display: don't display menu if the output is non-tty
diff --git a/display.c b/display.c
index 1d3f287..3d52dff 100644
--- a/display.c
+++ b/display.c
@@ -52,9 +52,8 @@
 {
     va_list args;
     va_start(args, fmt);
-    vfprintf(stdout, fmt, args);
+    vdprintf(logFd(), fmt, args);
     va_end(args);
-    fflush(stdout);
 }
 
 static void display_printKMG(uint64_t val)
@@ -262,5 +261,8 @@
 
 extern void display_display(honggfuzz_t * hfuzz)
 {
+    if (logIsTTY() == false) {
+        return;
+    }
     display_displayLocked(hfuzz);
 }
diff --git a/log.c b/log.c
index 55f765e..17cf4ba 100644
--- a/log.c
+++ b/log.c
@@ -166,3 +166,13 @@
 {
     return &log_mutex;
 }
+
+bool logIsTTY(void)
+{
+    return log_fd_isatty;
+}
+
+int logFd(void)
+{
+    return log_fd;
+}
diff --git a/log.h b/log.h
index 0c24565..9875e07 100644
--- a/log.h
+++ b/log.h
@@ -62,6 +62,10 @@
 
 extern void logStop(int sig);
 
+extern bool logIsTTY(void);
+
+extern int logFd(void);
+
 extern pthread_mutex_t *logMutexGet(void);
 
 #endif                          /* _HF_LOG_H_ */