I need help with this sample application. When I run it, it gets stuck after the child process prints "Child sending!".
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <stdlib.h>
#include <string.h>
#define INPUT 0
#define OUTPUT 1
int main()
{
...
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Hope I can find some help here cause I'm starting to give up. Heads up as this is an homework assignment, hence why it might be stupid.
Context:
Have to program something which ... |
I seem to be having trouble with pipe and select.
Context: Have to program something which will be shell executed as such:
logn [--tick n] cmd [args] [, cmd [args]]...
Basically, it's ... |
I'm implementing piping on a simulated file system in C++ (with mostly C). It needs to run commands in the host shell but perform the piping itself on the simulated ... |
I want to be able to fork a process and have the child and parent have a bi-directional link using pipes. I create 2 pipes and make parent read from the ... |
I am trying to implement something that will give me a solution for:
| --> cmd3 --> cmd4 -->
cmd2-->|
...
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I have created two processes using fork(). The child process is producing and writing continuously a variable amount of data (array char) to the pipe. The parent process reads from the ... |
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I'm trying to do a simple fork -> execute another program -> say "hello" to that child process -> read back something -> print what received.
The program used as child just ... |
I wrote a little program using fork to create new processes which use pipes to communicate. Applying defensive programming, I check every return value. If a return value indicates that something ... |
Hello all, Hope you are all doing well. I am very new to c programming and I have a task where I must make three (or more forks) communicate with the process that created them. I used a for loop to create the forks, which did fine. However, when trying to communicate, I used pipes (on the basis of FIFO), but ... |
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#include #include #include #include #define MAX 512 void make_trivial_ring(){ int fd[2]; pipe (fd); dup2(fd[0], STDIN_FILENO); dup2(fd[1], STDOUT_FILENO); close(fd[0]); close(fd[1]); } void add_new_node(int *pid){ int fd[2]; pipe (fd); *pid = fork(); if (*pid > 0) dup2(fd[1], STDOUT_FILENO); else dup2(fd[0], STDIN_FILENO); close(fd[0]); close(fd[1]); } int main(int argc, char *argv[ ]) { int k, i, childpid; int maxpid, maxnode, maxnum; ... |
Hi, Can anyone help me with my assignment? "Write a program in C which creates a child (with the use of fork) and between the child and the parent there is bidirectional communication through the use of pipes. The child process will read letters from the user (keyboard) and it will send them to the father. If the father process finds ... |
Hi, I'm developing a simple shell in C but I'm experiencing some problems to execute pipe separated commands properly, such as: 'env | sort' and others which make usage of the pipe '|'. As you may know, the pipe is the redirection of the stdout of the first command to the stdin of the second command. Therefore, in my program, when ... |
crazy pipe/fork hi i have a problem with either my forking or pipe which i cant spot or get my head around . Right here is my fork code: right what this is supposed to do is when I run the program "./spool 3" for instance it is meant to make 3 child processes and put them on the fifo pipe ... |
marktee() { pid_t pid; int i; int pi[2]; int fi[2]; int status; pipe(pi); pipe(fi); for(i=0; i<2 && (pid=fork()); i++); if(i==0 && pid==0) { printf("Child 1\n"); close(fi[0]); dup2(pi[1],1); close(pi[1]); execlp("/usr/bin/tee","tee","t1.txt",0); } if(i==1 && pid==0) { printf("Child 2 \n"); //close(pi[1]); close(fi[0]); dup2(pi[0],0); dup2(fi[1],1); close(fi[1]); execlp("/usr/bin/tee","tee","t2.txt",0); } else { printf("Parent\n"); close(pi[0]); close(pi[1]); close(fi[1]); dup2(fi[0],0); execl("/usr/bin/tee","tee","t3.txt",0); wait(&status); } |
You can't. IIRC, each write() is atomic. So if you prepare what you want to write in a buffer, then use a single write() call to write it, then that data will be read at the other end of the pipe as a contiguous block (that is, not mixed up with anyone elses write calls). |
18. fork and pipe cboard.cprogramming.com |
Hello all, Hope you are all doing well. I am very new to c programming and I have a task where I must make three (or more forks) communicate with the process that created them. I used a for loop to create the forks, which did fine. However, when trying to communicate, I used pipes (on the basis of FIFO), but ... |
Hi Everyone, I'm (yet again) having some problems, I've successfully got a parent and child to talk to one another using fork() and pipe(). I have also closed off stdin, stdout and stderr and now send them over to the parent, where they will be logged. What I want to do is check if the stderr pipe is active (i.e. that ... |
You're creating the pipe after the fork. Both the child and the parent are creating their own pipes rather than sharing a single pipe. Also, your code would be a lot more legible if cleaned up those if statements. If you get an error condition, just return from the function or use separate ifs for each condition. This makes it obvious ... |
What this code does is, parent process forks a child and then child forks a child. Parent writes a string to the pipe, child reads it and then writes it to the next pipe, the one connecting child and child's child. Child's child reads it and prints it in stdout Code: #define BSIZ 20 int fdpipe[2][2]; int main(){ pipe(fdpipe[0]); if(fork()!=0){//parent close(fdpipe[0][0]); ... |
#include #include #include #include #include #include #include #include #include #define SIZE 60 int main (int argc, char* argv[]){ int fdfork, fdfile,fdf; int pfd[argc - 3][2]; char temp_arr[SIZE]; int i,k,j; //in order to create son processes and pipe matrix for all son for(i = 0 ; i < argc-3 ; i++){ if(pipe(pfd[i]) == ... |
hi.......We have a task to write a program in C in linux environment that takes 2 command line arguments: 1.the name of a text file that contains single-digit integer data in one line 2.an integer to be searched from the sorted version of data in file. The prgram creates a child process that reads the text file paased as the first ... |
You are welcome. What do you mean? Threads are called threads in all systems I know, including POSIX-based. When I started to work with Linux, there were only processes; and threads were introduced later. Old processed could be understood like newer single-thread-only process. The units of execution are always threads; processes just host one ore more thread and provide complete data ... |