Make cron run twice a day, randomly

Run cron twice a day to make sure certificates are guaranteed to be renewed
at least once during the last 24 hours of the certificate lifetime.

acme.sh

@@ -4420,17 +4420,17 @@ installcronjob() {
     fi
     _t=$(_time)
     random_minute=$(_math $_t % 60)
+    random_hour1=$(_math $_t / 60 % 12)
+    random_hour2=$(_math $random_hour1 + 12)
     if _exists uname && uname -a | grep SunOS >/dev/null; then
-      crontab -l | {
-        cat
-        echo "$random_minute 0 * * * $lesh --cron --home \"$LE_WORKING_DIR\" $_c_entry> /dev/null"
-      } | crontab --
+      ct_stdin=--
     else
+      ct_stdin=-
+    fi
     crontab -l | {
       cat
-        echo "$random_minute 0 * * * $lesh --cron --home \"$LE_WORKING_DIR\" $_c_entry> /dev/null"
-      } | crontab -
-    fi
+      echo "$random_minute $random_hour1,$random_hour2 * * * $lesh --cron --home \"$LE_WORKING_DIR\" $_c_entry> /dev/null"
+    } | crontab $ct_stdin
   fi
   if [ "$?" != "0" ]; then
     _err "Install cron job failed. You need to manually renew your certs."