#include <stdlib.h>
#include <stdio.h>
const char *cmd1[] = { "/bin/ps", "-e",  0 };
const char *cmd2[] = { "/usr/bin/wc", "-l",  0 };
int fd[2];
//ipc-shell-2.c
void runpipe()
{
	int pid;
	switch (pid = fork()) {
	   case 0: dup2(fd[0], 0); 
		   close(fd[1]);	
		   execvp(cmd2[0], cmd2); 
		   perror(cmd2[0]);
	   default: dup2(fd[1], 1);  
		    close(fd[0]);	
		    execvp(cmd1[0], cmd1);
		    perror(cmd1[0]); break;
	   case -1: perror("fork"); exit(1);
	}
}
int main()
{
	int pid, status;
	pipe(fd);
	switch (pid = fork()) {
	   case 0:  runpipe(); exit(0);
	   default: wait(); break;
	   case -1: perror("fork"); exit(1);
	}
	exit(0);
}