管道通信——Pipeline communication

//using pipe the communication between f proccess and c proc
//
//
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/wait.h>

#define BUFSIZE 1024

int main()
{
int ret,retw;
pid_t pid;
char buf[BUFSIZE] = {'\0'};
int pd[2];

// pipe() creates a pair of file descriptors, pointing to a pipe inode, and places them in the
// array pointed to by filedes. filedes[0] is for reading, filedes[1] is for writing.

if(pipe(pd) < 0)
{
perror("pipe()");
exit(1);
}

pid = fork();
if(pid < 0)
{
perror("fork()");
exit(1);
}

if(pid == 0) //child read
{
close(pd[1]); //prevent the error
ret = read(pd[0],buf,BUFSIZE);
puts(buf);
close(pd[0]);
exit(0);
}
else // parent write
{
close(pd[0]);
retw = write(pd[1],"Hello",5);
close(pd[1]);
wait(NULL);
exit(0);
}

exit(0);
}