A quick-and-dirty patch that forces Nmap to keep printing the current progress, displaying it in a single line.

nmap-printprogress.diff

diff --git a/scan_engine.cc b/scan_engine.cc
index c712d72..e31df95 100644
--- a/scan_engine.cc
+++ b/scan_engine.cc
@@ -5738,7 +5738,7 @@ void ultra_scan(std::vector<Target *> &Targets, struct scan_lists *ports,
     // printf("TRACE: Finished waitForResponses() at %.4fs\n", o.TimeSinceStartMS(&USI.now) / 1000.0);
     processData(&USI);
 
-    if (keyWasPressed()) {
+    if (true) {
       // This prints something like
       // SYN Stealth Scan Timing: About 1.14% done; ETC: 15:01 (0:43:23 remaining);
       USI.SPM->printStats(USI.getCompletionFraction(), NULL);
diff --git a/timing.cc b/timing.cc
index 25b37eb..556ae0b 100644
--- a/timing.cc
+++ b/timing.cc
@@ -659,7 +659,7 @@ bool ScanProgressMeter::printStats(double perc_done,
   // data for decent timing estimates. Also with perc_done == 0
   // these elements will be nonsensical.
   if (perc_done < 0.01) {
-    log_write(LOG_STDOUT, "%s Timing: About %.2f%% done\n",
+    log_write(LOG_STDOUT, "\r%s Timing: About %.2f%% done",
         scantypestr, perc_done * 100);
     log_flush(LOG_STDOUT);
     return true;
@@ -676,7 +676,7 @@ bool ScanProgressMeter::printStats(double perc_done,
   ltime = localtime(&timet);
   assert(ltime);
 
-  log_write(LOG_STDOUT, "%s Timing: About %.2f%% done; ETC: %02d:%02d (%.f:%02.f:%02.f remaining)\n",
+  log_write(LOG_STDOUT, "\r%s Timing: About %.2f%% done; ETC: %02d:%02d (%.f:%02.f:%02.f remaining)",
       scantypestr, perc_done * 100, ltime->tm_hour, ltime->tm_min,
       floor(time_left_s / 60.0 / 60.0),
       floor(fmod(time_left_s / 60.0, 60.0)),