Better usage message for mtredisalize

main.go

@@ -20,6 +20,13 @@ const (
 	GCDuration = "24h"
 )
 
+func usage() {
+	fmt.Fprintf(os.Stderr,
+		"Usage: %s [<options>] <database>\n", os.Args[0])
+	fmt.Fprintln(os.Stderr, "Options:")
+	flag.PrintDefaults()
+}
+
 func main() {
 
 	var (
@@ -32,6 +39,8 @@ func main() {
 		gcDuration  string
 	)
 
+	flag.Usage = usage
+
 	flag.IntVar(&port, "port", 6379, "port to bind")
 	flag.StringVar(&driver, "driver", "leveldb", "type of database (leveldb, sqlite)")
 	flag.StringVar(&host, "host", "", "host to bind")