General :: How To Use Fork In My Programme
Aug 31, 2009
1) Write a C program using the fork() system call that that generates the Fibonacci sequence in the child process. The number of the sequence will be provided in the command line. For example, if 5 is provided, the first five numbers in the Fibonacci sequence will be output by the child process. Because the parent and child processes have their own copies of the data, it will be necessary for the child to output the sequence. Have the parent invoke the wait() call to wait for the child process to complete before exiting the program. Perform necessary error checking to ensure that a non-negative number is passed on the command line.
2) Repeat the preceding exercise, this time using the CreateProcess () in the Win32 API. In this instance, you will need to specify a separate program to be invoked from CreateProcess(). It is this separate program that will run as a child process outputting the Fibonacci sequence. Perform necessary error checking to ensure that a non-negative number is passed on the command line.i have done with Fibonacci sequence .but i dont know how to include tht fork() function and win32 api .any one can help to finish?
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Sep 21, 2010
When opening ubuntu live cd it appears to me as an operative system. Can it replace an os OR SHOULD IT BE USED ALONG WITH A SUITABLE OS? If it is the second option then what system to adopt? At present Ihave an XP prf.
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Apr 25, 2011
i just can't know how to get it work.
Code: #include<stdio.h>
main()
{
int _res;int i=3;int b=5;
asm_ ("add %1,%0"
:"=d"(_res):"a" (b),"0" (i));
printf("%d",_res);
}
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Aug 19, 2010
I've a script that forks to another script.
The problem is that the child will not return to main process.
Main script "fork.sh"
Code:
The child process "smb_fork.sh"
Code:
when running it from the terminal "sh -x ./foork.sh"
Code:
My goal is via cron connect to ~100 remote winXP computers and download a single file. There fore I like to fork the process.
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Aug 2, 2011
trying to fork multiple child but the program does not go as i want...
My code :
Code:
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
[code].....
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Mar 18, 2011
my code is very simple:
int pid, status;
printf("parent process id=%d, to call fork
",getpid());
if(pid=fork()<0)
[Code].....
but everytime I can only get two fork return pid=0. In parent process, the pid returned by fork() should be >0 and equal to the child process id.
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Apr 30, 2010
I am continuously getting fork: resources temporarily unavailable even when I am typing ls command.
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Sep 26, 2010
I am working on a project where I need to use the C language to generate a tree of processes. I understand how fork() works but I cant seem to get fork() to create two children from one parent and then have the two children create two more children.
Right now what i am seeing is a chain...where the parent creates one child...and that child creates another ONE child..etc.
Here is what I have so far:
for (i=0; i<n;i++){
if (childpid = fork()) break;
}
if (childpid == -1){
perror ("
[Code]....
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Aug 31, 2010
I would like to run versions of Mozilla Firefox 3.6.5+ as a single process, just as it was in versions 3.6.3 and prior. The reason is that, on Linux, I am running within proxychains - which doesn't bind to forked processes. Because the plugins in versions 3.6.5+ run in a forked process I can't use proxychains to redirect Flash streams. Is there a setting in modern versions of Firefox that allow me to run plugins in the main process?
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May 6, 2011
When a application is ran from the shell:fork() is calledexecve() is calledI know the shell stats the file to make sure the required permissions are allowed in the child shell. But I can not find this in the man fork. Nor can I find this in man execve. Which one of these processes/calls stats the binary to be ran?
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Jun 17, 2010
I am quite confused about the following description on fork. Could you please explain it ?The child process shall have its own copy of the parent's file descriptors. Each of the child's file descriptors shall refer to the same open file description with the corresponding file descriptor of the parent.For example, I am opening a socket and then fork. Now, does the child have a separate socket or is shares it with the parent. Does I have any impact on using it in child?
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May 13, 2011
I am new to linux. I want to make use of an ".so" module in my python programme. I have successfully installed the ".so" module by a setup file. But when I try to import the ".so" module in my python programme I am getting an error like ImportError: /usr/local/lib64/python2.5/site-packages/_first.so: undefined symbol: __fread_chk.I am working on opensuse server. Please let me know if you require any further information.
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Jul 19, 2011
Is that possible to ssh to a box and launch a programme, say firefox, have the session disconnet when not using it and then you can reconnect to the same session again?
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Dec 31, 2010
I've written a simple program in C++ that I want the system to launch each time I turn the ubuntu system on. Any idea how to do this?(I'm not an expert either so please be explicit )
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Sep 23, 2010
i want to spawn the browser in c programme like qtp & selenium.
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Aug 20, 2011
I am new at Centos. Sometimes my programme gives segmentation fault. This line is from it:./hlds_run: line 321: 5680 Segmentation fault $HL_CM
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Nov 20, 2009
I m newbie in Linux os & i need help from all of you so please help me on this issue.i'm Unable to see minim ize programe on desktop bar.please have a look on image.9 programes running but
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Aug 11, 2010
I have a programme known as OpenRep which can be launched by executing the file named OpenRep.jar by OpenJDK Java 6 Runtime programme This programme can also be launched through terminal by the command
Code:
java -jar OpenRep.jar
The location of the programme is in my Home folder. Well I would like to create a launcher for that programme.
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Oct 23, 2010
good programme that the volume control on the keyboard can work on the master control?
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Oct 13, 2010
I discovered that if you install directFB (a framebuffer display library magic thing) you can run "links -g" which makes an attempt to be graphical, but it's still not quite the same as a normal browser... I was wondering if there was any way to run an X server for a single programme, or an equivalent solution. Essentially, what I'd like to be able to do is run, say, "startx firefox [URL] and for an X server to be created solely to run my firefox instance. Obviously, the current behaviour (at least, in Ubuntu, as I haven't installed X on Gentoo) is to bring up a graphical login screen, allowing me to start an entirely new X session. Is there a way to do this, or is it just "not how X works"?
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Nov 24, 2009
I am trying to download a programme from the BBC iplayer, using get_iplayer version 2.48. I get an error message saying that it needs rtmpdump >= 1.5, or flvstreamer. I have rtmpdump version 1.4 installed, but can't find either rtmpdump>=1.5 or flvstreamer for opensuse (11.1).
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Jan 20, 2010
Occasionally my mouse and touchpad freeze. How can I kill an open programme with the keyboard (in Karmic Koala)?
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Mar 31, 2011
I was wondering if any free, small, portable, cross platform programme exists for encrypting/decrpyitng simple txt files?
I know a couple of small ones for windows systems (nosee, dscrypt) but i wonder if there is any i could use on both linux and windows OS. the idea is to be able to carry it on USB key and the programme (or probably there will have to be 2 versions of it) would run either on windows or linux os and i could decrypt and encrypt the file if i needed to. no matter on what system i plug the USB key to.
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Sep 16, 2010
As part of my ongoing project I need to put together a messaging server of sorts. So far I have coded a server which accepts multiple connections, which then runs a function that will perform a task, see below.On this sever I have a global structure which is populated using the data found in a read() buffer. However with each fork() that runs the below function each process is handed a blank structure. How could I go about allowing each fork() child process access the same structure?
My code should hopefully show what I am trying to do?
Code: void listen_for_client(int sock)
{
[code]....
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Apr 10, 2011
Now,I created one parent and two children. I must create some value as random in child1 and child1 has to send these values to child2.Child2 must read them.. now,I cant create some random values and i can send them.But child2 doesnt work. I have two functions. One them is writing, another one is reading. Child2 uses reading function,but it doesnt work (child2 cant call it, because writing function in endless loop) What i must do? I used wait,usleep... No way.. I attached my file and also there is code..
PHP Code: #include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <signal.h>
#include <stdarg.h>
#include <sys/types.h>
[Code].....
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Feb 10, 2010
I realize the information found here is potentially biased, but it made me curious where Fedora stands. Now that even Debian has agreed to distribute the original fork of Cdrtools, is Fedora considering that option? Several other distros are distributing the original fork now, and it's where active development is ongoing.
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Sep 30, 2010
Just coming over from Windows here... where I've been using "CreateProcess" which returns a value depending on whether the process was created successfully or not.
Now I'm trying to create a process on linux and I've been learning about fork/exec, and I've been struggling with the fact that there seems to be no easy way to know (within the original parent process) if exec succeeded or not. (without forcing the parent process to hang around polling it or something).
Anyway, I've now just discovered the posix_spawn function, and it seems exactly what I need. However I'm finding the documentation a little hard to understand. In particular, I can't find actual confirmation that it will definitely return an error if creating the process fails (like CreateProcess does on windows). So can anyone confirm that for me?
The text on the documentation states: "If posix_spawn() or posix_spawnp() fail for any of the reasons that would cause fork() or one of the exec family of functions to fail, an error value shall be returned as described by fork() and exec"
This makes me think it uses exec/fork under the hood, and so I wonder if it can be trusted..?
And also, most of the examples on the internet for creating processes use fork/exec, so I wonder if there is some catch with posix_spawn I haven't read about... (since it seems a much simpler way of doing things)
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Aug 19, 2010
I have been struggling with this for about a week now. I'm working with QuickUSB to send video streams to and from a device. I get the fastest results by fork()ing and exec()ing new processes everytime I run a pipeline, which works great when reading from files, but now i have to transition it so that i am reading/writing data over a QuickUSB bus. I have it working for each individual process, but i can't run multiple processes because it won't let me open the device. After looking through QuickUSB's API a little closer, i found that the QHANDLE type that they use to describe the usb device is actually just a usb_dev_handle *. From what i have found, this is an incomplete structure, so i am having trouble with opening it in the main process and passing it to each new process to write to it. I already have semaphores set up to prevent multiple processes using it at the same time. I just CANT find out how to utilize the same usb device between two process that are forked and exec. i also must do the exec() because otherwise my gtk and gstreamer fails for trying to share resources.
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Oct 23, 2010
As an assignment i was doing a program to create two process using fork and pass messages between them using message queue.Did it worked well until my friend tried to copy it using scp.suddenly all hell broke loose as processes without ran syncronisation ie. in tech terms the process just wont wait wen a message queue is empty.it keeps on executing randomly.but after a reboot .. everything worked fine. until again i tried to do scp on my system on purpose. and again the program just went mad.
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May 25, 2011
I am learning about OS and I wrote this simple forking program... Here's the code..
Code:
#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
[Code].....
How can it print the first statement, that is BEFORE the fork() statement twice?
I am running Natty 11.04 btw..
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