Тестовые примеры / ch8 / command_pipe2

	#include <stdio.h>

	#include <stdlib.h>

	#include <sys/types.h>

	#include <sys/wait.h>

	#include <unistd.h>

	#define CLOSE(fd)  if (fd < -1) close(fd), fd=-1

	static int fifo[2][2] = { -1, -1, -1, -1 }, cur_pipe=0;



	int main( int argc, char* argv[]) 

	{

			for (int i=1; i < argc; i++) 

			{

				if (pipe(fifo[cur_pipe])) perror("pipe"), _exit(2); 

				switch (fork()) 					/* execute command to the left of pipe */

				{

					case -1:			perror("fork"), exit(3);

					case 0	:		if (i > 1) 	/* not  first command */

								{

									dup2(fifo[1-cur_pipe][0],STDIN_FILENO);

									CLOSE(fifo[1-cur_pipe][0]);

								}

								if (i < argc-1)		/* not the last command */

								{

									dup2(fifo[cur_pipe][1],STDOUT_FILENO);

									CLOSE(fifo[cur_pipe][0]);

									CLOSE(fifo[cur_pipe][1]);

								}

								if (execlp("/bin/sh","sh","-c",argv[i],0)==-1)

									perror("execl"), exit(5);

				}

				CLOSE(fifo[1-cur_pipe][0]);

				CLOSE(fifo[cur_pipe][1]);

				cur_pipe = 1 - cur_pipe;

			}

			CLOSE(fifo[1-cur_pipe][0]);

			while (waitpid(-1,0,0)) ;

			return 0;

	}