Check that temperature value is returned

src/freedombone-installer

@@ -1400,8 +1400,11 @@ function update_system_monitor {
         total_memory=$(free -m | grep "Mem:" | awk -F ' ' '{print $2}')
         used_memory_percent=$((used_memory * 100 / total_memory))
 
+        cpu_temperature=0
         cpu_temp=$(cat /sys/class/thermal/thermal_zone*/temp | head -n 1)
-        cpu_temperature=$((cpu_temp / 1000))
+        if [ "$cpu_temp" ]; then
+            cpu_temperature=$((cpu_temp / 1000))
+        fi
 
         local_hostname=$(grep 'host-name' /etc/avahi/avahi-daemon.conf | awk -F '=' '{print $2}').local
         webadmin_install_dir="/var/www/${local_hostname}/htdocs/admin"

src/freedombone-utils-webadmin

@@ -705,8 +705,11 @@ function webadmin_update_system_monitor {
     total_memory=$(free -m | grep "Mem:" | awk -F ' ' '{print $2}')
     used_memory_percent=$((used_memory * 100 / total_memory))
 
+    cpu_temperature=0
     cpu_temp=$(cat /sys/class/thermal/thermal_zone*/temp | head -n 1)
-    cpu_temperature=$((cpu_temp / 1000))
+    if [ "$cpu_temp" ]; then
+        cpu_temperature=$((cpu_temp / 1000))
+    fi
 
     local_hostname=$(grep 'host-name' /etc/avahi/avahi-daemon.conf | awk -F '=' '{print $2}').local
     webadmin_install_dir="/var/www/${local_hostname}/htdocs/admin"

webadmin/systemmonitor.php

@@ -5,7 +5,7 @@
 $output_filename = "settings.html";
 
 if (isset($_POST['submitsystemmonitor'])) {
-    $system_monitor_file = fopen(".system_monitor.txt", "w") or die("Unable to create setup file");
+    $system_monitor_file = fopen(".system_monitor.txt", "w") or die("Unable to create system monitor file");
     fwrite($system_monitor_file, " ");
     fclose($system_monitor_file);
     $output_filename = "system_monitor.html";