diff --git a/env/env.go b/env/env.go
index 6874ab0..11545c1 100644
--- a/env/env.go
+++ b/env/env.go
@@ -1,19 +1,23 @@
 package env
 
 import (
+	"fmt"
 	"github.com/guonaihong/flag"
 	"os"
+	"os/exec"
+	"strings"
 )
 
 type Env struct {
 	IgnoreEnvironment bool   `opt:"i, ignore-environment" usage:"start with an empty environment"`
 	Unset             string `opt:"u, unset" usage:"remove variable from the environment"`
-	Chdir             string `opt:"C, chdir" usage:"change working directory to DIR"`
-	Null              byte   `opt:"0, null" usage:"end each output line with NUL, not newline"`
+	//Chdir             string `opt:"C, chdir" usage:"change working directory to DIR"`
+	Null bool `opt:"0, null" usage:"end each output line with NUL, not newline"`
 }
 
 func Main(argv []string) {
 	var env Env
+	delimiter := byte('\n')
 
 	command := flag.NewFlagSet(argv[0], flag.ExitOnError)
 	command.ParseStruct(argv[1:], &env)
@@ -23,18 +27,34 @@ func Main(argv []string) {
 		os.Clearenv()
 	}
 
-	for _, v := range args {
-		kv, err := strings.Split(v, "=")
-		if err != nil {
-			//todo
+	if env.Null {
+		delimiter = byte(0)
+	}
+
+	for k, v := range args {
+		if strings.IndexByte(v, '=') > 0 {
+			kv := strings.SplitN(v, "=", 2)
+			if err := os.Setenv(kv[0], kv[1]); err != nil {
+				fmt.Printf("%s\n", err)
+			}
+			continue
 		}
-		if err = os.Setenv(kv[0], kv[1]); err != nil {
-			//todo
+
+		cmd := exec.Command(args[k], args[k+1:]...)
+		cmd.Stdout = os.Stdout
+		cmd.Stdin = os.Stdin
+		cmd.Stderr = os.Stderr
+		err := cmd.Run()
+		if err != nil {
+			fmt.Printf("%s\n", err)
+			os.Exit(1)
 		}
+
+		os.Exit(0)
 	}
 
 	allArgs := os.Environ()
 	for _, v := range allArgs {
-		fmt.Fprintf(os.Stdout, "%s\n", v)
+		fmt.Fprintf(os.Stdout, "%s%c", v, delimiter)
 	}
 }