Add dirname

README.md

@@ -11,3 +11,4 @@ Implemeted utilities:
  * `true`
  * `false`
  * `yes`
+ * `dirname`

dirname/dirname.go

@@ -0,0 +1,20 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"path"
+)
+
+func usage() {
+	fmt.Printf("usage: %v path\n", os.Args[0])
+}
+
+func main() {
+	if len(os.Args) != 2 {
+		usage()
+		os.Exit(1)
+	}
+
+	fmt.Println(path.Dir(os.Args[1]))
+}