diff --git a/README.md b/README.md
index 2397563..14a9026 100644
--- a/README.md
+++ b/README.md
@@ -26,8 +26,8 @@ $ go test -v ./...
       private key password with decrypt usage
     -i file path
       source file path
-    -o file path
-      output file path
+    -o [file path|-]
+      output file path or stdout
     -k file path
       key file path
 ```
\ No newline at end of file
diff --git a/libs/flag.go b/libs/flag.go
index dbba7b1..96b0666 100644
--- a/libs/flag.go
+++ b/libs/flag.go
@@ -23,12 +23,13 @@ func RegFlag(f *Flags) {
 	flag.BoolVar(&f.Decrypt, "d", false, "decrypt file")
 	flag.BoolVar(&f.Encrypt, "e", false, "encrypt file")
 	flag.StringVar(&f.SrcFile, "i", "", "input source `file path`")
-	flag.StringVar(&f.DstFile, "o", "", "output `file path`")
+	flag.StringVar(&f.DstFile, "o", "", "output `[file path|-]`")
 	flag.StringVar(&f.KeyFile, "k", "", "key `file path`")
 	flag.BoolVar(&f.Override, "y", false, "if output file exists override")
 	flag.StringVar(&f.Password, "p", "", "private key password")
 }
 
+// ToMap - flags struct to map
 func (f *Flags) ToMap() map[string]interface{} {
 	t := reflect.ValueOf(f).Elem()