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..
I have a TCL framewrok for my test cases automation. This is been working for last 1 year. But yesterday it exited with exception when a function was called. The exception was given as fork: not enough memory while executing "spawn bash"(procedure "runtrigger" line 36) invoked from within "runtrigger $fnAfter $sid_l $mapver" ("trigger" arm line 6) invoked from within
View 4 Replies View RelatedI'm trying to write a program that will fork a series of FTP sessions. For each session, there should be separate input and output files associated with stdin and stdout/stderr.
I keep reading how I should be able to do that with dup2() in the child process before the execl(), but it's not working for me. Could someone please explain what I've done wrong? The program also has a 30-second sniper alarm for testing and killing of FTPs that go dormant for too long.
The code: (ftpmon.c)
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
[code]....
The output:
$ ftpmon
Connected to gila-crstest.gilacorp.com (172.16.20.8).
220 (vsFTPd 2.0.1)
ftp> waitpid(): Interrupted system call
Why am I getting the ftp> prompt? If the dup2() works, shouldn't it be taking input from my script and not my terminal? In stead, it does nothing, and winds up getting killed after 30 seconds. The log file is created, but it's empty after the run.
I am fairly new to linux still and I'm currently trying to write a shell script (which I have never done) that is supposed to run the xrestop(like top) program. What I want to do is execute the program and check the identifier column to see if a certain program is running. If it is running I want to strip the data from that row of the terminal say every 5 seconds or so and put it in a text file. Is this going to be a complicated thing?
Heres a list of the columns when you run xrestop program res-base Wins GCs Fnts Pxms Misc PxmMem Other Total PID Identifier.
I want to make alarm(buzzer) and Lamp(led) to work from infrared sensor output via usb.When ir sensor detect motion it will make the alarm&lamp on. Then also sending mail. Im using pic 18f2550-1/sp(usb Fsio from km2.net).But i dont know how to start the program.
View 2 Replies View RelatedAs 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]....
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].....
I was wanting to know what's a good programming suite that is comparable to MS Visual C++. I'm also curious about the portability of something I make in Linux, can I make a program in Linux and import it over to Windows, and what would be involved in making it compatible?
View 3 Replies View Relatedi have many text files in my directory and when i click on them to open them os treat it as a runnable file any says display or run or run in terminal ... i want to pick up recursively the tick of "Allow executing file as program" for all files.
View 2 Replies View RelatedAfter downloading any program thats in ubuntu or uses wine to run before i can run it i've got to allow it to execute, is there a workaround for this? Im using 10.04 ubuntu desktop
View 1 Replies View RelatedOn the `Install Properties` Menu , I am not allowed to check the: Allow executing file as program...
View 2 Replies View RelatedJust 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)
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.
View 1 Replies View RelatedAs 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.
View 3 Replies View RelatedI have been doing programming since the last 5 years. however, i have used to cut and paste the template without knowing in depth since i am chasing the time to finish a certain project. The title above seems easy if we read the manual, its just that im kinda confuse just for a second. Hope you guys can help me to give a better understanding for me so that i can upgrade my knowledge.Well, during my normal practice cut and paste, i try to understand this code below :-
Code: pid_t pid;
pid=fork();
if (pid < 0) {perror("Erro spawning process : "); exit(EXIT_FAILURE);}
[code]....
I m using ubuntu 10.04. I have install flightgear Scenery designer(fgsd) and it executed successfully, but during working on it I selected any option of it and fgsd crashed. After that it is not getting execute. Throwing following error on console. buffer overflow detected ***: fgsd terminated
View 1 Replies View RelatedI'm trying to run an application from the command prompt. I've set the path in .bashrc. My executable file and all other files needed by it are saved in the same directory as the path. When I enter the executable name to run it, I get an error message saying that the command is not found.
View 14 Replies View Relatedi got basic knowledge about creating a single child from a parent using fork(). But when it comes into creating multiple children, i am simply stuck. I am trying to create two processes from a parent and it would wait for both two processes to finish. my attempt is as below
[Code]....
Yesterday,I upgraded to ubuntu 10.10
then when i try to mark allow executing file as program it unmarks itself although i used it on ubuntu 10.4
I'm using Ubuntu and I'm programing with eclipse CDT. My goal is to execute a php file and read the output to my c++ program. To do so I thought I should use fork(), dup2() and execl. When in shell, the call "php myscript.php" worked just fine, but when in c++ I tried:
execl("usr/bin/php", "php", "home/geiger/workspace/SemiServer/server_content/myscript.php", NULL);
And it didn't work (the process wasn't terminated and I got no output). I tried different version of this call, like losing the "php" string and/or drop "home/geiger" from the path string, to no better result.
I'm wondering how python's thread & fork support is compared to perl? Which one is best option among Perl and Python
View 1 Replies View RelatedI know that fork() copies the address space of the calling process. Say, however, i have a linked list allocated. Will the list be copied over to the child process's space? If so, i would have to free them in the child process as well as the parent process, correct? Or will the variables be copied but not be pointing to any valid address? Or would it just kind of not do anything?example:
Code:
struct ll_ex {
struct ll_ex * next;
[code]....
Code:
int main()
{
int pi;
int i=10;
pid=fork();
[code]....
Q 1. The value of the variable pid returned by the fork() function will be greater than 0 in the parent process and equal to zero in the child process? but during forking, there values are exactly copied so what's went wrong here?
Q 2. "changes to the variable in one process is not reflected in the other process" why it is so? >> Even if we have variable i declared as a pointer or a global it wont make a difference.
Code:
int main()
{
int i, pid;
i=10;
printf("before fork i is %d
[code]....
Q. Through this program it is clear that both process is using the data from the same location, so where's the original value is residing when the child process is in execution.?
I have a monitoring program ( GIT link to sourceforge ) which I'm trying to use to track when a child exits/dies/whatever. I'm calling fork(), then close for 0,1,2, and then opening /dev/null, monitored.stdout, and monitored.stderr as a replacement. I'm not sure if I've done something incorrect (perhaps I should use dup2 for explicit assignment?) but it appears that printf() messages are just being blackholed. I've tried setting the line buffering as a last ditch effort. On a different system, using code similar to the spawn_monitor() function, this appears to work fine, which makes me think I'm relying on some implementation specific detail.
Relevant function, for those who don't click links:
Code:
26 int spawn_monitored(char *argv[])
27 {
28 int exit = 0;
29 pid_t child;
30 const struct rlimit inf = {
[code].....
I have been having some problems with virtualbox starting. So here is the issue: When I start a VM I get the following: Code: Kernel driver not installed (rc=-1908). The VirtualBox Linux kernel driver (vboxdrv) is either not loaded or there is a permission problem with /dev/vboxdrv. reinstall the kernel module by executing
[code]...
I am seeing quite a few entries about the usb. I am not sure if that is common or if its unrelated. I am running x86 11.3, and virtualbox 4.0.4 I have tried to uninstall, and even go back to 3.2
Why is the timer not executing?
Code: #include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <signal.h>
#include <time.h>
#include <pthread.h>
void func(union sigval sv)
[Code]....
what we are trying to do is, to let the customer click a button in the web browser, and then the web server to call a shell script to do the work. The output from the stdout && stderr of the script should be displayed in the web browser once finished or timeout, along with the exit code of the script.
The shell script is however not on the web server, but on another app server. So to call this script from the web server as the identity 'tomcat':
Code:
$ sh appuser@app-server:$appbin/app-script
The .ssh/id_rsa.pub thing is done, and we have no problem doing this in the command line so far.
Our loaded ex-colleage has left us the webpages (jsp) with code like these:
Code:
<%@ include file="jsp_functions.jsp" %>
<%
String cmd = "sh $appbin/app-script";
ExecResult r = new ExecResult();
[Code].....
I am having the following error while executing script and initialing my application
./ss.sh: line 1: kk.sh: command not found
./ss.sh: line 2: mon.exe: command not found
Can somebody assist ASAP.
I have an application, probably cpu-intensive because sometimes it leaves the cpu with 0% idle (in top). Sometimes it hangs ("Done" does not print) when executing this part, but most of the time it executes just fine. Is there any wrong with this code?
View 2 Replies View RelatedI need a way to read and delete text found before a unique string, then delete the string. I would like to have the text stored in a variable--or better yet--executed it as a shell script directly.I intend to execute the stored text in bash. It does not matter much what language the program is it, however efficiency is desirable. This script is not going to be used on large files, but it may be executed many times sequentially so the faster the script works the better. Here is an example:
exclamation-"It worked!"
echo $exclamation
cd
[code]....