December 2003 - Legacy - lists.gtalug.org

C programming question
by wildberger-iRg7kjdsKiH3fQ9qLvQP4Q＠public.gmane.org 23 Dec '03

23 Dec '03

On December 23, 2003 06:45 pm, Matthew Rice wrote: > And this is better than: > > od -j 68 -N 2 -t x2 /dev/mem > > because??? ;) You don't get an argument from me on this. :-) I actually used this to verify my program. It is short, but not as much educational as writing a C- program. > > > short x; > > ssize_t size = read( fd, &x, 4 ); > > Shorts aren't 4 bytes. Perhaps you should change the '4' to: > > sizeof(short) > or sizeof(x) It does not chane the result. I used the 'short' to get away from a printout with four bytes (high order first, followed by low order) which was confusing and not what was asked. > > or even better, use mmap(2). I will experiment with this as a next step in my education. > > Or even way better, read a book: Better, but a lot more cumbersome. In addition, it is very hard to find what one needs in specific cases. Just read some of the responses to my original question and you will see that my problem was not of a nature to bring forward answers from people that have read a lot of the pertinent books. > > Title: Understanding the Linux Kernel > ISBN: 0-596-00213-0 > > It'll be much less painful. Thans for your response, John -- The Toronto Linux Users Group. Meetings: http://tlug.ss.org TLUG requests: Linux topics, No HTML, wrap text below 80 columns How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml

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C programming question
by matt-s/rLXaiAEBtBDgjK7y7TUQ＠public.gmane.org 23 Dec '03

23 Dec '03

John Wildberger <wildberger-iRg7kjdsKiH3fQ9qLvQP4Q at public.gmane.org> writes: > changes to the effect that I can specify on the command line the memory > location I want to look at. > For instance to look at memory location 68 you have to type: > ./mem 68 > The result is: > 2 bytes at offset 68 are: f84d And this is better than: od -j 68 -N 2 -t x2 /dev/mem because??? ;) > short x; > ssize_t size = read( fd, &x, 4 ); Shorts aren't 4 bytes. Perhaps you should change the '4' to: sizeof(short) or sizeof(x) or even better, use mmap(2). Or even way better, read a book: Title: Understanding the Linux Kernel ISBN: 0-596-00213-0 It'll be much less painful. HTH, -- matthew rice <matt-s/rLXaiAEBtBDgjK7y7TUQ at public.gmane.org> starnix inc. phone: 905-771-0017 x242 thornhill, ontario, canada http://www.starnix.com professional linux services & products -- The Toronto Linux Users Group. Meetings: http://tlug.ss.org TLUG requests: Linux topics, No HTML, wrap text below 80 columns How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml

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C programming question
by wildberger-iRg7kjdsKiH3fQ9qLvQP4Q＠public.gmane.org 23 Dec '03

23 Dec '03

On December 22, 2003 10:19 pm, Greg Franks wrote: > With all due respect, are you really sure that you know what you are > doing and or what you want? Well, most of the time I don't know what I am doing. However, for guys that are even more challenged I have converted your program to c++ and made a few changes to the effect that I can specify on the command line the memory location I want to look at. For instance to look at memory location 68 you have to type: ./mem 68 The result is: 2 bytes at offset 68 are: f84d Here is my modified version: /* mem.cpp * Original program 'mem.c' by Greg Franks Dec 22 2003 * modified, converted to C++ and commented by J.Wildberger * execute with: ./mem + arg (memloc in decimal number) * compile with: c++ -o mem mem.cpp */ #include <iostream> #include <fcntl.h> //required for O_RDONLY #include <unistd.h> //required for lseek #include <iomanip> //required for setbase using namespace std; int main(int argc, char *argv[]) { if (argc != 2) { cout <<argc<<endl; cout <<"Specify memory offset from zero"<<endl; exit (1); } int n=atoi(argv[1]); int fd = open( "/dev/mem", O_RDONLY ); //open for read only if ( fd < 0 ) { perror( "Cannot open /dev/mem: " ); exit( 1 ); } else { off_t offset = lseek( fd, n, SEEK_SET ); if ( offset == (off_t)-1 ) { perror( "Seek: " ); exit( 1 ); } else { short x; ssize_t size = read( fd, &x, 4 ); if ( size == -1 ) { perror( "Read: " ); exit( 1 ); } cout << "2 bytes at offset " << n << " are: "<< setbase(16)<< x << endl; } } exit ( 0 ); } -- The Toronto Linux Users Group. Meetings: http://tlug.ss.org TLUG requests: Linux topics, No HTML, wrap text below 80 columns How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml

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Required DRAM 168 pin FPM 5V
by teddymills-VFlxZYho3OA＠public.gmane.org 23 Dec '03

23 Dec '03

Any one have this type of DRAM? I would post this to NNTP, but I dont have access to NNTP. Actually im kinda glad my ISP is not using bandwidth for NNTP. As I understand, USENET servers can be really bandwidth intensive. --------------------------------------------------------------- teddy mills http://www.vger.ca Family Guys Quagmire "allllllllllllllllllllllllllllllll right" Capt Tenneal "LETS GO!" -- The Toronto Linux Users Group. Meetings: http://tlug.ss.org TLUG requests: Linux topics, No HTML, wrap text below 80 columns How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml

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[xawtv and webcam looping]
by taavi-LbuTpDkqzNzXI80/IeQp7B2eb7JE58TQ＠public.gmane.org 22 Dec '03

22 Dec '03

On Mon, Dec 22, 2003 at 10:58:45PM -0500, Justin Zygmont wrote: > what I don't like about this is that if someone gained access to your > computer, they could gain access to the other computer without even having > to supply a password. That'd be the point of the ssh-agent and/or keychain; to prevent trivial unauthorized use. Naturally if an authorized program gets compromised, you're screwed. > > Use ssh-agent or keychain. More info at: > > http://www-106.ibm.com/developerworks/linux/library/l-keyc2/?open&l=252,t=g… Do check the link. Daniel writes good stuff. -- taa People in the 1950s, were increasingly told by carefully designed mass media formulas who they were, what they should be, and how they could succeed. These formulas were not geared to the development of a sensitive human being. --R. Altschuler and N. Regush /*eof*/ -- The Toronto Linux Users Group. Meetings: http://tlug.ss.org TLUG requests: Linux topics, No HTML, wrap text below 80 columns How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml

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[xawtv and webcam looping]
by jzygmont-tEQKYFGiemxAYG7eUwYNkWD2FQJk+8+b＠public.gmane.org 22 Dec '03

22 Dec '03

what I don't like about this is that if someone gained access to your computer, they could gain access to the other computer without even having to supply a password. On Mon, 22 Dec 2003, Ladislav Svatos wrote: > > > 2) SSH transfer option could not be performed without manually entering a > > password. I even set up all the authorized keys and it still prompts me for > > a passphrase - I suspect an 'expect' syntax error, but I at least feel more > > secure... > > Use ssh-agent or keychain. More info at: > http://www-106.ibm.com/developerworks/linux/library/l-keyc2/?open&l=252,t=g… > > > > Lada > -- > The Toronto Linux Users Group. Meetings: http://tlug.ss.org > TLUG requests: Linux topics, No HTML, wrap text below 80 columns > How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml > -- The Toronto Linux Users Group. Meetings: http://tlug.ss.org TLUG requests: Linux topics, No HTML, wrap text below 80 columns How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml

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C programming question
by rgfranks-cmaem7PIVQT44Nm34jS7GywD8/FfD2ys＠public.gmane.org 22 Dec '03

22 Dec '03

>>>>> "John" == John Wildberger <wildberger-iRg7kjdsKiH3fQ9qLvQP4Q at public.gmane.org> writes: John> Could I ask you to expand on your two words a little bit by John> using the info in the man page in a concrete way, e.g show John> me how to access physical memory at address 0x200 to 0x205. John> Thanks, John With all due respect, are you really sure that you know what you are doing and or what you want? You must be root to run this. *** Writing to /dev/mem will probably crash and or corrupt your system. *** You can use mmap too. /* mem.c -- Greg Franks Mon Dec 22 2003 * * $Log$ */ #ifndef lint static char *rcsid = "$Header$"; #endif #include <stdio.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <unistd.h> main() { int fd = open( "/dev/mem", O_RDONLY ); if ( fd < 0 ) { perror( "Cannot open /dev/mem: " ); exit( 1 ); } else { off_t offset = lseek( fd, 0x10, SEEK_SET ); if ( offset == (off_t)-1 ) { perror( "Seek: " ); exit( 1 ); } else { long x; ssize_t size = read( fd, &x, 4 ); if ( size == -1 ) { perror( "Read: " ); exit( 1 ); } fprintf( stderr, "Offset 10 is %x\n", x ); } } exit ( 0 ); } % sudo ./a.out Offset 10 is f000ef6f For the lazy, try: % sudo od -x -N 100 /dev/mem 0000000 0001 0000 ef6f f000 e2c3 f000 ef6f f000 0000020 ef6f f000 ff54 f000 8008 f000 ef6f f000 0000040 fea5 f000 e987 f000 ef6f f000 ef6f f000 0000060 ef6f f000 ef6f f000 ef57 f000 ef6f f000 0000100 10fa c000 f84d f000 f841 f000 aa9c f000 0000120 e739 f000 f859 f000 e82e f000 efd2 f000 0000140 e7a4 f000 -- __@ Greg Franks <| _~@ __O _`\<,_ Ottawa, Ontario, Canada |O\ -^\<;^\<, (*)/ (*) (*)--(*)%---/(*) "Where do you want to go today?" Outside. -- The Toronto Linux Users Group. Meetings: http://tlug.ss.org TLUG requests: Linux topics, No HTML, wrap text below 80 columns How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml

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Waaaay offtopic
by james.knott-bJEeYj9oJeDQT0dZR+AlfA＠public.gmane.org 22 Dec '03

22 Dec '03

Sergey Kuznetsov wrote: >>Also, the combination of Vitamin C and Echinacea supplements work very >>well to guard against the flu and common cold. Again, it's just >>personal experience and that of others. >> > > > This combination works for me. I am using the combination of Vitamin C + > Echinacea + Zinc + Golden Root + Ginseng mixed together. > Once again, how do you know it works??? How do you know you would have had a cold or flu, if you hadn't taken that stuff? -- The Toronto Linux Users Group. Meetings: http://tlug.ss.org TLUG requests: Linux topics, No HTML, wrap text below 80 columns How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml

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Incredible frustration at Grub/linux!
by jzygmont-tEQKYFGiemxAYG7eUwYNkWD2FQJk+8+b＠public.gmane.org 22 Dec '03

22 Dec '03

I do this all the time, just the other day in fact, with the drive you gave me. I image drive to drive andthen grub just needs to get reinstalled, then it should work. type: grub then at the grub prompt type: root (hd0,0) find /boot/grub/stage1 setup (hd0) quit of course substituting 0,0 for your correct drive/partition. On Mon, 22 Dec 2003, Madison Kelly wrote: > Hi all, > > I have been -trying- to setup a server with a '/' filesystem of > 'reiserfs' for later use under LVM and some HA software but I have been > absolutely unable to get past the starting gate and on top of feeling > flat out stupid I am also getting terribly frustrated. > > I want to do one, little simple thing - make a backup of '/' to > another drive/partition and then reboot using it. It seems that > absolutely no matter what I do, what file I edit or what I try to force > the system (Fedora Core 1) INSISTS on using the original '/' (in this > case '/dev/sda1'). I don't what the heck I am doing wrong but I am about > to blow a gasket. I have never been so fsck'ing mad at Linux before. Why > is it so damn hard to mount a different '/' partition?! > > Anyway, I am using Grub because it is the only boot loader available > on Fedora. I have tried reading the docs and am doing so again after > sending this to see if I missed something simple... > > Bah, if nothing else this is a rant that may help me cool down enough > to find my problem. Sorry for the noise. > > Madison > > -- > The Toronto Linux Users Group. Meetings: http://tlug.ss.org > TLUG requests: Linux topics, No HTML, wrap text below 80 columns > How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml > -- The Toronto Linux Users Group. Meetings: http://tlug.ss.org TLUG requests: Linux topics, No HTML, wrap text below 80 columns How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml

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Incredible frustration at Grub/linux!
by opengeometry-FFYn/CNdgSA＠public.gmane.org 22 Dec '03

22 Dec '03

On Mon, Dec 22, 2003 at 11:26:31AM -0500, Madison Kelly wrote: > Hi all, > > I have been -trying- to setup a server with a '/' filesystem of > 'reiserfs' for later use under LVM and some HA software but I have been > absolutely unable to get past the starting gate and on top of feeling > flat out stupid I am also getting terribly frustrated. > > I want to do one, little simple thing - make a backup of '/' to > another drive/partition and then reboot using it. It seems that > absolutely no matter what I do, what file I edit or what I try to force > the system (Fedora Core 1) INSISTS on using the original '/' (in this > case '/dev/sda1'). I don't what the heck I am doing wrong but I am about > to blow a gasket. I have never been so fsck'ing mad at Linux before. Why > is it so damn hard to mount a different '/' partition?! I assume backup went okey, and you're trying to boot from /dev/sdb1 (eg) instead of original /dev/sda1. 1. Locate grub.conf (or, whatever that is in grub) and search for root=/dev/sda1 and change it to '/dev/sdb1'. Then, write to MBR. 2. When you choose kernel from 'boot:' prompt (or, whatever), add kernel parameter as usual, ie. linux root=/dev/sdb1 3. Or, as last resort, write '/dev/sdb1' right into the kernel, using rdev vmlinuz /dev/sdb1 > > Anyway, I am using Grub because it is the only boot loader available > on Fedora. I have tried reading the docs and am doing so again after > sending this to see if I missed something simple... > > Bah, if nothing else this is a rant that may help me cool down enough > to find my problem. Sorry for the noise. > > Madison > > -- > The Toronto Linux Users Group. Meetings: http://tlug.ss.org > TLUG requests: Linux topics, No HTML, wrap text below 80 columns > How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml -- William Park, Open Geometry Consulting, <opengeometry-FFYn/CNdgSA at public.gmane.org> Linux solution for data management and processing. -- The Toronto Linux Users Group. Meetings: http://tlug.ss.org TLUG requests: Linux topics, No HTML, wrap text below 80 columns How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml

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