introduce --debug flag to hide excessive error messages by default but allow displaying them

cmd/root.go

@@ -58,6 +58,7 @@ var defaultRDirs = []string{
 var defaultDirs = []string{}
 var triggerInterval int
 var colored bool
+var debug bool
 
 func init() {
 	rootCmd.PersistentFlags().BoolVarP(&logPS, "procevents", "p", true, "print new processes to stdout")
@@ -66,12 +67,13 @@ func init() {
 	rootCmd.PersistentFlags().StringArrayVarP(&dirs, "dirs", "d", defaultDirs, "watch these dirs")
 	rootCmd.PersistentFlags().IntVarP(&triggerInterval, "interval", "i", 100, "scan every 'interval' milliseconds for new processes")
 	rootCmd.PersistentFlags().BoolVarP(&colored, "color", "c", true, "color the printed events")
+	rootCmd.PersistentFlags().BoolVarP(&debug, "debug", "", false, "print detailed error messages")
 
 	log.SetOutput(os.Stdout)
 }
 
 func root(cmd *cobra.Command, args []string) {
-	logger := logging.NewLogger()
+	logger := logging.NewLogger(debug)
 
 	cfg := &config.Config{
 		RDirs:        rDirs,

internal/logging/logging.go

@@ -16,13 +16,15 @@ type Logger struct {
 	infoLogger  *log.Logger
 	errorLogger *log.Logger
 	eventLogger *log.Logger
+	debug       bool
 }
 
-func NewLogger() *Logger {
+func NewLogger(debug bool) *Logger {
 	return &Logger{
 		infoLogger:  log.New(os.Stdout, "", 0),
 		errorLogger: log.New(os.Stderr, "", 0),
 		eventLogger: log.New(os.Stdout, "", log.Ldate|log.Ltime),
+		debug:       debug,
 	}
 }
 
@@ -32,9 +34,11 @@ func (l *Logger) Infof(format string, v ...interface{}) {
 }
 
 // Errorf writes an error message to stderr
-func (l *Logger) Errorf(format string, v ...interface{}) {
+func (l *Logger) Errorf(debug bool, format string, v ...interface{}) {
+	if l.debug == debug {
 		l.errorLogger.Printf(format, v...)
 	}
+}
 
 // Eventf writes an event with timestamp to stdout
 func (l *Logger) Eventf(color int, format string, v ...interface{}) {

internal/logging/logging_test.go

@@ -13,7 +13,7 @@ const ansiPattern = "[\u001B\u009B][[\\]()#;?]*(?:(?:(?:[a-zA-Z\\d]*(?:;[a-zA-Z\
 
 var ansiMatcher = regexp.MustCompile(ansiPattern)
 
-var l = NewLogger()
+var l = NewLogger(true)
 
 var logTests = []struct {
 	logger      *log.Logger
@@ -23,8 +23,8 @@ var logTests = []struct {
 }{
 	{l.infoLogger, func() { l.Infof("Info message no. %d", 1) }, "Info message no. 1\n", nil},
 	{l.infoLogger, func() { l.Infof("Info message no. %d with a string %s\n", 2, "appended to it") }, "Info message no. 2 with a string appended to it\n", nil},
-	{l.errorLogger, func() { l.Errorf("Error message") }, "Error message\n", nil},
+	{l.errorLogger, func() { l.Errorf(true, "Error message") }, "Error message\n", nil},
-	{l.errorLogger, func() { l.Errorf("Error message\n") }, "Error message\n", nil},
+	{l.errorLogger, func() { l.Errorf(true, "Error message\n") }, "Error message\n", nil},
 	{l.eventLogger, func() { l.Eventf(ColorNone, "Event message") }, dateFormatPattern + " Event message\n", nil},
 	{l.eventLogger, func() { l.Eventf(ColorRed, "Event message") }, dateFormatPattern + " Event message\n", [][]byte{[]byte("\x1b[31;1m"), []byte("\x1b[0m")}},
 	{l.eventLogger, func() { l.Eventf(ColorGreen, "Event message") }, dateFormatPattern + " Event message\n", [][]byte{[]byte("\x1b[32;1m"), []byte("\x1b[0m")}},

internal/pspy/pspy.go

@@ -16,7 +16,7 @@ type Bindings struct {
 
 type Logger interface {
 	Infof(format string, v ...interface{})
-	Errorf(format string, v ...interface{})
+	Errorf(debug bool, format string, v ...interface{})
 	Eventf(color int, format string, v ...interface{})
 }
 
@@ -96,7 +96,7 @@ func initFSW(fsw FSWatcher, rdirs, dirs []string, logger Logger) {
 		case <-doneCh:
 			return
 		case err := <-errCh:
-			logger.Errorf("initializing fs watcher: %v", err)
+			logger.Errorf(true, "initializing fs watcher: %v", err)
 		}
 	}
 }
@@ -130,7 +130,7 @@ func triggerEvery(d time.Duration, triggerCh chan struct{}) {
 func logErrors(errCh chan error, logger Logger) {
 	for {
 		err := <-errCh
-		logger.Errorf("ERROR: %v", err)
+		logger.Errorf(true, "ERROR: %v", err)
 	}
 }
 

internal/pspy/pspy_test.go

@@ -190,6 +190,7 @@ type mockLogger struct {
 	Info  chan string
 	Error chan string
 	Event chan string
+	Debug bool
 }
 
 func newMockLogger() *mockLogger {
@@ -197,6 +198,7 @@ func newMockLogger() *mockLogger {
 		Info:  make(chan string, 10),
 		Error: make(chan string, 10),
 		Event: make(chan string, 10),
+		Debug: true,
 	}
 }
 
@@ -204,9 +206,11 @@ func (l *mockLogger) Infof(format string, v ...interface{}) {
 	l.Info <- fmt.Sprintf(format, v...)
 }
 
-func (l *mockLogger) Errorf(format string, v ...interface{}) {
+func (l *mockLogger) Errorf(debug bool, format string, v ...interface{}) {
+	if l.Debug == debug {
 		l.Error <- fmt.Sprintf(format, v...)
 	}
+}
 
 func (l *mockLogger) Eventf(color int, format string, v ...interface{}) {
 	m := fmt.Sprintf(format, v...)