diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..d616c8c
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+xsum
diff --git a/Makefile b/Makefile
index a1ba2b8..c099c92 100644
--- a/Makefile
+++ b/Makefile
@@ -13,7 +13,7 @@ GOFLAGS = -ldflags "$(GOLDFLAGS)"
 default: rundebug
 
 rundebug: build
-	DEBUG=1 ./xsum
+	./xsum -d
 
 run: build
 	./xsum
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..f19164c
--- /dev/null
+++ b/main.go
@@ -0,0 +1,128 @@
+package main
+
+//import "crypto/sha256"
+import "fmt"
+import "github.com/sirupsen/logrus"
+
+//import "github.com/pkg/xattr"
+import "hash"
+import "os"
+import "flag"
+import "time"
+
+var Version string
+var Buildtime string
+var Builduser string
+var Buildarch string
+var log *logrus.Logger
+
+func main() {
+	os.Exit(xsum())
+}
+
+func xsum() int {
+	log = logrus.New()
+	log.SetLevel(logrus.ErrorLevel)
+	log.SetReportCaller(false)
+	debugPtr := flag.Bool("d", false, "debug mode")
+	flag.Parse()
+	if *debugPtr == true {
+		log.SetReportCaller(true)
+		log.SetLevel(logrus.DebugLevel)
+	}
+
+	log.Debugf(
+		"xsum version %s (%s) built %s by %s",
+		Version,
+		Buildarch,
+		Buildtime,
+		Builduser,
+	)
+
+	paths := flag.Args()
+	fmt.Printf("%+v\n", paths)
+	if len(paths) > 1 {
+		paths = paths[1:]
+	}
+	fmt.Printf("%+v\n", paths)
+	switch flag.Arg(0) {
+	case "cron":
+		return xsfCheckAndUpdate(paths)
+	case "check-and-update":
+		return xsfCheckAndUpdate(paths)
+	case "check":
+		return xsfCheck(paths)
+	case "update":
+		return xsfUpdate(paths)
+	default:
+		usage()
+		return -1
+	}
+}
+
+func usage() {
+	fmt.Fprintf(os.Stderr, "usage: %s [-d] <update|check|check-and-update|cron> <path> [path2] [...]\n", os.Args[0])
+	flag.PrintDefaults()
+}
+
+func xsfCheck(paths []string) int {
+	log.Debugf("check")
+	return 0
+}
+
+func showError(e *error) {
+	fmt.Fprintf(os.Stderr, "error: %s\n", e)
+}
+
+func xsfUpdate(paths []string) int {
+	log.Debugf("update")
+	for _, path := range paths {
+		x := NewXsf(path)
+		err := x.Update()
+		if err != nil {
+			showError(&err)
+			return -1
+		}
+	}
+	return 0
+}
+
+func xsfCheckAndUpdate(paths []string) int {
+	log.Debugf("check-and-update")
+	r := xsfCheck(paths)
+	if r != 0 {
+		return r
+	}
+	return xsfUpdate(paths)
+}
+
+type xsf struct {
+	path  string
+	mtime *time.Time
+	size  int64
+	sum   *hash.Hash
+	fi    *os.FileInfo
+}
+
+func (x *xsf) Update() error {
+	fp, e1 := os.Open(x.path)
+	defer fp.Close()
+	if e1 != nil {
+		return e1
+	}
+
+	fi, e2 := fp.Stat()
+	if e2 != nil {
+		return e2
+	}
+	x.size = fi.Size()
+	t := fi.ModTime()
+	x.mtime = &t
+	return nil
+}
+
+func NewXsf(path string) *xsf {
+	x := xsf{}
+	x.path = path
+	return &x
+}