#include<iostream>
#include<unistd.h>
#include<stdlib.h>
#include <sys/types.h>
int main()
{
int fd[2]{};
int nret=pipe(fd);
pid_t pid=fork();
if(pid==-1)
perror("fork faild!");
else if(pid==0)
{
close(fd[0]);
dup2(fd[1],STDOUT_FILENO);
int n=execlp("ls","ls",NULL);
if(n==-1)
{
perror("execlp faild!");
exit(1);
}
}
else
{
close(fd[1]);
dup2(fd[0],STDIN_FILENO);
execlp("wc","wc","-l",NULL);
}
}