pw_checkfd
int pw_checkfd(char *nptr);
fd = pw_checkfd(optarg);
fd = pw_checkfd(optarg);
fd = pw_checkfd(optarg);
fd = pw_checkfd(optarg);
fd = pw_checkfd(optarg);
fd = pw_checkfd(optarg);
fd = pw_checkfd(optarg);
fd = pw_checkfd(optarg);