#!/bin/bash


# Clean old kernel files using apt autoremove when /boot volume exceeds a defined max.
# Usage: call during privileged user session startup.
# XFCE Example:
# Session and Startup >> Application AutoStart tab >> Add button
# Name: Kernel Purge
# Description: Purge Old Kernel data from /boot if usage > 55%
# Command: /usr/bin/xfce4-terminal --geometry=130x30+800+400 -e /home/<USER>/bin/kernelpurge.sh
#
# TODO: Add arg handling to pass usage.  Use existing value 55 as default.


max_boot_usage=55

# Commands
uname=/bin/uname
echo=/bin/echo
cat=/bin/cat
df=/bin/df
egrep=/bin/egrep
tr=/usr/bin/tr
sudo=/usr/bin/sudo
apt=/usr/bin/apt
sleep=/bin/sleep


$echo "Checking /boot usage..."

busage=$($df --output=pcent /boot | $egrep '[[:digit:]]+' | $tr -d '% ')

if [[ $busage -gt $max_boot_usage ]];then
$cat << HERE
  /boot usage greater than ${max_boot_usage}%! Taking action to purge...

  Prior to purging, make sure you can boot into the current Kernel version:
    $($uname -r)

  The current Kernel version:
    $($uname -r) should NOT appear in the list of packages produced by apt autoremove

  Following entry of sudo credentials you will be prompted by apt prior to removal.
HERE
  $sudo $apt autoremove --purge
else
	$echo "/boot usage less than ${max_boot_usage}% ($busage). Skipping purge process"
fi

$sleep 3