pttodo-cli default file via env

cmd/pttodo-cli/cli.go

@@ -22,7 +22,11 @@ func main() {
 }
 
 func _main() error {
-	filepath := flag.String("f", "-", "path to yaml file")
+	defaultFilepath, ok := os.LookupEnv("PTTODO_FILE")
+	if !ok {
+		defaultFilepath = "-"
+	}
+	filepath := flag.String("f", defaultFilepath, "($PTTODO_FILE) path to yaml file")
 	e := flag.Bool("e", false, "edit file")
 	flag.Parse()
 	if *e {