+static int help(void) {
+
+ printf("%s [OPTIONS...] {COMMAND} ...\n\n"
+ "Send control commands to or query the login manager.\n\n"
+ " -h --help Show this help\n"
+ " --version Show package version\n"
+ " --no-pager Do not pipe output into a pager\n"
+ " -a --all Show all properties, including long and unprintable\n"
+ " -f --follow Follow journal\n"
+ " -o --output=STRING Change output mode (short, verbose, export, json)\n",
+ program_invocation_short_name);
+
+ return 0;
+}
+
+static int parse_argv(int argc, char *argv[]) {
+
+ enum {
+ ARG_VERSION = 0x100,
+ ARG_NO_PAGER
+ };
+
+ static const struct option options[] = {
+ { "help", no_argument, NULL, 'h' },
+ { "version" , no_argument, NULL, ARG_VERSION },
+ { "no-pager", no_argument, NULL, ARG_NO_PAGER },
+ { "follow", no_argument, NULL, 'f' },
+ { "output", required_argument, NULL, 'o' },
+ { "all", no_argument, NULL, 'a' },
+ { NULL, 0, NULL, 0 }
+ };
+
+ int c;
+
+ assert(argc >= 0);
+ assert(argv);
+
+ while ((c = getopt_long(argc, argv, "hfo:a", options, NULL)) >= 0) {
+
+ switch (c) {
+
+ case 'h':
+ help();
+ return 0;
+
+ case ARG_VERSION:
+ puts(PACKAGE_STRING);
+ puts(DISTRIBUTION);
+ puts(SYSTEMD_FEATURES);
+ return 0;
+
+ case ARG_NO_PAGER:
+ arg_no_pager = true;
+ break;
+
+ case 'f':
+ arg_follow = true;
+ break;
+
+ case 'o':
+ if (streq(optarg, "short"))
+ arg_output = OUTPUT_SHORT;
+ else if (streq(optarg, "verbose"))
+ arg_output = OUTPUT_VERBOSE;
+ else if (streq(optarg, "export"))
+ arg_output = OUTPUT_EXPORT;
+ else if (streq(optarg, "json"))
+ arg_output = OUTPUT_JSON;
+ else {
+ log_error("Unknown output '%s'.", optarg);
+ return -EINVAL;
+ }
+ break;
+
+ case 'a':
+ arg_show_all = true;
+ break;
+
+ case '?':
+ return -EINVAL;
+
+ default:
+ log_error("Unknown option code %c", c);
+ return -EINVAL;
+ }
+ }
+
+ return 1;
+}
+