[avatars] section in modopts.ini now used for 2 things:

default import/export sub-board (default to 'syncdata')
export_freq (default: 7 days)

The user avatars export frequency is now controlled and
user avatars should not be exported unless they've been
recently created or updated or the configured frequency
has elapsed.

There's currently no export frequency control for
collections (ever time you export a .bin file, it'll be exported to
the msg base)

exec/avatars.js

 // $Id$
 
 var REVISION = "$Revision$".split(' ')[1];
+
 load('sbbsdefs.js');
 load("lz-string.js");
 var lib = load({}, 'avatar_lib.js');
 var SAUCE = load({}, 'sauce_lib.js');
 
+var export_freq = 7;	// minimum days between exports
+
+var options=load({}, "modopts.js", "avatars");
+if(!options)
+	options = {};
+if(!options.sub)
+    options.sub="syncdata";
+if(options && options.export_freq > 0)
+	export_freq = options.export_freq;
+
 const user_avatars = 'SBBS User Avatars';
 const shared_avatars = 'SBBS Shared Avatars';
 
@@ -255,7 +266,7 @@ function decompress_list(list)
 	return new_list;
 }
 
-function export_users(msgbase, realnames)
+function export_users(msgbase, realnames, all)
 {
 	var last_user = system.lastuser;
 	var list = {};
@@ -270,18 +281,39 @@ function export_users(msgbase, realnames)
 		if(u.settings&USER_DELETED)
 			continue;
 		var avatar = lib.read_localuser(n);
-		if(!avatar)
+		if(avatar.export_count == undefined)
+			avatar.export_count = 0;
+		if(!lib.enabled(avatar)) {
 			continue;
-		var data = LZString.compressToBase64(base64_decode(avatar.data));
-		if(!list[data])
-			list[data] = [];
-		list[data].push(u.alias);
-		if(realnames)
-			list[data].push(u.name);
-		exported++;
+		}
+		var last_exported = 0;
+		if(avatar.last_exported)
+			last_exported = new Date(avatar.last_exported);
+		var updated;
+		if(avatar.updated)
+			updated = new Date(avatar.updated);
+		else
+			updated = new Date(avatar.created);
+		if(all == true
+			|| updated > last_exported
+			|| new Date() - last_exported >= export_freq * (24*60*60*1000)) {
+			printf("Exporting avatar for user #%u\r\n", n);
+			var data = LZString.compressToBase64(base64_decode(avatar.data));
+			if(!list[data])
+				list[data] = [];
+			list[data].push(u.alias);
+			if(realnames)
+				list[data].push(u.name);
+			avatar.last_exported = new Date();
+			avatar.export_count++;
+			lib.write_localuser(n, avatar);
+			exported++;
+		}
 	}
-	if(!exported)
+	if(!exported) {
+		print("No avatars to export");
 		return true;	// Nothing to export
+	}
 	for(var i in list)
 		list[i].sort();
 	var body = "json-begin\r\n";
@@ -379,7 +411,7 @@ function main()
 				printf("%s\r\n", success ? "Successful" : "FAILED!");
 				break;
 			}
-			var msgbase = new MsgBase(optval[cmd]);
+			var msgbase = new MsgBase(optval[cmd] ? optval[cmd] : options.sub);
 			print("Opening msgbase " + msgbase.file);
 			if(!msgbase.open()) {
 				alert("Error " + msgbase.error + " opening msgbase: " + msgbase.file);
@@ -389,7 +421,7 @@ function main()
 			msgbase.close();
 			break;
 		case "export":
-			var msgbase = new MsgBase(optval[cmd]);
+			var msgbase = new MsgBase(optval[cmd] ? optval[cmd] : options.sub);
 			print("Opening msgbase " + msgbase.file);
 			if(!msgbase.open()) {
 				alert("Error " + msgbase.error + " opening msgbase: " + msgbase.file);
@@ -398,7 +430,7 @@ function main()
 			var success = true;
 			if(!files.length) {
 				printf("Exporting user avatars\n");
-				success = export_users(msgbase, realnames);
+				success = export_users(msgbase, realnames, all);
 			}
 			for(var i in files) {
 				printf("Exporting avatar file: %s\n", files[i]);