这就是我想做的:
我尝试编写一个程序,创建带有两个子级的父级,父级创建未命名管道,写入其中,子级应该从中读取(每1个字节),然后在两个不同的终端窗口中输出结果。我不知道如何同步它们。
我在一个终端窗口中得到类似这样的信息:Nejke aa 第二个:adt 我想要:Nejake 数据
我尝试在互联网上搜索,但我还是想问。 非常感谢任何帮助。
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <sys/stat.h>
/* declare our procedures */
void runchild1(int pfd[]);
void runchild2(int pfd[]);
/* some data to write and read from pipe */
const char some_data[] = "Nejake data" ;
int main(int argc, char **argv)
{
int pid, status; //PID for debugging
int fd[2]; //file descriptors for the pipe
/* let create some pipe */
pipe(fd);
/* supposed to run two children of the process */
runchild1(fd);
runchild2(fd);
/* this is important! close both file descriptors on the pipe */
close(fd[0]); close(fd[1]);
/* pick up all the dead children */
while ((pid = wait(&status)) != -1)
fprintf(stderr, "process %d exits with %d\n", pid, WEXITSTATUS(status));
exit(0);
}
void runchild1(int pfd[]) /* run the first child */
{
int pid; /* you may want to print it for debugging */
int data_processed; /* store data */
int des; /* descriptor for open files */
char buffer; /* buffer for reading byte of data */
switch (pid = fork()) {
case 0: /* child reads from the pipe */
close(pfd[1]); /* this process don't need the other end */
while ((data_processed = read(pfd[0],&buffer,1)) > 0) {
printf("Proces %d, data citane po bajte: %c\n",getpid(),buffer);
des = open("/dev/ttys001",O_RDWR);
write(des, &buffer,1);
}
exit(0);
default: /* parent writes to the pipe */
/* write some data for children to read */
data_processed = write(pfd[1], some_data, strlen(some_data));
printf("Zapis %d bytov cez nepomenovanu ruru:\n", data_processed);
printf("Zapisane: %s\n",some_data);
printf("Som rodic dvoch deti: %d\n",getpid());
break;
case -1:
perror("fork");
exit(1);
}
}
void runchild2(int pfd[]) /* run the second child */
{
int pid;
int data_processed;
int des;
char buffer;
switch (pid = fork()) {
case 0: /* child */
close(pfd[1]); /* this process doesn't need the other end */
while ((data_processed = read(pfd[0],&buffer,1)) > 0) {
printf("Proces %d, data citane po bajte: %c\n",getpid(),buffer);
des = open("/dev/ttys002",O_RDWR);
write(des, &buffer,1);
}
exit(0);
default: /* parent does nothing */
break;
case -1:
perror("fork");
exit(1);
}
}
最佳答案
如果两个子级都需要查看相同的数据,则需要两个管道,每个子级一个,并且父级必须将每条消息写入两次,每个管道一次。
或者,您可以运行 tee
命令为 process substitution ,或者您可以查找(尝试查找)程序 pee
(tee
的进程/管道变体) - 或者您可以点击此 Stack Overflow answer 中的链接。您的程序将有一根 pipe ,但 children 最终将拥有自己的 pipe 。
关于c - 两个 child 在 pipe 里读书,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/15731790/