4 files changed, 19 insertions, 7 deletions
diff --git a/Makefile b/Makefile
index 7939343..c6d6a61 100644
--- a/Makefile
+++ b/Makefile
@@ -6,7 +6,7 @@ run: clean build
 	make -C testSort/
 
 test:
-	./autogenpb --proto test.proto
+	./autogenpb --dry-run --proto test.proto --lobase gitTag --upbase GitTag --sort "ByPath,Refname"
 
 vet:
 	@GO111MODULE=off go vet
diff --git a/argv.go b/argv.go
index 41af3c3..fb1eedd 100644
--- a/argv.go
+++ b/argv.go
@@ -12,6 +12,8 @@ type args struct {
 	LoBase string `arg:"--lobase"                   help:"lowercase basename"`
 	UpBase string `arg:"--upbase"                   help:"uppercase basename"`
 	Proto  string `arg:"--proto"                    help:"the .proto filename"`
+	Sort   []string `arg:"--sort"                    help:"how and what to sort on"`
+	DryRun    bool   `arg:"--dry-run"                      help:"show what would be run"`
 }
 
 func (a args) Description() string {
diff --git a/main.go b/main.go
index 5390e9c..1f0f6b9 100644
--- a/main.go
+++ b/main.go
@@ -26,7 +26,9 @@ func main() {
 
 	if !shell.Exists(argv.Proto) {
 		log.Info("protobuf", argv.Proto, "is missing")
-		os.Exit(-1)
+		if ! argv.DryRun {
+			os.Exit(-1)
+		}
 	}
 
 	if !strings.HasSuffix(argv.Proto, ".proto") {
@@ -50,8 +52,6 @@ func main() {
 
 	protobase := strings.TrimSuffix(argv.Proto, ".proto")
 
-	f, _ := os.OpenFile(protobase+".sort.pb.go", os.O_WRONLY|os.O_CREATE, 0600)
-
 	sortmap := make(map[string]string)
 	sortmap["package"] = packageName
 	sortmap["base"] = argv.LoBase
@@ -59,8 +59,18 @@ func main() {
 	sortmap["Base"] = argv.UpBase
 	sortmap["Bases"] = sortmap["Base"] + "s"
 
-	sortmap["sortBy"] = "ByPath"
-	sortmap["sortKey"] = "Refname"
+	sortparts := strings.Split(argv.Sort[0], ",")
+	sortmap["sortBy"] = sortparts[0]
+	sortmap["sortKey"] = sortparts[1]
+
+	if argv.DryRun {
+		for k, v := range sortmap {
+			log.Info(k, "=", v)
+		}
+		os.Exit(0)
+	}
+
+	f, _ := os.OpenFile(protobase+".sort.pb.go", os.O_WRONLY|os.O_CREATE, 0600)
 
 	header(f, sortmap)
 	syncLock(f, sortmap)
diff --git a/testautogen/Makefile b/testautogen/Makefile
index 534167e..4cde6ea 100644
--- a/testautogen/Makefile
+++ b/testautogen/Makefile
@@ -6,7 +6,7 @@ test: vet
 all: clean test.pb.go run goimports vet
 
 run:
-	../autogenpb --proto test.proto --lobase gitTag --upbase GitTag
+	../autogenpb --proto test.proto --lobase gitTag --upbase GitTag --sort "ByPath,Refname"
 
 vet:
 	@GO111MODULE=off go vet