#!/bin/sh

# Author: Jens Giessmann jg@handcode.de
# Version: 0.1.2

# this plugin provides info about running and (last) installed kernel versions

K_NAME=''
K_RUN=''
K_INST=''

# --------------------------------------------------------------------
# FreeBSD
# --------------------------------------------------------------------
if [ "$(uname -s)" = 'FreeBSD' ]; then
    K_NAME='FreeBSD'
    K_RUN=$(sysctl -n kern.osrelease)
    K_INST=$(freebsd-version -k)
fi

# --------------------------------------------------------------------
# Debian/Ubuntu/Proxmox
# --------------------------------------------------------------------
# different kernel versions may be installed, so we need to compare
# all available versions to find the latest
dpkg_get_latest_installed () {

    # Proxmox PVE kernel package uses different naming convention. thanks @mdklapwijk
    # default debian kernel package prefix
    case "$(uname -r)" in
        *-pve)  image_prefix='pve-kernel'; image_postfix='\-pve' ;;
        *)      image_prefix='linux-image'; image_postfix='';;
    esac

    # get the version of the currently running image as start
    latest=$(dpkg -l | grep ${image_prefix}-$(uname -r) | awk '{print $3}')

    for i in $(dpkg -l | grep ${image_prefix}-$(uname -r | cut -d '.' -f1) | grep '${image_postfix}' | awk '{print $3}')
    do
        dpkg --compare-versions "${i}" gt "${latest}" && latest="${i}"
    done
    echo "${latest}"
}

if [ "$(uname -o)" = 'GNU/Linux' ]; then
    K_NAME='Linux'
    K_RUN=$(sysctl -n kernel.version | awk '{print $4}')
    K_INST=$(dpkg_get_latest_installed)
fi

# --------------------------------------------------------------------
# write plugin output if available
# --------------------------------------------------------------------
if [ -n "${K_RUN}" ]; then
    echo '<<<kernel_version_compare>>>'
    echo "${K_NAME} ${K_RUN} ${K_INST}"
fi