Linuxers October 2001

linuxers@mm.ilug-bom.org.in

73 participants
110 discussions

by nici bhatt

hi well no probs we can carry on but we have to decide which is best possible way and easy way for this. aprat from how-to's and faq we need to have day-to-day problem which are faced by our mailing list user and there solution which they have got from this mailing list this will help our mailing list to improve it's purpose aprat from this we can have list of applcation which are devloped and late braking news so wht do you think? is this ok. Nici >From: "Nagarjuna G." <nagarjun(a)hbcse.tifr.res.in> >Reply-To: linuxers(a)mm.ilug-bom.org.in >To: <linuxers(a)mm.ilug-bom.org.in> >Subject: Re: [ILUG-BOM] db.ilug-bom.org.in >Date: Tue, 23 Oct 2001 16:39:02 +0530 (IST) > >On Mon, 22 Oct 2001, Sameer D. Sahasrabuddhe wrote: > >->--- "Nagarjuna G." <nagarjun(a)hbcse.tifr.res.in> wrote: >->> I have created and started uploading useful resources for GNU/Linux. >->> The URL is: http://db.ilug-bom.org.in/ >->> >->> I also need volunteers to maintain this site. Also give me >->> suggestions regarding the use of this area. If you have any material >->> that you wish to upload, let me know. >-> >->I volunteer! >-> >->What I really ache for is an Indian mirror for Debian, esp unstable. > >Very good! I got four volunteers. Sameer and Jaju are both in IIT, >so coordiation will be easy. Navin and Nici Bhatt have also >volunteered. I suggest that Sameer and Jaju take care of downloading >the stuff, using preferably rsync or wget or some such mirroring >software, and Navin and Nici Bhatt take care of providing a web >interphase for the resources. Is this OK? > >I have already kept potato R3, three disks in the area. i have not >yet started uploading woody. I will issue the command today, and may >be in few days the stuff should be there. > >Apart from LDP, what other things should we have here. > >Nagarjuna > > >_______________________________________________ > >http://mm.ilug-bom.org.in/mailman/listinfo/linuxers > _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp

21 years, 5 months

[tech] [info] Linux module loader

by Philip S Tellis

<preamble> This lecture was first given at the MCA day at VJTI, and then repeated along with a demonstration of the proc filesystem at the Linux workshop at VJTI Note: This has to be read along with the following files: /usr/src/linux/Documentation/ kmod.txt modules.txt man modprobe man insmod man lsmod man kerneld man ksyms I'd also suggest reading Linux Device Drivers, 2nd Edition http://www.xml.com/ldd/chapter/book/index.html </preamble> Monolithic kernels and Microkernels - Linux was based on Minix - Minix has a microkernel, but it doesn't do it very well - Linux has a monolithic kernel - Linux was written because Linus wanted to learn how his 386 works What's the difference? Monolithic - the whole kernel is a single a.out file - the whole kernel is loaded into memory - all communication within the kernel is through in process data structures Microkernel - most of the OS is outside the kernel - services communicate via message passing - the kernel implements this message passing - the kernel also implements interrupt handling, low-level process management, and possibly IO. Linux is obsolete - AST OS Researchers have generally settled on the fact that microkernels are better. This was decided back in the mid to late eighties. So, is linux obsolete? Modules - No one really knows who came up with the idea - It was first implemented in the 0.99 kernel series - insmod, rmmod, modprobe and kerneld How does it work? - All modules are not linked into the kernel at build time - Slots that have been marked as modules are left empty - These slots are actually linked to an internal function called request_module() What happens if a module is needed? The kerneld way: - The kernel notices that a feature is requested that is not resident in the kernel. - The kernel sends a message to kerneld, with a symbolic description of the requested feature. - The kerneld daemon asks e.g. modprobe to load a module that fits this symbolic description. - modprobe looks into its internal "alias" translation table to see if there is a match. This table can be reconfigured and expanded by having "alias" lines in "/etc/modules.conf". - insmod is then asked to insert the module(s) that modprobe has decided that the kernel needs. Every module will be configured according to the "options" lines in "/etc/modules.conf". - modprobe exits and kerneld tells the kernel that the request succeeded (or failed...) - The kernel uses the freshly installed feature just as if it had been configured into the kernel as a "resident" part. modprobe, insmod, kerneld? What are these things? - kerneld is just another daemon. - runs in the background, communicates with the kernel through Sys V IPC - loads modules when required, unloads them after (usually) 1 minute of no use - insmod links a loadable module into a running kernel - it must resolve symbols from the kernel's exported symbol table - modprobe is a wrapper for insmod - it checks modules for dependencies listed in modules.dep - it checks its alias file - it loads all matching modules, and their support modules But that's not the way it's done anymore - As of 2.1.90-pre1, kerneld has been replaced by kmod - kmod is a kernel thread, not a user space daemon - kmod doesn't do everything that kerneld did B-b-but why? - in the end, modprobe is called, so why have an extra user space process? - kerneld used Sys V IPC to communicate with kernel - doesn't use unix domain sockets for logging - code size of ipc/msg.c decreased by 40% So what does kmod do? - has a replacement for request_module() - runs as a separate kernel thread called kmod - when a module is requested, kmod wakes up and execve()s modprobe And what must I do? - kmod needs to know where it can find modprobe - echo "/sbin/modprobe" > /proc/sys/kernel/modprobe - or use sysctl - of course, you could put this in your startup scripts and forget about it - you also need to manually unload unused modules... but that's what cron is for So.... - the modular kernel doesn't use up as much memory as traditional monolithic kernels - kernel modules can be updated without recompiling the kernel - your kernel can be really small - Linux is not obsolte, on the contrary, we can all look forward to version 3.0 -- Scully: I'm seeing a whole new side of you, Mulder. MulderEddie: Is that a good thing? Scully: I like it. "The X-Files: Small Potatoes" Visit my webpage at http://www.ncst.ernet.in/~philip/ Read my writings at http://www.ncst.ernet.in/~philip/writings/ MSN philiptellis Yahoo! philiptellis AIM philiptellis ICQ 129711328

21 years, 5 months

Re: [ILUG-BOM] db.ilug-bom.org.in: will it be used?

by Sameer D. Sahasrabuddhe

Philip wrote: >To break my stand, I vote in favour of a fork. Me too, for lack of a better option ... Two things I would like to point out: As Jaju had remarked to me, been a long time since somebody actually started a good thread on something that they were using/recently discovered that made me sit up and hit the docs. Like Philip pointed out in his mail, people answering newbie questions should try their best of making them read the docs rather than just answering questions. SameerDS. _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com

21 years, 5 months

[OT]

by Sandeep Periwal

Hey, Does anyone know of sites which has some info about.. ++>Acceptace of Linux by big time corporates ++>OS level migration by cos ++>the future of linux.. in years to come by some publicly known org. I am preparing a small paper on Linux ... "Linux :Past, Present & Future." Any & all Inputs, Pointers etc are warmly welcome. --Sandeep __________________________________________________ Do You Yahoo!? Make a great connection at Yahoo! Personals. http://personals.yahoo.com

21 years, 5 months

[OT]

by Sandeep Periwal

21 years, 5 months

Re: pppd error no. 17

by Parul Mathur

On Fri, 19 Oct 2001 Kinjal Sonpal wrote: >Btw, for allowing all the users on my home PC system, chmoded >/dev/modem to 777. Is this okay or is there some better >>workaround? I did this becoz I read somewhere in our mail >archives that one shud not dial-up as root for the sake of >security reasons. PCQ has the following advice: (Do all this as root.) Step 1: Add a group called 'dialout'. Step 2: Add the required user accounts to this group. Step 3: Type the following commands: $ chown root.dialout /usr/sbin/kppp $ chmod 4750 /usr/sbin/kppp Step 4: Create a file /etc/kppp.allow and type the user names of users who are in the dialout group, each user name on a separate line. The users should run /usr/sbin/kppp rather than /usr/bin/kppp. (This is assuming you have a typical Red Hat installation in which /usr/bin/kppp is a symbolic link to /usr/bin/consolehelper and the actual binary is /usr/sbin/kppp.)

21 years, 5 months

Pop3

by shahazad＠linuxplanet.nu

hi, i wanted to know that where could i get a service provider wherein i would be able to check my POP3 & reply through the same mail id via a browser. i know about mail2web.com but mail2web ads a advertising line below .. also through that i cant configure to put my name on the outgoing mail instead my name & mail id is the same at mail2web.com so plz let me know about other service providers such as that wherein it would allow me to configure my Pop3 in the above way. cheers~ </shahazad> -- Get your firstname@lastname email for FREE at http://Nameplanet.com/?su

21 years, 5 months

Test Message

by Nagarjuna G.

Test Message, please ignore Nagarjuna

21 years, 5 months

Simulating Socket errors

by Shahed A Moolji

Hi, Are there any linux commands to close a socket conenction between 2 processes ? eg, I can use the ipcsrm command to clear shared memory etc. Is there anything like that for sockets. Here is What I want to do :- I have a TCP Server and a Client. I want to simulate a "Connection reset by peer condition" on the client side. I do not have access to the Server Software. In my client software, I am doing a block wait on a select(). Under certain circumstances, due to network problems, the connection is reset, but the select() does not return any errors. i.e It is still blocked. Is there any way I can simulate this ? I have tried using the shutdown() api call from within my program to close socket communication, but that causes the select to return. I also thought of pulling the network cable on the client machine, but I dont think that will simulate the error that I want. Thanks Shahed.

21 years, 5 months

Re: bd.ilug-bom.. will it be used?

by Anand

Hello Philip, What you say is true, People do not seem to be taking the time to research the site, but just pop up questions hoping that their invaluable time is saved by others spending their invaluable time in answering the original mail. I believe it is the " You have to help me " Syndrome. People believe that the problem they have is unique in some way and that there are others who are there to help them, rather are obliged to help them. They may be ready to pay for it. A small price may be nothing. We can put up a compilation of the different problems that were solved by LUG mails and a set of CD's could be made available for sale at writing price plus a small margin for people who put up all the effort. We can also incorporate useful tips and hints from advanced users. A part of the profits can also be used to finance future LUG activities. In the future, if the problems asked are repetitive, then only reference to the CD can be made. Anand -- ------------------------------------------------------------------------ Visit www.smbd.org <http://www.smbd.org> for Free Tutorials, Source Codes and Other stuff. ------------------------------------------------------------------------

21 years, 5 months

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Linuxers October 2001