LINUX programming Forum RSS Feed

Programs that will communicate via shared memory and semaphores.

Mon, 01 Mar 2010 03:48:58 -0700

Write 2 programs that will communicate via shared memory and semaphores. Data will be exchanged via memory and semaphores will be used to synchronise and notify each process when operations such as memory loaded and memory read have been performed.

Thnaking u
KRISH

How can I implement our own sleep call in c language?

Fri, 19 Feb 2010 08:56:13 -0700

Hoiiii

How can I implement our own sleep call in c language?

Any idea ...???

Thanking you,
Krish

What happens when a process executes unlink(".");

Fri, 19 Feb 2010 08:47:31 -0700

hiii

What happens when a process executes unlink(".");
What is the current directory of the process ? (Assume superuser permissions are given.)

Thanking you
Krish

Linux programming how to?

Sun, 14 Feb 2010 18:34:08 -0700

Dear friends ,

i am a wannabe linux programmer, i'm using ubuntu and wish to add a functionality like this :
the system should indicate the successful detection of usb device by a sound signal , please tell me how do i get started
i am a beginner in linux programming , please help me.

the clock_gettime sys call

Sun, 31 Jan 2010 20:22:52 -0700

Hi,
I was trying to use the clock gettime function as below .........

clock_gettime( CLOCK_REALTIME, &oldTime)

...but gettin an undefined reference to 'clock_gettime' error message....can't figure out why... I check the man pages and it needs time.h which has already been included in the code.... can someone help. Thanks

Regular expression, text replacement using simple edit

Sun, 31 Jan 2010 18:35:41 -0700

I'm trying to make a shell script that can change class names in source files.

The following will run without an error message but it doesn't do exactly what I want.

sed 's/from/to/g' somefile_containing_from.txt

That command will replace all occurrences of the word "from" to "to" while printing out the contents of the file. What I need is something where it only matches when there is a non-letter before and after the "from".

Due to the problem in the above command, the following undesired replacements happen:

File contents for student.java before running through sed command:

public class student
{
   private student[] topstudent;
}

using command:

sed 's/student/Student/g' student.java

Prints the following:

public class Student
{
   private Student[] topStudent;
}

Notice that the variable name changed because it found "student" in the output even though topstudent was not the class name.

Needed to compile my first kernel program

Thu, 14 Jan 2010 21:36:01 -0700

Please Help needed to compile my first kernel program

I have compile & install new kernel 2.6.32.3 on path: /root/linux2.6.32.3/
I have written small program [shown below] at path: /root/abc/

I already compile & install kernel 2.6.32.3 on fedora 10 machine & check /boot/grub/menu1.st entry it is there.

My program giving an error when I "make"
++++++++++++++++++++++++++++++++++++++++++++++++++ ++++++++++++++++

uname: extra operand `.r'
Try `uname --help' for more information.
uname: extra operand `.r'
Try `uname --help' for more information.
make: Nothing to be done for `all'.

++++++++++++++++++++++++++++++++++++++++++++++++++ ++++++++++++++++

My Kernel Program

++++++++++++++++++++++++++++++++++++++++++++++++++ +++++++++++++++++++++++++++++++++++++
/*
* hello.1.c . The simplest kernel module.
*/
#include </root/linux-2.6.32.3/include/linux/module.h> /* Needed by all modules */
#include </root/linux-2.6.32.3/include/linux/kernel.h> /* Needed for KERN_INFO */

int init_module(void)
{
printk(KERN_INFO "Hello world 1.\n");
/*
* A non 0 return means init_module failed; module can't be loaded.
*/
return 0;
}

void cleanup_module(void)
{
printk(KERN_INFO "Goodbye world 1.\n");
}

++++++++++++++++++++++++++++++++++++++++++++++++++ +++++++++++++++++++++++++++++++++++++++
Makefile look like

obj.m += hello.1.o
all:
make .C /lib/modules/$(shell uname .r)/build M=$(PWD) modules
clean:
make .C /lib/modules/$(shell uname .r)/build M=$(PWD) clean

++++++++++++++++++++++++++++++++++++++++++++++++++ ++++++++++++++++++++++++++++++++++++++++~
~

Please Help needed to compile my first kernel program

Thu, 14 Jan 2010 21:35:08 -0700

Please Help needed to compile my first kernel program

Thu, 14 Jan 2010 21:33:17 -0700

Linux on PowerPC: How to use timer interrupt?

Fri, 08 Jan 2010 07:14:17 -0700

Hello!

Nowadays I try to use PowerPC in Linux. I am porting some codes which were implemented for ARM core. In this code, it can set timer interrupt with micro time unit. In order to this, it uses OSCR, OSMR1, OIER registers, which exists in pxa270 Processor (ARM core)

Actually, I want to implement this function on PowerPC, but I think PowerPC doesn't provide registers for configuring timer interrupt.

The board which I use is GE Faunc VG5, and its mircoprocessor is PowerPC MPC7455. I read MPC7455 Manual, but I cannot find the register related to timer interrupt. There is only timer count clock register. (TBU and TBL)

So, what is the method of implementing timer interrupt in PowerPC?
If I want to make an interrupt after 200us, how can I implement it in Linux on PowerPC?

Please, if there are any one who knows well, let me know the method!

Have a good day!

How to migrate to Linux?

Thu, 31 Dec 2009 05:41:30 -0700

I use windows XP and want to migrate to linux OS. I want to migrate urgently because i m fed of viruses, slowing down of windows etc.Please your suggestions or experiences.

makefile to convert jpeg files to png files

Sun, 29 Nov 2009 16:16:04 -0700

Hello!

I'm desperately trying to write a makefile that converts and scales jpeg files to png files in subdirectories

I want to use netpbm, so I just need the commands:
anytopnm
pnmscale
pnmtopng

For various reasons i want to use a makefile. This is the first time i use the make tool and it's a too complicated for me.
Here is my attempt, without resizing untill now:

all :
    find -name "*.jpeg" > alljpeg.txt
    @anytopnm `cat alljpeg.txt | sort | uniq -u` > $@.png
    @echo "$@" >> clean.log

but it doesn't work, I already had six attempts but always the same, I'm reading now for 4 hours an I still think I#m not any closer to a solution.

Any help will be appreciated!

Clueless greetings

Henningbaer

About splice systemcall problem

Fri, 20 Nov 2009 03:35:59 -0700

hi,
while i was using splice system call for copy one file to another,
I got the error is given below:

splice() (from) failed: Invalid argument

In file:
int relay_fd,log_fd;
int pipe_fd[2];
int retval;
After open the files,

retval = splice(relay_fd, NULL, pipe_fd[1], NULL, 128, SPLICE_F_MOVE);

If you have any idea, please help me.

Regards,
manikandan

pthread_mutex_call blocks forever causing cpu usage 100%

Sun, 15 Nov 2009 21:55:43 -0700

pthread_mutex_lock() call never returns causing other threads to wait
for gaining its lock forever in turn causing 100% cpu load. I have tried
using alternate call pthread_mutex_trylock() which try to lock and if the
mutex is locked in some other thread it returns with an error code.

The above mentioned call pthread_mutex_lock is used in an application which
goes to full cpu load once mutex blocks forever, and even if i kill the application
and restart it, it will again go to full cpu load, the problem of full cpu load only gets
resolved when i restart the machine, is there any other alternate call or any other
possible solution for this problem.

hello

Tue, 10 Nov 2009 03:58:22 -0700

cheap sale
Welcome to our site: http://www.voguecatch.com

hello

Tue, 10 Nov 2009 03:56:48 -0700

cheap sale
Welcome to our site: http://www.voguecatch.com

My script returns an error when it doesn't like the input

Sat, 31 Oct 2009 16:24:49 -0700

I have a script which assigns the output of a shell command to a string, for later comparison.

The command typically outputs either "Idle" or
"Uploading 1 file (102.8 KB/sec, 1 min left)"

I use a test:

while test $status != 'Idle'

However, when the string is not equal to 'Idle' it crashes, possibly because of the unusual characters such as / and ( etc. in the alternative output.

Is it possible to compare or even prepare the string before comparison so that my script doesn't crash? Or is shell scripting limited in this way, in which case I should be using a different language?

Here is the script in case it makes things clearer. It's purpose is to start dropbox, allow it's running while it is performing any action, but exiting if everything is already up to date.

#! /bin/sh
dropbox start

status=$(dropbox status)

while test $status != 'Idle'
do
  echo "Working"
  status=$(dropbox status)
done

echo "\nIdle again.. exiting"
dropbox stop

(doubt) linux vs windows

Sat, 31 Oct 2009 12:50:40 -0700

how to write code for an application that makes it open source? hope, i am clear with my view.

i mean windows was written in C and its closed whereas linux written in c is open.where is the difference?

How to create "post-it" note? Also, use .odt or rtf?

Wed, 28 Oct 2009 20:27:45 -0700

We are designing a cross platform note application for Linux using wxWidgets in C++ or in Python.

But we have a few questions I need to try to find answers for.

1. should we use a RTF format for the notes, or should we try to use the open source format .odt? Our most important concern is that text formatting is preserved when users cut and paste from OpenOffice, Word, or from Firefox. Any recommendations on how to go about doing this?

2. We want to include a 'Post-It' note feature similar to that used in WORD (in Word they call it "add comment") or in Adobe Acrobat (where it is like a little yellow sticky note) You can click on the document and add a 'comment'. A yellow little box will pop up in which you can type the comment.
Any suggestions on how to make this?

question on use raw socket to a implement HTTP Proxy Server

Mon, 26 Oct 2009 09:20:19 -0700

Hi,

I am trying to implement a HTTP proxy server using raw socket.

I create a alias IP address on eth1:0 192.168.0.200 on my linux box

I opened a raw socket as:

fd = socket(AF_INET, SOCK_RAW, IPPROTO_RAW);

and binds to 192.168.0.200 and port 3080

bind(fd, (struct sockaddr *) &addr, sizeof(addr));

However when I use netstat it shows the port as 255 as the following:

raw 0 0 192.168.0.200:255 0.0.0.0:* 7 7469/test-http-proxy

I changed the Firefox connection settings to Manual proxy configuration as:

HTTP Proxy: 192.168.0.200 Port:3080

I got this error from Firefox, and I did not receive any packets from the raw socket.

The browser is configured to use a proxy server, but the proxy refused a connection.

* Is the browser's proxy configuration correct? Check the settings and try again.
* Does the proxy service allow connections from this network?
* Still having trouble? Consult your network administrator or Internet provider for assistance.

Any ideas or pointers are appreciated.

yu_zyy

BASH: SED/AWK A Variable

Wed, 14 Oct 2009 00:38:32 -0700

Hi Im wondering how to extract data from a variable. I have a variable that contains YYYYMMDD, something like 20091013. Can I extract the year, YYYY, to varA, the month, MM, to varB and the day, DD to vabC?

BASH: Script Input Flags

Mon, 12 Oct 2009 21:11:49 -0700

Hi. Im wondering if there is a way to use flags when starting a script.
Something like this.

Script -a -b 10

Right now Ive got something like this.

while getopts ab AA
   do case $AA in
       a) var="value"
       ;;
   esac
done

So with that code I can only use flags ( -a -b ). Can I do the -b 10 so it will store say varB=10?

Migrating my site from Ubuntu 9.04 to RedHat 5 - directory issues

Tue, 06 Oct 2009 08:32:00 -0700

Hi All,
I'm attempting to migrate my website files from server Ubuntu 9.04 to RedHat 5. it's currently hosted in directory
\var\www\intranet

but in RedHat 5 the root directory is
\var\www\documents\intranet

I just want to know if avoioding/ignoring the document directory and placing my intranet folder in the same www directory will cause problems.
Any assistance appreciated!

Samsung S3C2416 + Android = Embedded Solution

Thu, 24 Sep 2009 20:41:06 -0700

Samsung S3C2416 + Android + Embedded Solution

A Cost-effective Solution, applied to industrial control, power, medical, media, communications, security, automotive, financial services, consumer electronics, handheld devices, teaching and other fields for the control panel, terminal, POS, terminal delivery, human-computer interaction interface.

For more information, please visit:
http://www.giayee.com/solutions/S3C2416%20Solution.asp

Marvell PXA310 + Android = Cellular & Handheld Solutions

Thu, 24 Sep 2009 20:38:21 -0700

Marvell PXA310 + Android = Cellular & Handheld Solutions

The PXA310 processor joins the PXA3xx processor family as a cost-effective solution with up to 806 MHz of power-efﬁcient compute performance, hardware video acceleration, and DRM security, enabling the development of cost-efficient smartphones, industrial embedded solutions, and handheld devices.

For more information, please visit:
http://www.giayee.com/solutions/PXA310%20Solutions.asp