Solve piholeLogFlush.sh having to be issued 2 x to clear logs (#1460)

Simplified the command -v syntax, and added a sleep 3 timer to the first execution of the log rotation. The second execution was being issued while the first was still running, thus it would fail and you would have to issue the "Flush Logs" command a second time.

advanced/Scripts/piholeLogFlush.sh

@@ -10,9 +10,9 @@
 
 echo -n "::: Flushing /var/log/pihole.log ..."
 # Test if logrotate is available on this system
-if command -v /usr/sbin/logrotate &> /dev/null; then
+if command -v /usr/sbin/logrotate >/dev/null; then
   # Flush twice to move all data out of sight of FTL
-  /usr/sbin/logrotate --force /etc/pihole/logrotate
+  /usr/sbin/logrotate --force /etc/pihole/logrotate; sleep 3
   /usr/sbin/logrotate --force /etc/pihole/logrotate
 else
   # Flush both pihole.log and pihole.log.1 (if existing)