redirect_dup2    1860 process.c                  ret = redirect_dup2(pairs[j].oldfd, pairs[j].newfd);
redirect_dup2    1897 process.c                  ret = redirect_dup2(pairs[i].oldfd, extra_fd);
redirect_dup2    1905 process.c                  ret = redirect_dup2(pairs[j].oldfd, pairs[j].newfd);
redirect_dup2    1965 process.c                      ret = redirect_dup2(fd2, fd);