Remove log file fallback for non-TTY output

The feature that wrote logs to a file when stdout wasn't a terminal is
removed. Systemd services already handle log persistence through journald
and its logging facilities. This duplication is unnecessary and conflicts
with standard systemd logging practices.

View log in systemd:

```
journalctl -u rttys
```

or

```
journalctl -u rttys -f
```

Signed-off-by: Jianhui Zhao <zhaojh329@gmail.com>

go.mod

@@ -15,7 +15,6 @@ require (
 	github.com/rs/zerolog v1.34.0
 	github.com/urfave/cli/v3 v3.3.8
 	github.com/valyala/bytebufferpool v1.0.0
-	golang.org/x/term v0.32.0
 )
 
 require (

go.sum

@@ -106,8 +106,6 @@ golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.12.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.33.0 h1:q3i8TbbEz+JRD9ywIRlyRAQbM0qF7hu24q3teo2hbuw=
 golang.org/x/sys v0.33.0/go.mod h1:BJP2sWEmIv4KK5OTEluFJCKSidICx8ciO85XgH3Ak8k=
-golang.org/x/term v0.32.0 h1:DR4lr0TjUs3epypdhTOkMmuF5CDFJ/8pOnbzMZPQ7bg=
-golang.org/x/term v0.32.0/go.mod h1:uZG1FhGx848Sqfsq4/DlJr3xGGsYMu/L5GW4abiaEPQ=
 golang.org/x/text v0.26.0 h1:P42AVeLghgTYr4+xUnTRKDMqpar+PtX7KWuNQL21L8M=
 golang.org/x/text v0.26.0/go.mod h1:QK15LZJUUQVJxhz7wXgxSy/CJaTFjd0G+YLonydOVQA=
 google.golang.org/protobuf v1.36.6 h1:z1NpPI8ku2WgiWnf+t9wTPsn6eP1L7ksHUlkfLvd9xY=

log/log.go

@@ -1,51 +1,15 @@
 package log
 
 import (
-	"os"
 	"path/filepath"
-	"runtime"
 	"strconv"
-	"strings"
 
 	"github.com/dwdcth/consoleEx"
 	"github.com/mattn/go-colorable"
 	"github.com/rs/zerolog"
 	"github.com/rs/zerolog/log"
-	"golang.org/x/term"
 )
 
-type logFileHook struct {
-	err  error
-	path string
-}
-
-var logFile = &logFileHook{}
-
-func (h *logFileHook) Run(e *zerolog.Event, level zerolog.Level, msg string) {
-	if h.err != nil {
-		return
-	}
-
-	f, err := os.OpenFile(h.path, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0666)
-	if err != nil {
-		h.err = err
-		log.Fatal().Msg(err.Error())
-		return
-	}
-	defer f.Close()
-
-	f.WriteString(zerolog.TimestampFunc().Format(zerolog.TimeFieldFormat) + " |")
-	f.WriteString(strings.ToUpper(level.String()) + "| ")
-
-	pc, file, line, ok := runtime.Caller(3)
-	if ok {
-		f.WriteString(zerolog.CallerMarshalFunc(pc, file, line) + " |")
-	}
-
-	f.WriteString(msg)
-	f.WriteString("\n")
-}
-
 func init() {
 	zerolog.CallerMarshalFunc = func(pc uintptr, file string, line int) string {
 		return filepath.Base(file) + ":" + strconv.Itoa(line)
@@ -54,20 +18,11 @@ func init() {
 	out := consoleEx.ConsoleWriterEx{Out: colorable.NewColorableStdout()}
 	logger := zerolog.New(out).With().Timestamp().Logger()
 
-	if !term.IsTerminal(int(os.Stdout.Fd())) {
-		logger = logger.Hook(logFile)
-	}
-
 	log.Logger = logger
 
 	zerolog.SetGlobalLevel(zerolog.InfoLevel)
 }
 
-// SetPath set the log file path
-func SetPath(path string) {
-	logFile.path = path
-}
-
 func Verbose() {
 	log.Logger = log.Logger.With().Caller().Logger()
 }

main.go

@@ -46,21 +46,11 @@ var (
 )
 
 func main() {
-	defaultLogPath := "/var/log/rttys.log"
-	if runtime.GOOS == "windows" {
-		defaultLogPath = "rttys.log"
-	}
-
 	cmd := &cli.Command{
 		Name:    "rttys",
 		Usage:   "The server side for rtty",
 		Version: RttysVersion,
 		Flags: []cli.Flag{
-			&cli.StringFlag{
-				Name:  "log",
-				Value: defaultLogPath,
-				Usage: "log file path",
-			},
 			&cli.StringFlag{
 				Name:  "log-level",
 				Value: "info",
@@ -141,8 +131,6 @@ func main() {
 func cmdAction(c context.Context, cmd *cli.Command) error {
 	defer logPanic()
 
-	xlog.SetPath(cmd.String("log"))
-
 	switch cmd.String("log-level") {
 	case "debug":
 		zerolog.SetGlobalLevel(zerolog.DebugLevel)