Nagios Plugin to monitor number of upgradable packages

count_apt_upgradable.sh

#!/usr/bin/env bash
PACKAGES=`apt list --upgradable 2>/dev/null | wc -l`

echo "Trovati $PACKAGES package da aggiornare"

# soglie da default
WARNING=10
CRITICAL=20

# Leggo i valori delle opzioni
while [[ $# -gt 0 ]]
do
    key="$1"

    case $key in
        -w)
        WARNING="$2"
        shift # past argument
        shift # past value
        ;;
        -c)
        CRITICAL="$2"
        shift # past argument
        shift # past value
        ;;
    esac
done

if [[ $(expr PACKAGES) -ge $(expr CRITICAL) ]]; then
  echo "CRITICAL: $PACKAGES upgradable"
  exit 2
fi


if [[ $(expr PACKAGES) -ge $(expr WARNING) ]]; then
  echo "WARNING: $PACKAGES upgradable"
  exit 1
fi

echo "OK: $PACKAGES upgradable"
exit 0