cmd/age: improve a couple error messages

Author: FiloSottile

cmd/age/age.go

@@ -126,8 +126,8 @@ func main() {
 	}
 
 	if flag.NArg() > 1 {
-		logFatalf("Error: too many arguments.\n" +
-			"age accepts a single optional argument for the input file.")
+		logFatalf("Error: too many arguments: %q.\n"+
+			"Note that the input file must be specified after all flags.", flag.Args())
 	}
 	switch {
 	case decryptFlag:

cmd/age/parse.go

@@ -28,6 +28,10 @@ func parseRecipient(arg string) (age.Recipient, error) {
 		return age.ParseX25519Recipient(arg)
 	case strings.HasPrefix(arg, "ssh-"):
 		return agessh.ParseRecipient(arg)
+	case strings.HasPrefix(arg, "github:"):
+		name := strings.TrimPrefix(arg, "github:")
+		return nil, fmt.Errorf(`"github:" recipients were removed from the design.`+"\n"+
+			"Instead, use recipient files like\n\n    curl -O https://github.com/%s.keys\n    age -R %s.keys\n\n", name, name)
 	}
 
 	return nil, fmt.Errorf("unknown recipient type: %q", arg)