Тестовые примеры / ch8 / command_pipe

		#include <stdio.h>

		#include <stdlib.h>

		#include <unistd.h>

		#include <sys/types.h>

		#include <sys/wait.h>

		#define CLOSE_ALL()  close(fifo[0]), close(fifo[1]) 



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

		{

				int 	fifo[2];

				pid_t	pid1, pid2;



				if(pipe(fifo)) perror("pipe"), _exit(2); 	/* create a command pipe */



				switch (pid1=fork()) 					/* execute command to the left of pipe */

				{

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

					case 0:			if (dup2(fifo[1],STDOUT_FILENO)==-1)

									perror("dup2"), exit(4);

								CLOSE_ALL();

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

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

				}



				switch (pid2=fork()) 					/* execute command to the right of pipe */

				{

					case -1:			perror("fork"), exit(6);

					case 0	:		if (dup2(fifo[0],STDIN_FILENO)==-1)

									perror("dup2"), exit(7);

								CLOSE_ALL();

								if (execlp("/bin/sh","sh","-c",argv[2],0)==-1)

									perror("execl"), exit(8);

				}



				CLOSE_ALL();

				if (waitpid(pid1,&fifo[0],0)!=pid1 || waitpid(pid2,&fifo[1],0)!=pid2)

					perror("waitpid");

				return fifo[0]+fifo[1];

		}