backup: Disable status output for --quiet

internal/ui/termstatus/status.go

@@ -44,8 +44,9 @@ type fder interface {
 // a file (e.g. via shell output redirection) or is just an io.Writer (not the
 // open *os.File for stdout), no status lines are printed. The status lines and
 // normal output (via Print/Printf) are written to wr, error messages are
-// written to errWriter.
-func New(wr io.Writer, errWriter io.Writer) *Terminal {
+// written to errWriter. If disableStatus is set to true, no status messages
+// are printed even if the terminal supports it.
+func New(wr io.Writer, errWriter io.Writer, disableStatus bool) *Terminal {
 	t := &Terminal{
 		wr:        bufio.NewWriter(wr),
 		errWriter: errWriter,
@@ -54,6 +55,10 @@ func New(wr io.Writer, errWriter io.Writer) *Terminal {
 		status:    make(chan status),
 	}
 
+	if disableStatus {
+		return t
+	}
+
 	if d, ok := wr.(fder); ok && canUpdateStatus(d.Fd()) {
 		// only use the fancy status code when we're running on a real terminal.
 		t.canUpdateStatus = true