Chris Gianakopoulos

man tcpdump, and the related software, like the pcap packet capture library. You might find that just letting tcpdump will be good enough for you; if not, the sources will likely serve as a hint.

Cheers, -- jra

debian pictures

i have a cd of a Debian distrobution, is it posible to find the background folder and copy it to my mandrake 8.1 box, so that i can use the debian swirl as a background to Gnome and KDE,

thanks from elliot

I'm sure that it's possible, if not very easy. You would have to find the file in question and copy it from the CD to the appropriate dir of your mandrake system. The trick is finding the file. I don't use kde or gnome, so I can't be of much help with very specific information. However, if you have midnight commander installed (if you don't, then you should!) you can probably get the file you need - it will require also having "dpkg-deb" installed. That will allow you to open the Debian pkg file where the kde / gnome backgorind of interest is, and copy it to your system. It is probably a little beyond the level of neophyte though, so would require some reading up & digging for info on your part as to the whereabouts of those files under kde / gnome.

-- John Karns

[LG 76] wanted #4 DHCP

Answer by Eduardo Perez Esteban:

Yes, you can tell DHCP to answer requests coming only from a specified set of MAC adresses. Use the "deny unknown-clients" flag for this.

Note that this is a very weak security enhacement: an attacker only needs to know the network address you are using and try several IPs until he finds an empty one.

Regards, Edu.

Answer by Bill Barber:

This would be my suggested entries to /etc/dhcpd.conf

The xx:xx:xx:xx:xx:01; represents your MAC addresses and the belief would be if the MAC address is not in the list, it would not get an assigned IP address, I do these type of entries for my servers, but I also have non-MAC-specified hosts, so I don't know if it would refuse with just that. I think if you dropped the subnet portion, you would get an error.

See attached dhcpd.conf.txt

Dial in access with PPP

I am trying to setup a dial in connection to pc's in the field. they = have dedicated phonelines to them and i can't get PPP to setup correctly = on them. I have failed in every attempt. can you help me with this.

What tools are you using? What have you tried? What error messages are you getting? How are the PCs set up?

-- Neil Youngman

And you could have a look at mgetty from mgetty+sendfax -- does what you want, i.e. answering the phone, deciding if it's a data connection and initiating a login process (and pppd if you want, look at auto pppd).

K.-H.

DOSEMU Help!!

Alright I am getting close with running DOSEMU but I have run into a glitch. It loads and runs MSDOS but I can't get Himem.sys to install properly.

I have added the proper lines to my msdos config.sys file. Here is what it reads:

DOS=HIGH,UMB
BUFFERS=30
FILES=50
STACKS=0,0
LASTDRIVE=Z

device=c:\dos\himem.sys
devicehigh=c:\dos\emm386.exe ram

You mean that this is the adequate setup for your applications under `true' ms-dos, right? If so, can you check what the `mem' command says once you have booted your machine into a real-mode dos session? It'll be a good starting point to determine what your memory requirements actually are (see below).

Then the config.sys within freedos reads:

DOS=UMB,HIGH
lastdrive=H
files=20
rem buffers=10
device=c:\dosemu\himem.sys
devicehigh=c:\dosemu\emm386.exe ram
rem devicehigh=c:\dosemu\cdrom.sys
shell=c:\command.com /e:1024 /p

But when I start dosemu I get the following messages:

HIMEM: DOS XMS Driver, Version 3.10 - 09/30/93
Extended Memory Specification (XMS) Version 3.0
Copyrigth 1988-1993 Microsoft Corp.

ERROR: An Extended Memory Manager is already installed.
XMS Driver not installed

Yep. This is caused by the `himem.sys' line for sure.

Since an extended memory manager is already integrated in dosemu's core, you don't actually need `himem.' All the necessary XMS functions are available upon startup even without it -- hopefully.

EMM386 not installed - protected mode software already running.

The original `emm386' won't run if the CPU is not in real-mode (as opposed to protected/virtual mode). Linux being run in protected mode, this is the reason why an alternative `ems.sys' is shipped with dosemu. Normally this replacement expanded memory manager should provide the same facilities to dos programs as its MS counterpart.

The largest part of EMS memory management code is probably hidden deep within dosemu itself (ems.sys is only a few hundred bytes in size!) Advantage: more memory available for dos programs

I know emm.sys comes with DOSEMU but I need to load emm386.

Mmm... What makes you think so?

AFAIK the only tunable settings regarding the memory management in dosemu are:

• The amount of `conventional' memory seen by dos (normally 640 Kb).
• The location of the EMS page frame in (low) memory.
• The amount of memory to reserve for XMS, EMS and DPMI respectively.
• A set of locations/ranges of hardware RAM zones (none by default).

All this is controlled by the dosemu built-in memory managers.

By using the output of the abovementioned `mem' command in a `true' dos session, you should be able to set up the relevant parameters in your dosemu.conf file and get your application programs happy; e.g.

C:\>mem

Memory Type        Total        Used        Free
----------------  --------   ---------    --------
Conventional          640K        69K       571K
Upper                  90K        40K        50K
Reserved              384K       384K         0K
Extended (XMS)     97,190K       598K    96,592K
----------------  --------   ---------    --------

Total Expanded (EMS)                   32M (33,947,648 bytes)
Free Expanded (EMS)                    32M (33,554,432 bytes)

Largest executable program size      571K (584,672 bytes)
Largest free upper memory block       50K (51,152 bytes)

In your dosemu.conf file the corresponding settings would be:

$_dosmem = (640)        # in Kbyte, <= 640 (default)
$_xms = (98304)         # in Kbyte (instead of the default 1024 Kb)
$_ems = (32768)         # in Kbyte (instead of the default 2048 Kb)

In fact you should not give such high values to dosemu. 16 megabytes for each (or even less) may still meet your actual requirements. Begin with large enough values then decrease them and retry until you find the optimal setup.

If this method doesn't succeed, well... I don't know. Maybe the apps you're trying to run do not comply with the EMS official specs. Aren't there Linux ports or equivalent programs?

Oh, and don't forget to replace the himem and emm386 lines in your config.sys with:

device=c:\dosemu\ems.sys

(or devicehigh=...)

Help would be...um..helpful

Indeed So I hope this does.

...Didier found a more helpful tidbit to throw in...

Begin with large enough values then decrease them and retry until you find the optimal setup. .

And in fact the system won't let you do that unless you increase the kernel SHMMAX setting (amount of IPC shared memory available for user processes) as well. The Linux kernel (2.4.x) default value is 32 megabytes. In the above example you would need at least 96 + 32 = 128 Mb of shared memory.

For in such a case, dosemu would complain about being unable to satisfy the user's memory settings (see the boot.log file). Assuming you have enough RAM in your system, you'd have to issue (as root) a command like:

echo 134217728 > /proc/sys/kernel/shmmax

The actual value -- expressed in bytes -- would depend on the total amount of memory (XMS + EMS + DPMI) set up in your configuration file.

However strangely enough the 2.2.x kernel doesn't seem to impose such restrictions (although the /proc/sys/kernel/shmmax entry is present).

Regards, Didier Heyden.

Dos linux partition access

Is there any dos program that would allow dos to read and write to a linux partition? if so is there a free version out there?

Thank You
Brian Binkley

Hi Brian!

There is "explore2fs", but thats under win, don't know if it runs under dos too: http://uranus.it.swin.edu.au/~jn/linux/explore2fs.htm

-- Robos

The owner has a big fat (no wait, ext2 ) WARNING: that write support is at the moment very, very risky. Which I guess puts it in the same boat as Linux' NTFS support...

Peter van Sebille wrote FSDEXT2 as a standard MSwin filesystem driver (Jay found it too. "Hi Jay!" she says waving cheerily), but it does not write at all; he had "0.16" stable and "0.17" dev (the dev one under GPL)... but another fellow Gerald Shnabel seems to have taken up the torch, at least enough to make it work on his win98 systems, and released version 0.163. For you license fans out there, he derived it from the license-unknown 0.16, but explicitly put copyrights and announced that it's under the GPL: http://www.schnabel-online.de/fsdext2.html

Way back in 1995 the Linux Gazette mentioned ext2tool, and since I found it mentioned in the dosutils directory on my SuSE 7.3 stuff, I guess the thing still exists. Too bad SuSE only provided the sources (eep) so it makes me really wonder how long it's been since they were last tested...

-- Heather

INSTALLING RED HAT 7

I am trying to automatically install redhat 7. The message I keep getting is not enough disk space (there is). Do I need to partition the disk? I want a dual boot system my current op is windows xp and the filing system is ntfs. If I need to partiton the disk is there some very, very, very simple info on how to do it available.

Yes you need at least one partition for Linux, preferably several. There's some info at http://www.linuxdoc.org/HOWTO/mini/Linux+WinNT.html

If you don't want to reinstall from scratch your best bet is to buy/borrow a copy of PartitionMagic and use that to shrink your XP partition and make space for Linux partitions.

It is possible to run Linux off just one partition, but well chosen multiple partitions make it more robust, as filling one partition won't bring the whole system down.

As a minimum you need a root partition and it's rare to run Linux without a swap partition as well. There are some recommendation for partition sizes in the Answer Gang Knowledgebase at http://www.linuxgazette.com/issue58/tag/11.html and you may also want to browse http://www.linuxgazette.com/tag/kb.html#fs

Thanks and I look forward to hearing from you

My pleasure, but please turn off that HTML crap in your email.

Sincerely
Neil Youngman

[TAG] Recompiling of a linux kernel

Hi! All

Does anyone know of a linux site which gives a brief description of each & every option given in the "xconfig screen" while recompiling a linux kernel.

Besides the help button next to each of them which have useful information in most of the cases -- no I don't know websites having a full list. Also the ones difficult to choose are not the standard options which have very helpful entries in the "help" anyway. Mostly the problem is with short lived hacks which are there for some few kernel versions and disappear again. It would be rather difficult to keep a website up to date.

A look into the kernel source is always helpful (for example one could search recursively through all *.c and *.h file in the kernel tree where the OPTION_FLAG is actually used and have a look in that file. Some of the sources are extensively commented, especially the details of some hacks or the consequences of using/not using certain options. I remember lot of configurable (and documented!) options directly in the source of the aic7xxx SCSI module which now gradually moved over to xconfig entires.

There are webpages (like www.kernel.org) where you can have annotated kernel source, browse it and have direct access to the changelog files which also are helpful in some cases for choosing kernel options.

K.-H.

[TAG] Linux NEC printer problem

Sir,

I have been unable to print with my Printer (NEC PinWriter 5300) I am using RH 6.0 and my printer is an (old) NEC pinwriter. I'll already email the manufacturer of this Printer then they told me used Epson LQ850. I use the Epson LQ850 driver with Windows. Where i can get the postscript of this printer. I checked all the How-To but I am still clueless. Could you please help?

I recommend visiting http://www.linuxprinting.org

I cant find the specific pinwriter, but the epson LQ850 is there, reported as working perfectly with the ghostscript driver lq850

see:

http://www.linuxprinting.org/show_printer.cgi?recnum=63360

So you have to setup your printing with the lq850 driver. To check if it's supported by your ghostscript run:

gs --help

it seems not to be compiled into the standard ghostscript (coming with SuSE Linux [67].?) so you may have to recompile ghostscript and put the driver lq850 in the right makefile/includefile. See the README and INSTALL coming with ghostscript.

K.-H.

Memory Mapping

Hi friends,

I have tried using the mmap function in linux and succeeded.

The Info Pages say about a particular flag in calling mmap.

`MAP_ANON'

This flag tells the system to create an anonymous mapping, not connected to a file. FILEDES and OFF are ignored, and the region is initialized with zeros.

Anonymous maps are used as the basic primitive to extend the heap on some systems. They are also useful to "share data between multiple tasks without creating a file".

I want to know how 'mmap' can be used to "share data between muliple tasks without creating a file" as is said above.

See section 14.9 of "Advanced programming in the Unix Environment" by W Richard Stevens. To summarise briefly, if this is used together with MAP_SHARED, this region can be shared by the creating process and any child processes created with fork. According to section 12.9 memory mapped regions are not inherited across an exec.

Neil Youngman

what is NET4?

Someone told me that Linux uses a TCP/IP suite called Net4. What is that? for example, how is its TCP different from TCP-Reno?

Hi Ming,

Linux Net4 is based on Swansea University Computer Society NET3.039. The TCP/IP protocol suite, TCP-Reno is Berkeley code (the BSD stuff). It is my belief that Net4, although it may be influenced by other protocol suites, was written from scratch (other than being derived from NET3.)

Regards, Chris G.

NFS mount permission

I have an NFS mount problem here. I am doing all this as root. I have mounted a remote nfs filesystem on a directory on my machine. I want that directory to be accesible by a particular user on my system. For that after mounting to that directory I tried to make that user the owner of the directory, but it is not happening ("error : operation not permitted")

What is the correct way of doing this? sree

Hi Sree!

I don't know for sure (like most of the time) but something along: -specifying user-pid in /etc/fstab behind the nfs-mount -adding that particular user to a group that can read the drive I've done the upper one some time ago, it worked, but now I forgot ... and am lazy right now

-- Robos

ISTR that you can't do this sort of thing remotely. If you want to muck about with ownership you need to do it on the exporting server. I forget the details but essentially you are only root for local filesystems, thus limiting the damage that remote hosts can do on exported filesystems.

-- Neil Youngman

Mandrake 8.1 and nVidia

we have all the linux gazette on the school intranet and from reding the artcles i find myself hooked on linux, i have one question though does installing Nvidia drivers for a Geforce 2 GTS overwrite Xfree 4.0.? or are drivers and xfree different as i would like to play quake and unreal on mandrake 8.1 Kernel 2.4.? but xfree 4.0.? is only 2D and xfree 3.36 with experimental 3D is very Poor. HI,

The nvidia drivers are just modules that plug into XFree86-4. Installing the nvidia drivers will not overwrite the Mandrake X drivers.

The reason being... the nvidia drivers are closed source, and there is only a binary distribution available from nvidia. There is an opensource project that writes open drivers (The ones installed by Mandrake)

In the XF86Config-4 file (edit with care in mandrake) the drivers are named "nv" for the open source ones and "nvidia" for the closed source ones.

The closed source drivers are far superior with very good 3d support. You will not win any brownie points from RMS for infecting your system with these.... but boy they run.

On the nvidia web site there is RPMs compiled for Mdk8.1, they work very well.

The "nvidia" drivers need a kernel module called "NVdriver", that has to be compiled agains the kernel headers for your current kernel. This is a non event with a standard Mandrake install, if you have downloaded that spunky new 2.4.18 kernel and tweaked it... download the source release for the NV_Kernel module from nvidia and recompile against the new kernel headers.

Some of these steps are tricky, if you are unsure, let me know... I have done this a couple of times.

Kind Regards Johan H.

Don't Like Your ISP's Choice of Name Servers? A 2 Cent Tip

I use a dialup account with my ISP. Many times, I get a good connection with respect to data rate. But, my IP traffic throughput is not so good. For example, several seconds to reach my favorite sites with ping

One cause was the name servers that were handed to my system during the PPP authentication phase (I know -- that's really DHCP, not PPP). I use wvdial for my Internet dialer. Here's how to force your own choice of name servers.

In your /etc/wvdial.conf file, make an entry like this:

Auto DNS=0

Create a file called /etc/resolv.conf. Put a couple of name server entries that you know works. For example (/etc/resolv.conf):

nameserver 192.6.1.194
nameserver 198.6.100.194

That's it!

Regards, Chris G.

P.S. How can I disable the Link Quality Requests when using PPP with wvdial? I would look on the wvdial site, but their documentation did not even mention the "Auto DNS" configuration entry.

share the directory

Hi,

we have a lan setup of about 6-7 computers in our hostel. My problem is that i want to access files on other computers which have booted in windows, through linux.

I guess you found the button in win where you "share the directory" This is in windows what samba does for linux (actually samba implements the windows protokoll for file sharing).

we have got over the problem the other way round by configuring samba. can you help me on this.

looking forward to your reply

Search for linneighborhood using your favorite search engine.

linneighbourhood seems to be a frontend for all the smb tools to use windows shared in Linux. smbclient and smbmount are the most interesting ones to have a look at for first experiments.

K.-H.

Machine Check Exception!

Hi Answer Gang,

<Howdy!>

I'm a Linux Newbie, and I had some funny (maybe not so funny) problems with my system -

I'm running SuSE Linux 7.1 (Kernel 2.2), on an Intel Pentium-II(450 Mhz) box.

Hey -- you're running exactly the same distro and version as me. We also happen to be running the same kernel version. I think it's time we re-compiled our kernel using the latest sources!!

-- Thomas Adam

It used to hang all of a sudden, usually with a beep or two, and the keyboard, mouse and display would freeze.

I noticed the following message on my xconsole:

message from syslogd@shankha: shankha kernel: CPU0 Machine Check Exception 0000000000000004 shankha kernel: Bank 1: b200000000000115<0> kernel panic: CPU context corrupt

Do you happen to have Memory with parity? I've never seen a message like yours -- but this looks like a detected unrecoverable memory fault. (this bank 1 line gives me the hint).

grab memtest86 from somewhere and run it as long as it needs to throw the memory errors at you. Could be over night..... Check if the memory modules are sitting tight in their sockets and repeat. Exchange the memory modules and test again. If still errors occur throw it away and get a new one.

-- K.-H.

If you've got, say, four modules, do this: swap 1 and 2. If the error address doesn't change, then the problem is not in those; if it does, then swap 1 and 3. If the address doesn't change after that, the error is in #2; otherwise, it's in #1. I'm sure you can figure out the rest of the troubleshooting method from there.

-- Ben Okopnik

[TAG] two monitors

i have a 32 mb geforce 2 GTS running with a 21" monitor under mandrake 8.1 using xfree86 4.1.0 and latest nvidia drivers at 1600x1200 my question is can i run this resolution and put a 32mb tnt2 PCI graphics card in aswell to run at 800x600 i have run two montiors before on my windows box but both cards have to be at the same resolution, i am asking this as i have a spare graphics card and old 15" monitor laying around and want to put them to good use

I guess this release notes could give a hint:

http://www.xfree86.org/4.2.0/RELNOTES4.html#17

I myself run the NVdriver on a laptop -- but there use the nvidia TwinView option and it's one card with two screens. It rather convienient to define different resolutions and relations of the two screens (like the small one is s specific part of the large one for presentations where you can have additional shell windows nobody else is seeing on the beamer or you can tell it that the CRT is left (or right, above,...) the Laptop. Then the two screens act as one huge one. The same "restrictions" as in the XFree link apply: most Window managers just don't care about the screens and open the windows where ever they please -- which might be right across both screens.

The "normal" (i.e. not xinerma or Twinview) mode is to run two X-displays on the two screens. Then you can't just cross from one screen to the other dragging some window. You have to give it a "-display :0.0" or :0.1 as display name and the window will go there.

Since you've got the cards how about trying ? PCI ad AGP cards should be able to share or rearrange their resources so the can coexist.

K.-H.

winux?

after reading my favourite computer mag i became interested in one main topic of their ramblings

that was that there may be a operating system available soon called winux that can run linux and windows programs natively, i am unsure of who is trying to make this or wether it will go ahead, perhaps you know something about this new OS, because it seems quite interesting.

I think that's LindowsOS, see http://www.lindows.com

Neil Youngman

xfree86 4.2

On 10-Mar-02 Blandin de Chalain wrote: This is a multi-part message in MIME format.

would you please stop sending a hml-copy of everything? thanks.

For the record, yes we're a webzine, but no, your HTML does not help the web-editor's job in the slightest.

ive just found out about xfree86 4.2

me not. what's the special improvement to 4.1?

Well, hmm, maybe www.xfree96.org would have a good set of notes:

http://www.xfree86.org/4.2.0/RELNOTES2.html#2

Among other things the newer code is now less idiotic regarding the perfectly good S3 family cards I have around my place. However I'm not jumping from working X 3.3.6 for that alone. Lots of other new drivers to clue in on either older cards, or bleeding-edge-new cards. The mice drivers are sparter now. Gamers and other GL fans will be pleased to know Mesa got merged. Other cool things. PEX and XIE extensions are deprecated and SuperProbe was removed (waaaah, I liked being able to ask the darn thing what it thought it was finding, seperately of a startup attempt).

One of the beauties of free software, as well as the "everything is parts" UNIX-like philosophy, is that (drum roll please) you do not have to upgrade to the latest-and-greatest all the time just to make a few major apps work.

i am currently using version 4.01 on linux mandrake 8.1 and have = downloaded the nvidia drivers for my geforce 2gts i am unsure of what files i need to download as i cannot see a single = file, all i see is confusion as i am very new to linux,

the nvidia site is somewhat confusing there, I agree. But then it's only a very long list of binary distributions -- you want to get one of them only if it's matchings yous exactly.

Otherwise take the generic source tgz packet and compile yourself. The README contains the steps necessary to install them. It's long and goes through all of the various packages for all the distributions so you need to read only some part up front and then the specific part for the package you actually got.

Generally you will need the GLX-package and the kernel package.

can i install the nvidia drivers on xfree 4.01 and upgrade to xfree 4.2 = later.

no idea -- I'm running the 1.1514 nivida drivers right now and that does not require 4.2, so I didn't bother upgrading a running system.

Hmm, 4.2 says it released late January, so maybe if my more experienced eyes surf over to nVidia...

Hmm, "Drivers" at the top of the Nav, "Linux" last among the bullets, new driver release posted March 7. (wow, only a few days ago) Not that hard to find, at all.

The part more likely to be confusing to newbies is that the driver comes in two parts -- a component to be added to your X server, and a component to be added to your kernel source before building a fresh kernel. That means you'll want to have sources around for X (oh dear, building X isn't for novices) and for your kernel (make menuconfig is pretty easy to use).

Or, if you happen to use one of the two distros the nVidia people themselves use, you can get Red Hat or Mandrake packages... no SuSE, eh? that sucks. I seem to recall nVidia doesn't want other folks shipping their binaries? (clicking open that "Legal Info" link) hmm, standard corporate "this is ours not yours and you're licensed for one copy at a time" stuff. That would suggest that I'm right in this regard. Checking Debian, there's a package 'nvidia-glx-src' which builds it for you, but the version in testing is (no big surprise to me) not the one posted a few days ago. Which is ok since it still has xfree 4.1 in it too.

also how can i boot to console mode to install the nvidia drivers, or = can you just do it from an rpm installer in x.

nVidia notes that they have an NVchooser script you can use, and it will get you the right rpm.

You may be able to upgrade from X -- overwriting the former X drivers present. On reboot this could get you in trouble if your default is a graphical login.

I really would have X turned off while you update it. And I really would back it up, since if your X already works it's a running setup, and if the new stuff doesn't work so happily, you'd lose your GUI. Which is even worse than annoying if you use a GUI login prompt

Anyways the real reason it's important is that file handles for any old parts which are open, will not be re-opened to clue in. To be sure you did that you'd need to stop X anyway. Safer to know it all got tweaked at once, then turn it back on...

You could try typing (as root):

init 1

on the commandline of a shell which would bring you down to a text-login screen in single user mode. To test the news drivers you could try "startx" to get an X-screen back.

You might have to turn networking back on... single user mode strips a lot more than most people want. Me, I favor keeping a text mode runlevel around; that'd usually be telinit 3.

One of the few things that gives me a headache in Debian is that when you add new bits that darned thing tends to add them to ALL the runlevels.

If it's ok end it again and issue "init 3" or 5 (?) to get back to the graphical login.

traditionally it's been 5, but you really have to check your own system's init sequence to be sure. Before you start poking around in single user you can run the command 'runlevel' and it will tell you where you're at already. For me /sbin/runlevel generates N 3

meaning, I didn't have a "previous" runlevel, and I'm currently at runlevel 3 (consistent with me preferring text logins).

I'm not running mandrake so I can't give you too much specifics on the init levels they use or if there is something like startx.

K.-H.

I believe they still have a directory structure similar to RH in that regard. I haven't encountered distros without startx in a loooong time, but, if you use a GUI login that's not how you're normally launching it, but gdm or its cousins tend to use the same xinitrc under the hood.

-- Heather

Linux Journal's Weekly News Notes Tech Tips

You can use Python to extract stats from mail.

$ ./mail-predictor.py richard@ssc.com Mail/inbox Mail/richard
798 total messages from richard@ssc.com, 31 in this hour of the week.
Predicted activity level in the next hour: 6.526316

See attached mail-predictor.py.txt

Press Alt-F2, then enter ##make for the GNU Info page on make.

Shift-Insert pastes the last thing from Klipper into Konsole.

Use Control + to select files in Konqueror by shell pattern.

If fonts are coming out too small on Mozilla, and you want to block the browser from ever setting fonts below a certain size, just put

user_pref("font.minimum-size.x-western", 13);

in your user.js. (If you don't have a user.js, read "Customizing Mozilla": http://www.mozilla.org/unix/customizing.html.)

This option has changed from previous Mozilla versions; check out this bug report page: http://bugzilla.mozilla.org/show_bug.cgi?id=30910 for details.

This page edited and maintained by the Editors of Linux Gazette Copyright © 2002
Published in issue 77 of Linux Gazette April 2002

HTML script maintained by Heather Stern of Starshine Technical Services, http://www.starshine.org/

Contents:

¶: Greetings From Heather Stern

CRC errors on floppy disks

Can't See Boot Messages Even Though RedHat 7.2 Boots OK

The euro symbol

ntfs clobbered my ext3fs!!

Newbie seeking advice

Postfix name resolution fails, dig doesn't

Themes in Linux
a game of win-upsmanship

gaming in linux

linux questions

Greetings from Heather Stern

It's a party, by Jove! aargh, TrueReality strikes, he's caught in a trainwreq and can't host. nice that Amanda can be his backup, Pronto! The gals Rachel, Nadja, and Molly, help her jumpstart! Brunhilde, and edna handle the MUSIC, Thomas' brother gives out directions, and with my Best Effort I don't get lost.

everybuddy from the PostOffice was there, Cyrus, Althea, Ishmail, Fentun, Virge, Felix, Buffy, biff and their mutt. The old majordomo greeted us; the Maestro was in the rosegarden by the lilypond.

joe, kate, and ed were full of vim. DAVIS and JAMES brought out the snack tray: sawfish and bluefish with SAUCE, freshmeat with SPICE (ginseng, Oregano, SALT, and coriander, using a tenderizer), plus a Jellybean bowl. Jasper handed out CUPS of juice, c.o.l.a, WINE, Java, Espresso, plus all the virtual beer we could drink.

All is not Solid in the citadel though. Things got loco -- a Kaptain asked me into the ConferenceRoom so we could SpeakFreely. "The Comanche, Mohawk, Cherokee, are making a Martyr of the Apache, somebody's Wagon almost squished the Dillo, Wikki Tikki Tavi is holding the python and boa at bay, the nighthawk and our cat oneko are both chasing the cricket, the Anteater ate Langton's Ant and I'm afraid the BasiliX is about to turn them all into lawn ornaments. To top it off that pimp won't lose his smirc. Mama Mua, what a Maelstrom..."

"Don't Quake II much." I had a plan. Put a crafty SPiN on it and I Phorecast these FOLK would avert Doom and have a Grande time.

We should Definitely do this again next August.

CRC errors on floppy disks

From "David"

Answered By Dan Wilder, Heather Stern, John Karns

Thankyou for taking the time to read this. I am marked down as one of the university geeks, and it is coming around to the time to hand in essays/dissertations etc. Many people have put misplaced faith in the reliability of floppy disks. Is there any tool for linux, which will allow me to ask the floppy driver in the kernel to keep trying, so I can put together the statistically "best" hex dumps,or extract raw text from Word docs etc.

[Dan] 'Fraid I can't offer any way to recover the data once it's lost to bad sectors, tho no doubt some way is possible.

Instead I'd like to offer the format script I use for floppies before I'll trust 'em with my data. It culls out a lot of floppies, and I find that floppies which once passed, after sitting a few years on the shelf, will often no longer do so.

User who runs this must have write permission to /dev/fd0h1440. Requires mtools. Watch out, some distributions may obsolete fdformat in favor of superformat.

See attached goodfloppy.sh.txt

Today I resuced a 6 page essay 10hrs before it was due,

[Heather] The easiest way to do this sort of thing (I used to do it too) is

1. use dd to extract a raw image of floppy disks. This is sufficiently reliable that it's now the normal way I mount floppies on my laptop.

dd if=/dev/fd0 of=/usr/local/floppy/student-name-ddmmyy.144 bs=18k

In case you're curious 18k is the standard blocksize of a single track, so this is the "native" amount of bits the floppy read heads want to read anyway. It should be fastest and have the best chance of getting all the rescuable bits.

I already take a copy, as I am not the only geek with enough time, and I don't want to write anything back to a damaged floppy. Thanks for the advice with bs=18k I will use that next time.

[Heather] Yep, it's about 8 times faster with that set.

2. the rescue

1. See if Linux will mount the raw image - as it may be more reliable than a floppy whose cookie got slow (in other words a straight read is better than lots of little seeks)
2. if not, use 'strings' on the resulting file, noting that some of the ASCII bits will just be raw strings of letters from headers and things (e.g. "GIF89A")

Ugly but better than nothing during Finals Week.

Most disks that I have come across mount OK, but if all else fails, I have all night, a copy of Peter Nortons PC Programmers Bible (plenty on disk structure, FAT layout etc), and the promise of as much beer as I can drink from the hapless author.

[Heather] I got a full case of Henry Weinhardt's Root Beer once. The gal knows I don't normally drink alcohol. No wait, that wasn't in college, that was in the corporate world. I got some cool coffeecups... uh no, that was in the corporate world too. Nevermind

...but the 200 words held on the bad sectors were well and truly gone.

[Heather] Sorry. Once there's scratch marks there, they lose.

This is not so good, what I was really after is someway to attempt to make best guesses for what is in those bad-sectors. I know that it sounds difficult, but I am looking for something between Scandisk for windows, and professionals in a clean-room!

[Heather] We have dosfsck, of completely unknown reliability, but you're welcome to try it too. What the heck.

Short of trying the floppy again in a floppy bay with different alignment, basically you either got the bits, or you didn't. And indeed, you could try that (though it submits the poor dented floppy to N more visits by drive gear) and see if the md5sums of any of the dd images are different. If so, scour the tweaked ones for anymore bits you can rescue also. Don't hold your breath, but you'll have earned the extra brewskies if it works.

Clean-room efforts are basically able to micro-position the heads in the hopes of seeing the last two to five major writes. Ontrack does such recovery, but I dunno if they do floppies at all. I suspect not.

Is there anything better than dd conv=noerror, that will allow me to access these dodgey disks from linux. I am kind of looking for something like Spinrite by Steve Gibson, but I would like to have it for linux, and for free.

[Heather] spinrite worked on IDE drives, not floppies.

If you want a hex editor in the spirit of Norton Disk Editor, try lde, but frankly, I'd use 'hexedit' (a curses-terminal program) on a dd image of the floppy before I'd consider that ... to reduce the amount of usage tried on an already poor-condition floppy.

Oh yeah, and much as ZIP and LS-120 bays are less popular, their cartridges are much more reliable than standard floppies, and CD-RW even more so (but sadly CD-RW cannot be written to directly, just burned as a complete image -- and DVD-RAM drives are still not in the normal-consumer price range, plus they're rare even in the Silicon Valley).

Forget DVD-RAM / CD-RW. Most people use floppies to move work between computer labs with internet, and our rooms without. Nobody in college has administritave access to the networked PC's, and the amount of people who simply use a floppy to avoid copying files around is scary. We have just got new ZIP-250's, so things should look up for next term!

[Heather] Well, definitely looking up there!

Oh yeah, remind people not to leave their floppies (or cartridges) lying around in the noonday sun on the car shelf, or other places where they would get toasty and you wouldn't put VHS tapes. It's basically the same type of media with the same type of susceptibility to heat damage.

[John] I usually keep floppies in the box they came in or in a small plastic bag. If you examine one, you'll see that they have an open slot at the top edge where the sliding metal access door is. When left out in the open air, floating particles enter and adhere to the surface of the plastic disk inside.

Zip disks don't seem to have such a comparatively large opening in the housing as floppies, which may a reason they fare better. But one is very well advised to keep all magnetic media, including tapes, in a protective case or other dust barrier. I've noticed that plastic materials seem to act like magnets for carbon dust, which when smudged leaves a grease spot on the plastic material.

[Heather] I am reminded of a time that we posted somebody's ruined floppy to the student-center wall... pried loose of its plastic envelope so the round disc was revealed, dent and all. Caption: "Don't do this to your floppy". I forget exactly what did it. The crease wasn't much - maybe someone sat on it, I dunno. But it was definitely dead.

I don't know if your policies are about guest-level access only or you create actual accounts for people there. If the latter then some sort of share server (samba or perhaps one of those file-appliance boxes that have gotten so popular) which looks like the same drive letter on all networked boxes, would get people to use that instead. I like H: for "home" but your tastes may vary. Combined with the permissions-by-login behavior samba can provide it's not too bad. You might not want to make it automatic or perhaps people will abandon logged in machines and mess up each other's space. And not everyone would use it, perhaps they want to take some work back to the dorm with them. They might even get them out of sync. (I think the MSwin buzzword for doing it the right way is "My Briefcase" but don't quote me, I could be wrong these days. Here in linux we use rsync, and have to be careful about the commands we give it, too.) In other words it has its own headaches... but it's not as unreliable at the bits level as floppies are.

I think that's about as much as Linux can really do for throwing software against what is basically a hardware and a clue-ware problem, but there ya go. Best of luck in the efforts!

Thanks in advance

David

P.S. If you publish my e-mail can you obscure it somehow. My uni acct is so far spam-free and I would like to keep it that way.

[Heather] Yes, we can anonymize you. If this stays short enough for Tips we'll put "anonymous" instead of your email, and if enough of the Gang chime in it may be a TAG thread, where emails are not published at all unless directly related to the solution (e.g. project maintainers).

Can't See Boot Messages Even Though RedHat 7.2 Boots OK

From Bill Rust

Answered By Thomas Adam, Heather Stern

Hi,

I'm at a bit of a loss. When I install RedHat Linux 7.2, I get the Grub menu, and after I select Linux, the screen goes blank.

[Thomas] This happens on my "oh so wonderful" laptop occasionally. I know this may seem strange, but does the blank screen go, if you press any key on your keyboard????

I can see the hard disk accessing, and after a couple of minutes X starts, and life is good.

[Thomas] That really depends as to whether or not you like using X-Window (X11). Personally, I am much more comfortable at the console.

When I check my dmesg and /var/log messages file, I see no error messages on the boot. I also noticed that when I boot for the install and to boot in rescue mode, I not only get messages, I get the picture of Tux in the upper left corner of the display.

[Thomas] BINGO!! The fact that Tux appears in the upper left hand corner of your screen immediately suggests that you are using Framebuffers for your display. What this does, is it forces the console to display at a certain resolution, such as 800x600. It is particularly suited to laptop users. But why you should have FB when loading the "rescue" mode is strange......

I've searched high and low in Google (web and groups), and your archives and can't seem to find an answer. Any help would be appreciated.

Hardware:


Athlon 1.33GHz (clocked at 1.33, at least for now)
ATA 100 UDMA Promise (motherboard) IDE
IBM 7200 RMP 40GB HD
Geforce 2 TI/AGP w/64DDR
SB Live value
52x CDROM
12/10/32A Plextor CDRW

I am dual booting with Win98SE (for games)

Things I've tried:

• Booting with LILO instead
• Setting vga=ask in lilo.conf
• Removing 'message=/boot/message' from lilo.conf
• Installing the Geforce drivers from their website (they worked great by the way, and I was able to run GL stuff very fast indeed!)
  

[Thomas] Since you have already changed your lilo.conf file to:

vga=ask,

then perhaps we can rule out the this cannot be a FB (FrameBuffer) problem???

[Heather] Probably the modelines it is calculating for "text mode" are not quite in your monitor's range. The nice thing is since X works you can use xvidtune or even capture the console messages to find out which modeline it is using, and there is some utility out there which can convert X modelines to framebuffer values. Unfortunately I don't recall what it is, But fbset would be the tool you'd use with the resulting knowledge of a good horizontal sync, vertical refresh, and dotclocks rate.

Telling LILO to use vga=ask is only half of the troubleshooting -- you also need to know what to answer, because the nice graphical-text modes will not be listed there. Here's the table from the Linux sources /Documentation/fb/vesafb.txt file:

    | 640x480  800x600  1024x768 1280x1024
----+-------------------------------------
256 |  0x301    0x303    0x305    0x307
32k |  0x310    0x313    0x316    0x319
64k |  0x311    0x314    0x317    0x31A
16M |  0x312    0x315    0x318    0x31B

But, oh no, it warns that LILO cannot handle hexadecimal, you have to change them to decimal, 771 for instance.

Try any of these until one of them makes your system happy, then tell LILO to use it all the time instead of asking any more.

[Thomas] (You did remember to run:

lilo

after you updated the lilo.conf file ??? )

Other than trying my suggestions already mentioned, I don't know what else I can do.

Perhaps you could send us a copy of the command:

dmesg &> ~/dmesg.txt

output???

Kind Regards,

Thomas Adam

P.S. I like the structure of this e-mail. It clearly states the problem, and what the querent has tried to do in order to solve it -- well done!!!

Ben's article is working.......

Thanks for the quick response!

[Thomas] All part of the service!

OK, I tried the keyboard thing after the screen went blank; no such luck, same behavior

[Thomas] Oh well. It was always a "shot in the dark" (do excuse the pun!)

I tried setting my initdefault to 3 instead of 5 in the /etc/inittab file. It still went blank immediately after the grub menu goes away,

[Heather] Oh dear, I don't know how to tell it to use other VGA modes in grub. With any luck it's just an extra option that the kernel itself acceopts,

but interestingly enough, I never got a prompt after what I can only presume was the end of the boot process.

[Thomas] Thats because you don't usually get "a prompt" (well, you do, but....). By prompt, I assume that you mean a login prompt?? What happens when you change your defaulr inittab to 5 is that your login prompt does appear in text, but is immediately switched to tty7 where a graphical one takes its place.

I know this may seem strange, but you should "listen" to your monitor as it boots up into init 5. If you hear a series of clicks then it is booting into a graphical display ok.

Since I'm working blind here, I can assume one of two things

[Thomas] ...

1) my console is not functioning

[Thomas] No....its functioning ok. You said it yourself, that you can get a prompt if you do a CTRL-ALT-FX key sequence.

or 2) the system is hung. I suspect the latter, because when I try to bring up another terminal (CTRL-ALT F2, F3, etc), I still get nothing - by the way, CTRL-ALT F2 does work when I boot level 5. I used the CD in rescue mode to reset my inittab back to 5, and here I am up and running again (still have the blank screen tho).

[Thomas] You know, I have had this situation before. In some displays, there is a problem of getting the text to display itself when at the console.

What you could try, is the following:

[ ** I do not know how the init structure (i.e.
location of files is
organised under RedHat. But, if it is anything like
SuSE, then the init
files should be in "/etc/init.d" -- as per the LSB
standard ** ]

You should have on your system, a file called:

boot.local

into this file, add the following command:

setfont &

That might, un-blank your screen, it works on my laptop, and might just solve your problem.

I forgot to mention that I tried the 'nofb' argument after reading the bootprompt HOWTO. I'm not ready to rule out the frame buffer, however.

Maybe the answer would be to try to get it to work.

Any pointers as to where I could find a HOWTO??

[Thomas] Aye....you could have a peek at the following website:

http://www.linuxdocs.org

With regards to the lilo question. Yes, I did run lilo after the changes. The reason I am referring to the Grub screen now is because I eventually had a boot problem.

[Thomas] What kind of boot problem?? Lilo has been the de-facto boot loader for Linux, for years, and is adept and handling most things in my opinion. And it now offers nice colourful menus, which it did not before.

Since, I couldn't see the screen, I couldn't see an error message. I was then able to use the rescue mode on the CDROM, but I couldn't find anything in the /var/log/messages file. I also did an 'ls -lrt' in the log directory to see if there were any newly updated files from the same day, but didn't see anything. I eventually gave up and reinstalled Linux.

[Thomas] Hum....this is a very interesting problem Bill.

I have attached the dmesg text. Thanks for the tips; I hope we can get this mystery solved!

[Thomas] I'm trying

I looked over your dmesg output...nothing out of the ordinary there.

Keep at it. I hope I have been of some help. Do let me know if my suggestion succumb or not.

Kind Regards,

Thomas Adam

[Heather] Unfortunately that dmesg output was lost from the threads visible to me. However, I post this note here, with my additional comments about selecting framebuffer modes, and in the hopes that someone amongst our readers may be able to shed some light on his monitor's darkness.

The euro symbol

From Mark McGrath

Answered By Jay R Ashworth, Mike "Iron" Orr, Yann Vernier, Ben Okopnik, Andreas Daab

Here's an interesting question that I thought you might take a look at. IT applies more to the Europeans among us but then maybe the wider community might benefit if it were broadened to the wider question of dealing with different fonts!

How is it possible to view the euro symbol on programs running on linux machines, programs like netscape, emacs, mutt, etc., etc.,

Thanks in advance.

Slán,

Mark.

[Jay] I quoted all of that for a reason.

This is a good one, and one that's cropping up on several of the mail lists in which I participate, as well. It's a multi-faceted problem.

Using non-ASCII characters (I was going to say "on a PC", but that's sort of obvious) requires several things:

• A way to type them in.
• A way to ensure that the OS you're using knows which character set they're in. (A character set is a mapping of bytes to glpyhs, a glyph being a picture of a character in a font. You can have many fonts in the same character set.)
• The program has to be equipped to handle incoming characters in arbitrary character sets, and either to retrieve the mapping information from the OS, or be told it itself.
• If the program interacts with other programs, there has to be a standardized way of tagging which information is in which character sets.
  and finally
  
• A way to get them back out on the screen so you can read them.
  

Each of these is handled, in Linux, by different things, and you need to make sure that all the pieces are in place. Frankly, I wouldn't be surprised at all to see an amendement to X3.64, the ASCII standard (which I think is also ISO 10646), to include the Euro character.

Actually, I'm surprised it's not there already.

[Iron] There aren't any empty slots in ASCII. You'd have to replace something like the backslash or the pipe symbol, and that would wreak havoc on situations that don't expect these glyphs to change, like ASCII art, shell scripts and Windows pathnames.

[Jay] Well, no, I think you could find some other character to replace. I should clarify that I really don't mean USASCII (the 7 bit character set), what I really mean is "the most common 8-bit extended version of ASCII" -- though admittedly I don't know what that is. ISO-8859-0?

[Yann] -1, for western europe. -2 is eastern europe. Euro variants are -15 and -16 respectively, I think. The replaced character is €, which is an ancient sun symbol that also means "currency". It has the high bit set. Swedish people got lucky in that some odd person decided to put that character on our keyboards long ago - it's at Shift+4, with $ at AltGr+4. However, this also means that our keys are now marked with both "sol" (sun in swedish) and "Euro" (AltGr+E), but in different positions, and either one may or may not work.

[Iron] Although I think character 35 (# or number sign) shows up as L (pound sterling) on British screens and other currency symbols in other places, no?

[Jay] Yeah, it tends to...

An answer to this question of the Euro has, probably not all that s