diff --git a/src/rt/shell/fs/search.ts b/src/rt/shell/fs/search.ts
index d032d81..92a53c0 100644
--- a/src/rt/shell/fs/search.ts
+++ b/src/rt/shell/fs/search.ts
@@ -1,5 +1,6 @@
 interface Search {
 	binary: <T>(list: T[], find: T) => T | undefined,
+	binary_nsort: <T>(list: T[], find: T, start: number, end: number) => T | undefined;
 	linear: <T>(list: T[], find: T) => T | undefined,
 }
 const search = {} as Search
@@ -12,15 +13,22 @@ search.binary = function(list, find) {
 		const median = (start+end)>>1
 		if (list[median] === find) {
 			return find
-		} else if (list[median]<find) {
-			start = median+1
-		} else {
-			end = median-1
-		}
+		} else if (list[median]<find) { start = median+1 } else { end = median-1 }
 	}
 	return
 }
 
+search.binary_nsort = function(list, find, start = 0, end = list.length-1) {
+	if (start>end) { return }
+	const median = (start+end)>>1
+	if (list[median] === find) { return list[median] }
+	if (list[median]>find) {
+		return this.binary_nsort(list, find, start, median-1)
+	} else {
+		return this.binary_nsort(list, find, median+1, end)
+	}
+}
+
 search.linear = function(list, find) {
 	for (const item of list) {
 		if (item === find) {