swaybar: add --help option

swaybar/main.c

@@ -1191,6 +1191,7 @@ int main(int argc, char **argv) {
 	bool debug = false;
 
 	static struct option long_options[] = {
+		{"help", no_argument, NULL, 'h'},
 		{"version", no_argument, NULL, 'v'},
 		{"socket", required_argument, NULL, 's'},
 		{"bar_id", required_argument, NULL, 'b'},
@@ -1198,10 +1199,23 @@ int main(int argc, char **argv) {
 		{0, 0, 0, 0}
 	};
 
+	const char *usage =
+		"Usage: swaybar [options...] <output>\n"
+		"\n"
+		"  -h, --help             Show help message and quit.\n"
+		"  -v, --version          Show the version number and quit.\n"
+		"  -s, --socket <socket>  Connect to sway via socket.\n"
+		"  -b, --bar_id <id>      Bar ID for which to get the configuration.\n"
+		"  -d, --debug            Enable debugging.\n"
+		"\n"
+		" PLEASE NOTE that swaybar will be automatically started by sway as\n"
+		" soon as there is a 'bar' configuration block in your config file.\n"
+		" You should never need to start it manually.\n";
+
 	int c;
 	while (1) {
 		int option_index = 0;
-		c = getopt_long(argc, argv, "vs:b:d", long_options, &option_index);
+		c = getopt_long(argc, argv, "hvs:b:d", long_options, &option_index);
 		if (c == -1) {
 			break;
 		}
@@ -1224,6 +1238,7 @@ int main(int argc, char **argv) {
 			debug = true;
 			break;
 		default:
+			fprintf(stderr, "%s", usage);
 			exit(EXIT_FAILURE);
 		}
 	}