pipe.c

#include<stdio.h>
#include <sys/wait.h>
       #include <assert.h>
       #include <stdio.h>
       #include <stdlib.h>
       #include <unistd.h>
       #include <string.h>

       int
       main(int argc, char *argv[])
       {
           int pipefd[2];
           pid_t cpid;
           char buf;

           assert(argc == 2);

           if (pipe(pipefd) == -1) {
               perror("pipe");
               exit(EXIT_FAILURE);
           }

           cpid = fork();
           if (cpid == -1) {
               perror("fork");
               exit(EXIT_FAILURE);
           }

           if (cpid == 0) {    /* Child reads from pipe */
               close(pipefd[1]);          /* Close unused write end */

               while (read(pipefd[0], &buf, 1) > 0)
                   write(STDOUT_FILENO, &buf, 1);

               write(STDOUT_FILENO, "\n", 1);
               close(pipefd[0]);
               _exit(EXIT_SUCCESS);

           } else {            /* Parent writes argv[1] to pipe */
               close(pipefd[0]);          /* Close unused read end */
               write(pipefd[1], argv[1], strlen(argv[1]));
               close(pipefd[1]);          /* Reader will see EOF */
               wait(NULL);                /* Wait for child */
               exit(EXIT_SUCCESS);
           }
       }