diff --git a/main.go b/main.go
index e80efc6..e0c44a6 100644
--- a/main.go
+++ b/main.go
@@ -1,12 +1,11 @@
 package main
 
 import (
-	"bytes"
 	"encoding/csv"
 	"flag"
 	"fmt"
-	"io"
 	"log"
+	"os"
 	"sort"
 	"strconv"
 	"time"
@@ -21,6 +20,8 @@ func init() {
 func main() {
 
 	cfAPIKey := flag.String("cfapikey", "", "in cf, my profile -> API Tokens -> Create Token")
+	onlyZone := flag.String("onlyZone", "", "if specified, only the zone with this name will be processed. If omitted, all zones will be processed")
+	outFile := flag.String("outFile", "cfcleaner.csv", "the path of the output file")
 	flag.Parse()
 
 	if *cfAPIKey == "" {
@@ -38,6 +39,9 @@ func main() {
 	outRows := make([]cf.Record, 0)
 
 	for _, zone := range zones {
+		if *onlyZone != "" && zone.Name != *onlyZone {
+			continue
+		}
 		log.Printf("processing zone '%s' with ID '%s'", zone.Name, zone.ID)
 
 		records, err := cfClient.GetRecords(zone)
@@ -60,20 +64,25 @@ func main() {
 		return outRows[i].NumberQueries < outRows[j].NumberQueries
 	})
 
-	buf := bytes.NewBuffer(nil)
-	writer := csv.NewWriter(buf)
-	writer.Write([]string{"Name", "Type", "NumberQueries", "CreatedOn", "ModifiedOn", "Comment", "Content"})
+	f, err := os.OpenFile(*outFile, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0600)
+	if err != nil {
+		log.Fatalf("failed to open output file '%s': %v", *outFile, err)
+	}
+	defer f.Close()
+
+	writer := csv.NewWriter(f)
+	defer writer.Flush()
+	err = writer.Write([]string{"Name", "Type", "NumberQueries", "CreatedOn", "ModifiedOn", "Comment", "Content"})
+	if err != nil {
+		log.Fatalf("failed to write to outFile: %v", err)
+	}
 
 	for _, row := range outRows {
-		writer.Write([]string{row.Name, row.Type, strconv.Itoa(row.NumberQueries), row.CreatedOn.Format(time.RFC3339), row.ModifiedOn.Format(time.RFC3339), row.Comment, row.Content})
-	}
-	writer.Flush()
-
-	b, err := io.ReadAll(buf)
-	if err != nil {
-		log.Fatalf("failed to read bytes from output buffer: %v", err)
+		err = writer.Write([]string{row.Name, row.Type, strconv.Itoa(row.NumberQueries), row.CreatedOn.Format(time.RFC3339), row.ModifiedOn.Format(time.RFC3339), row.Comment, row.Content})
+		if err != nil {
+			log.Fatalf("failed to write to outFile: %v", err)
+		}
 	}
 
-	fmt.Println(string(b))
-
+	fmt.Printf("wrote to file: %s\n", *outFile)
 }