diff --git a/cmd/conf.go b/cmd/cfg.go
similarity index 93%
rename from cmd/conf.go
rename to cmd/cfg.go
index 855a261..a61dc30 100644
--- a/cmd/conf.go
+++ b/cmd/cfg.go
@@ -7,7 +7,7 @@ import (
 
 var (
 	confCmd = &cobra.Command{
-		Use:   "conf",
+		Use:   "cfg",
 		Short: "change config",
 		Args:  cobra.ExactArgs(2),
 		Run: func(cmd *cobra.Command, args []string) {
diff --git a/conf/conf.go b/conf/conf.go
index 3e48ae1..6fe0cf7 100644
--- a/conf/conf.go
+++ b/conf/conf.go
@@ -11,10 +11,9 @@ import (
 )
 
 const (
-	Version        = "0.1.1"
-	SepGroupInFile = "_"
-	SepInCmd       = ","
-
+	Version          = "0.1.1"
+	SepGroupInFile   = "_"
+	SepInCmd         = ","
 	BaseHostFileName = "base"
 	HostFileExt      = ".txt"
 	OpEditor         = "editor"
@@ -93,7 +92,11 @@ func Sync() {
 	}
 
 	// todo writer interface
-	if err := cfg.SaveTo(ConfigFile); err != nil {
+	cfgFile, err := hfs.H.Create(ConfigFile)
+	if err != nil {
+		display.ErrExit(err)
+	}
+	if _, err = cfg.WriteTo(cfgFile); err != nil {
 		display.ErrExit(err)
 	}
 }
diff --git a/conf/unix.go b/conf/unix.go
index 2c6510f..1c202fa 100644
--- a/conf/unix.go
+++ b/conf/unix.go
@@ -3,15 +3,8 @@
 
 package conf
 
-import (
-	"golang.org/x/text/encoding/unicode"
-)
-
 const (
-	SysHost = "/etc/hosts"
-	NewLine = "\n"
-)
-
-var (
-	SysHostCharset = unicode.UTF8
+	SysHost       = "/etc/hosts"
+	NewLine       = "\n"
+	DefaultEditor = "vim"
 )
diff --git a/conf/windows.go b/conf/windows.go
index 51d299b..a680232 100644
--- a/conf/windows.go
+++ b/conf/windows.go
@@ -3,13 +3,8 @@
 
 package conf
 
-import "golang.org/x/text/encoding/charmap"
-
 const (
-	SysHost = "C:\\Windows\\System32\\drivers\\etc\\hosts"
-	NewLine = "\r\n"
-)
-
-var (
-	SysHostCharset = charmap.ISO8859_1
+	SysHost       = "C:\\Windows\\System32\\drivers\\etc\\hosts"
+	NewLine       = "\r\n"
+	DefaultEditor = "notepad"
 )
diff --git a/hfs/hfs.go b/hfs/hfs.go
index 4c32c82..ece794c 100644
--- a/hfs/hfs.go
+++ b/hfs/hfs.go
@@ -25,7 +25,6 @@ type Hfs interface {
 	fs.FS
 	fs.ReadDirFS
 	fs.ReadFileFS
-	OpenFile(name string, flag int, perm os.FileMode) (*os.File, error)
 	WriteFile(path string, data []byte, perm os.FileMode) error
 	MkdirAll(path string, perm os.FileMode) error
 	Stat(path string) (fs.FileInfo, error)
diff --git a/hfs/memfs.go b/hfs/memfs.go
index 1794a43..2d2a2a0 100644
--- a/hfs/memfs.go
+++ b/hfs/memfs.go
@@ -28,11 +28,6 @@ type MemFs struct {
 	rootDir *MemDir
 }
 
-func (m *MemFs) OpenFile(name string, flag int, perm os.FileMode) (*os.File, error) {
-	//TODO implement me
-	panic("mem fs not support OpenFile method")
-}
-
 func (m *MemFs) NewFs() Hfs {
 	return &MemFs{
 		rootDir: &MemDir{
diff --git a/hfs/memfs_test.go b/hfs/memfs_test.go
index 31d6723..617b490 100644
--- a/hfs/memfs_test.go
+++ b/hfs/memfs_test.go
@@ -1,3 +1,6 @@
+//go:build memfs
+// +build memfs
+
 /*
  @Author: ingbyr
 */
diff --git a/hfs/osfs.go b/hfs/osfs.go
index 34c7c75..3854186 100644
--- a/hfs/osfs.go
+++ b/hfs/osfs.go
@@ -18,10 +18,6 @@ var H Hfs = NewOsFs()
 type OsFs struct {
 }
 
-func (o *OsFs) OpenFile(name string, flag int, perm os.FileMode) (*os.File, error) {
-	return os.OpenFile(name, flag, perm)
-}
-
 func (o *OsFs) NewFs() Hfs {
 	panic("os fs do not support NewFs() method")
 }
diff --git a/host/manager.go b/host/manager.go
index 5805e6d..23ebed3 100644
--- a/host/manager.go
+++ b/host/manager.go
@@ -8,7 +8,6 @@ import (
 	"bufio"
 	"bytes"
 	"fmt"
-	"os"
 	"sort"
 	"strings"
 
@@ -296,11 +295,11 @@ func (m *manager) ApplyGroup(group string, simulate bool) {
 	}
 
 	// open system host file
-	sysHost, err := fs.OpenFile(conf.SysHost, os.O_RDONLY|os.O_WRONLY|os.O_TRUNC, hfs.Perm644)
-	defer sysHost.Close()
+	sysHost, err := fs.Create(conf.SysHost)
 	if err != nil {
 		display.ErrExit(err)
 	}
+	defer sysHost.Close()
 
 	// write hosts to system host file
 	if _, err = sysHost.Write(combinedHostContent); err != nil {