better usage error text

1 files changed, 8 insertions, 5 deletions

diff --git a/main.go b/main.go
index f50704b..1b43031 100644
--- a/main.go
+++ b/main.go
@@ -18,6 +18,12 @@ func fmtDuration(d time.Duration) string {
 	return fmt.Sprintf("%02d:%02d:%02d", h, m, s)
 }
 
+func errusage(msg string) {
+	fmt.Fprintf(os.Stderr, "%s: %s\n", os.Args[0], msg)
+	usage(os.Stderr)
+	os.Exit(2)
+}
+
 func usage(w io.Writer) {
 	fmt.Fprintf(w, "Usage: %s refs/FROM_REFNAME refs/TO_PREFIX\n", os.Args[0])
 	fmt.Fprintf(w, "   or: %s -h|--help\n", os.Args[0])
@@ -33,15 +39,12 @@ func main() {
 		}
 	}
 	if len(os.Args) != 3 {
-		usage(os.Stderr)
-		os.Exit(2)
+		errusage("wrong number of arguments")
 	}
 	fromRef := os.Args[1]
 	toPfx := os.Args[2]
 	if !strings.HasPrefix(fromRef, "refs/") || !strings.HasPrefix(fromRef, "refs/") {
-		fmt.Fprintln(os.Stderr, "ref names and prefixes must start with \"refs/\"")
-		usage(os.Stderr)
-		os.Exit(2)
+		errusage("ref names and prefixes must start with \"refs/\"")
 	}
 
 	commits := 0