write short readme section about accounts

README.md

@@ -18,6 +18,7 @@ See TODO.md for a list of known issues and future work I've curated, or go to th
     * [Client patch directories for PC and BB](#client-patch-directories)
     * [How to connect](#how-to-connect)
 * Features and configuration
+    * [User licenses](#user-licenses)
     * [Installing quests](#installing-quests)
     * [Item tables and drop modes](#item-tables-and-drop-modes)
     * [Cross-version play](#cross-version-play)
@@ -223,6 +224,12 @@ For GC clients, you'll have to use newserv's built-in DNS server or set up your
 
 # Server feature configuration
 
+## User licenses
+
+By default, newserv does not require users to pre-register before playing; the server will instead automatically create an account the first time each player connects. These accounts have no special permissions. You can view, create, edit, and delete user accounts in the server's shell (run `help` in the shell to see how to do this).
+
+If you're running the server not only for yourself, you may want to give your account elevated privileges. To do so, run `update-license SERIAL-NUMBER flags=root` (replacing SERIAL-NUMBER with your actual serial number). You can also use update-license to edit other parts of the license; for example, if you want your GC and BB characters to share an account so they will have the same Guild Card number and privilege flags, you can run `update-license SERIAL-NUMBER bb-username=USERNAME bb-password=PASSWORD`.
+
 ## Installing quests
 
 newserv automatically finds quests in the subdirectories of the system/quests/ directory. To install your own quests, or to use quests you've saved using the proxy's Save Files option, just put them in one of the subdirectories there and name them appropriately. The subdirectories and their behaviors (e.g. in which game modes they should appear and for which PSO versions) is defined in the QuestCategories field in config.json.

src/ServerShell.cc

@@ -451,9 +451,14 @@ CommandDefinition c_list_licenses(
     List all licenses registered on the server.",
     true,
     +[](CommandArgs& args) {
-      for (const auto& l : args.s->license_index->all()) {
-        string s = l->str();
-        fprintf(stderr, "%s\n", s.c_str());
+      auto licenses = args.s->license_index->all();
+      if (licenses.empty()) {
+        fprintf(stderr, "No licenses registered\n");
+      } else {
+        for (const auto& l : licenses) {
+          string s = l->str();
+          fprintf(stderr, "%s\n", s.c_str());
+        }
       }
     });