/* implement '/bin/ps -ef | /bin/more' */
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
int st;

main() {
  int fds[2];
  char *argv[3];
  pipe(fds); 
  if (fork() == 0) {
    close(0); dup(fds[0]);        /* redirect standard input to fds[1] */
    close(fds[0]); close(fds[1]); /* close unused files */
    argv[0] = "/bin/more"; argv[1] = 0;
    if (execv(argv[0], argv) == -1) {
      printf("/bin/more failed\n");
    }
    exit(0);
  } if (fork() == 0) {
    close(1); dup(fds[1]);        /* redirect standard output to fds[0];*/
    close(fds[0]); close(fds[1]); /* close unused files */
    argv[0] = "/bin/ps"; argv[1] = "-ef"; argv[2] = 0;
    if (execv(argv[0], argv) == -1) {
      printf("/bin/ps failed\n");
    }
    exit(0);
  }
  close(fds[0]); close(fds[1]);
  wait(&st); wait(&st);
}