ignores short and long parameters

example_test.go

@@ -496,3 +496,19 @@ func Example_allSupportedTypes() {
 
 	// output:
 }
+
+func Example_envVarOnly() {
+	os.Args = split("./example")
+	_ = os.Setenv("NUM_WORKERS", "my_key")
+
+	defer os.Unsetenv("NUM_WORKERS")
+
+	var args struct {
+		AuthKey string `arg:"-,--,env:NUM_WORKERS"`
+	}
+
+	MustParse(&args)
+
+	fmt.Println(args.AuthKey)
+	// output: my_key
+}

parse.go

@@ -360,11 +360,6 @@ func cmdFromStruct(name string, dest path, t reflect.Type) (*command, error) {
 			case strings.HasPrefix(key, "--"):
 				spec.long = key[2:]
 			case strings.HasPrefix(key, "-"):
-				if len(key) != 2 {
-					errs = append(errs, fmt.Sprintf("%s.%s: short arguments must be one character only",
-						t.Name(), field.Name))
-					return false
-				}
 				spec.short = key[1:]
 			case key == "required":
 				spec.required = true