#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 pfd[2];
    pid_t cpid;
    char buf;

    assert(argc == 2);

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

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

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

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

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

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