diff --git a/pkg/clierrors/common.go b/pkg/clierrors/common.go
index 7bf2065..7a2f3a7 100644
--- a/pkg/clierrors/common.go
+++ b/pkg/clierrors/common.go
@@ -5,11 +5,3 @@ type Interrupted struct{}
 func (e Interrupted) Error() string {
 	return "interrupted"
 }
-
-type UnknownCommand struct {
-	Command string
-}
-
-func (e UnknownCommand) Error() string {
-	return "unknown command: " + e.Command
-}
diff --git a/pkg/clierrors/common_test.go b/pkg/clierrors/common_test.go
index 5619829..3ea3979 100644
--- a/pkg/clierrors/common_test.go
+++ b/pkg/clierrors/common_test.go
@@ -2,15 +2,6 @@ package clierrors
 
 import "testing"
 
-func TestUnknownCommand_Error(t *testing.T) {
-	command := "test"
-	err := UnknownCommand{Command: command}
-	expected := "unknown command: " + command
-
-	if err.Error() != expected {
-		t.Errorf("Expected error message '%s', but got '%s'", expected, err.Error())
-	}
-}
 func TestInterrupted_Error(t *testing.T) {
 	err := Interrupted{}
 	expected := "interrupted"
diff --git a/pkg/clierrors/network.go b/pkg/clierrors/network.go
deleted file mode 100644
index 4ee25cf..0000000
--- a/pkg/clierrors/network.go
+++ /dev/null
@@ -1,13 +0,0 @@
-package clierrors
-
-type ConnectionClosed struct{}
-
-func (e ConnectionClosed) Error() string {
-	return "connection closed"
-}
-
-type Timeout struct{}
-
-func (e Timeout) Error() string {
-	return "timeout"
-}
diff --git a/pkg/clierrors/network_test.go b/pkg/clierrors/network_test.go
deleted file mode 100644
index aaad9ec..0000000
--- a/pkg/clierrors/network_test.go
+++ /dev/null
@@ -1,21 +0,0 @@
-package clierrors
-
-import "testing"
-
-func TestConnectionClosed_Error(t *testing.T) {
-	err := ConnectionClosed{}
-	want := "connection closed"
-
-	if got := err.Error(); got != want {
-		t.Errorf("Error() = %v, want %v", got, want)
-	}
-}
-
-func TestTimeout_Error(t *testing.T) {
-	err := Timeout{}
-	want := "timeout"
-
-	if got := err.Error(); got != want {
-		t.Errorf("Error() = %v, want %v", got, want)
-	}
-}
diff --git a/pkg/command/commands.go b/pkg/command/commands.go
index 456cf23..d1f8b77 100644
--- a/pkg/command/commands.go
+++ b/pkg/command/commands.go
@@ -48,7 +48,7 @@ type Executer interface {
 // If the command is not recognized, an error is returned.
 func Factory(raw string, macro *Macro) (Executer, error) {
 	if raw == "" {
-		return nil, fmt.Errorf("empty command")
+		return nil, &ErrEmptyCommand{}
 	}
 
 	parts := strings.SplitN(raw, " ", CommandPartsNumber)
@@ -66,7 +66,7 @@ func Factory(raw string, macro *Macro) (Executer, error) {
 		return NewEdit(content), nil
 	case "send":
 		if len(parts) == 1 {
-			return nil, fmt.Errorf("empty request")
+			return nil, &ErrEmptyRequest{}
 		}
 
 		return NewSend(parts[1]), nil
@@ -76,7 +76,7 @@ func Factory(raw string, macro *Macro) (Executer, error) {
 		if len(parts) > 1 {
 			sec, err := strconv.Atoi(parts[1])
 			if err != nil || sec < 0 {
-				return nil, fmt.Errorf("invalid timeout: %s", err)
+				return nil, &ErrInvalidTimeout{parts[1]}
 			}
 
 			timeout = time.Duration(sec) * time.Second
@@ -88,7 +88,7 @@ func Factory(raw string, macro *Macro) (Executer, error) {
 			return macro.Get(cmd)
 		}
 
-		return nil, fmt.Errorf("unknown command: %s", cmd)
+		return nil, &ErrUnknownCommand{cmd}
 	}
 }
 
@@ -131,7 +131,7 @@ func NewSend(request string) *Send {
 func (c *Send) Execute(exCtx ExecutionContext) (Executer, error) {
 	msg, err := exCtx.Connection().Send(c.request)
 	if err != nil {
-		return nil, fmt.Errorf("fail to send request: %s", err)
+		return nil, err
 	}
 
 	return NewPrintMsg(*msg), nil
@@ -153,16 +153,16 @@ func (c *PrintMsg) Execute(exCtx ExecutionContext) (Executer, error) {
 	output, err := exCtx.Formater().FormatMessage(msg)
 
 	if err != nil {
-		return nil, fmt.Errorf("fail to format for output file: %s, data: %q", err, msg.Data)
+		return nil, err
 	}
 
 	switch msg.Type {
 	case ws.Request:
-		color.New(color.FgGreen).Fprint(exCtx.Output(), "->\n")
+		color.New(color.FgGreen).Fprintln(exCtx.Output(), "->")
 	case ws.Response:
-		color.New(color.FgRed).Fprint(exCtx.Output(), "<-\n")
+		color.New(color.FgRed).Fprintln(exCtx.Output(), "<-")
 	default:
-		return nil, fmt.Errorf("unknown message type: %s, data: %q", msg.Type, msg.Data)
+		return nil, &ErrUnsupportedMessageType{msg.Type.String()}
 	}
 
 	fmt.Fprintf(exCtx.Output(), "%s\n", output)
@@ -170,10 +170,13 @@ func (c *PrintMsg) Execute(exCtx ExecutionContext) (Executer, error) {
 	if exCtx.OutputFile() != nil {
 		output, err := exCtx.Formater().FormatForFile(msg)
 		if err != nil {
-			return nil, fmt.Errorf("fail to write to output file: %s", err)
+			return nil, err
 		}
 
-		fmt.Fprintln(exCtx.OutputFile(), output)
+		_, err = fmt.Fprintln(exCtx.OutputFile(), output)
+		if err != nil {
+			return nil, err
+		}
 	}
 
 	return nil, nil
@@ -207,7 +210,7 @@ func (c *WaitForResp) Execute(exCtx ExecutionContext) (Executer, error) {
 	if c.timeout.Seconds() == 0 {
 		msg, ok := <-exCtx.Connection().Messages()
 		if !ok {
-			return nil, fmt.Errorf("connection closed")
+			return nil, &ErrConnectionClosed{}
 		}
 
 		return NewPrintMsg(msg), nil
@@ -215,10 +218,10 @@ func (c *WaitForResp) Execute(exCtx ExecutionContext) (Executer, error) {
 
 	select {
 	case <-time.After(c.timeout):
-		return nil, fmt.Errorf("timeout")
+		return nil, &ErrTimeout{}
 	case msg, ok := <-exCtx.Connection().Messages():
 		if !ok {
-			return nil, fmt.Errorf("connection closed")
+			return nil, &ErrConnectionClosed{}
 		}
 
 		return NewPrintMsg(msg), nil
diff --git a/pkg/command/macro.go b/pkg/command/macro.go
index 1ff7668..cade9c2 100644
--- a/pkg/command/macro.go
+++ b/pkg/command/macro.go
@@ -37,7 +37,7 @@ func NewMacro(domains []string) *Macro {
 // Otherwise, it creates a new Sequence with the commands and adds it to the macro.
 func (m *Macro) AddCommands(name string, rawCommands []string) error {
 	if _, ok := m.macro[name]; ok {
-		return fmt.Errorf("macro already exists: %s", name)
+		return &ErrDuplicateMacro{name}
 	}
 
 	commands := []Executer{}
@@ -53,7 +53,7 @@ func (m *Macro) AddCommands(name string, rawCommands []string) error {
 
 	switch len(commands) {
 	case 0:
-		return fmt.Errorf("empty macro: %s", name)
+		return ErrEmptyMacro{name}
 	case 1:
 		m.macro[name] = commands[0]
 	default:
@@ -68,7 +68,7 @@ func (m *Macro) AddCommands(name string, rawCommands []string) error {
 func (m *Macro) merge(macro *Macro) error {
 	for name, cmd := range macro.macro {
 		if _, ok := m.macro[name]; ok {
-			return fmt.Errorf("duplicate macro name: %s", name)
+			return &ErrDuplicateMacro{name}
 		}
 
 		m.macro[name] = cmd
@@ -83,7 +83,7 @@ func (m *Macro) Get(name string) (Executer, error) {
 		return cmd, nil
 	}
 
-	return nil, fmt.Errorf("unknown command: %s", name)
+	return nil, &ErrUnknownCommand{name}
 }
 
 func (m *Macro) GetNames() []string {
@@ -110,7 +110,7 @@ func LoadFromFile(path string) (*Macro, error) {
 	}
 
 	if cfg.Version != "1" {
-		return nil, fmt.Errorf("unsupported macro file version: %s", path)
+		return nil, &ErrUnsupportedVersion{cfg.Version}
 	}
 
 	macroCfg := NewMacro(cfg.Domains)
@@ -137,7 +137,6 @@ func LoadMacroForDomain(macroDir, domain string) (*Macro, error) {
 
 	for _, file := range files {
 		if file.IsDir() || (!strings.HasSuffix(file.Name(), ".yaml") && !strings.HasSuffix(file.Name(), ".yml")) {
-			fmt.Println("skip file", file.Name())
 			continue
 		}
 
diff --git a/pkg/command/macro_test.go b/pkg/command/macro_test.go
index 40e6ded..4caf4d3 100644
--- a/pkg/command/macro_test.go
+++ b/pkg/command/macro_test.go
@@ -363,8 +363,8 @@ macro:
 		t.Fatalf("LoadFromFile() error = %v, want non-nil", err)
 	}
 
-	if err.Error() != "unsupported macro file version: "+tempFile.Name() {
-		t.Errorf("LoadFromFile() error = %v, want %v", err.Error(), "unsupported macro file version: "+tempFile.Name())
+	if err.Error() != (&ErrUnsupportedVersion{"2"}).Error() {
+		t.Errorf("LoadFromFile() error = %v, want %v", err.Error(), &ErrUnsupportedVersion{"2"})
 	}
 }