A Custom Check for CheckMK - Checks RHEL/Debian and derived OS's for pending reboots

needs-restarted

#!/bin/bash
# Filename: /local/share/check_mk/agents/custom/linux-reboot/lib/local/600/needs-restarted

source /etc/os-release
VERSION=$(echo ${VERSION} | awk -F . '{ print $1 }')

# RHEL and Derivatives
if ([[ $ID_LIKE =~ 'fedora' ]] || [[ $ID =~ 'rhel' ]]) && [[ $VERSION =~ '8' ]];
then
  # RHEL 8
  REBOOT=`dnf needs-restarting -r >/dev/null 2>&1; echo $?;`
elif ([[ $ID_LIKE =~ 'fedora' ]] || [[ $ID =~ 'rhel' ]]) && [[ $VERSION =~ '7' ]]
then
  # RHEL 7
  REBOOT=`needs-restarting -r >/dev/null 2>&1; echo $?;`
fi
# Debian and Derivatives
if ([[ $ID_LIKE =~ 'debian' ]] || [[ $ID =~ 'debian' ]]);
then
  # Nice and easy,  check if /var/run/reboot-required is present
  if [ -f /var/run/reboot-required ];
  then
    REBOOT=1
  else
    REBOOT=0
  fi
fi

if [[ $REBOOT -eq 0 ]]
then
  echo "0 reboot-required - OK: Reboot not required"
elif [[ $REBOOT -ge 1 ]]
then
  echo "1 reboot-required - WARN: Updated packages indicate reboot is required"
fi