Update ubuntu_update_check.sh

 * /usr/lib/update-notifier/apt-check was not returning a count of
   upgradeable packages on various machines even though you could
   see packages available for update via `apt-get update`
 * Replace with `apt list --upgradeable` and parse out the count
   of upgradeable security and non-security package updates available

Author: tcaddy

ubuntu_updates_check.sh

@@ -23,15 +23,15 @@
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 # THE SOFTWARE.
 
-OUTPUT=$(/usr/lib/update-notifier/apt-check 2>&1)
+OUTPUT=$(apt list --upgradable 2>/dev/null)
 
 if [ $? -ne 0 ]; then
     echo "Failed to retrieve a number of pending updates"
     exit 100
 fi
 
-PENDING_OTHER=$(echo "${OUTPUT}" | cut -d ";" -f 1)
-PENDING_SECURITY=$(echo "${OUTPUT}" | cut -d ";" -f 2)
+PENDING_OTHER=$(echo "${OUTPUT}" | grep -v "Listing..." | grep -v "/$(lsb_release -cs)-security" | wc -l)
+PENDING_SECURITY=$(echo "${OUTPUT}" | grep -v "Listing..." | grep "/$(lsb_release -cs)-security" | wc -l)
 REBOOT_REQUIRED="no"
 
 if [ -f "/var/run/reboot-required" ]; then
@@ -51,4 +51,4 @@ echo "metric pending_other uint32 ${PENDING_OTHER}"
 echo "metric reboot_required string ${REBOOT_REQUIRED}"
 echo "metric upgradable_packages string ${UPGRADABLE_PACKAGES}"
 
-exit 0
+exit 0