cron script for ubuntu servers to automatically purge old kernels, quickly insert with; curl https://gist.github.com/Thermionix/7797652/raw/purge-old-kernels | bash

purge-old-kernels

#!/bin/bash

cat <<-'EOF' | sudo tee /usr/local/sbin/purge-old-kernels
#!/bin/sh
#This script will keep the currently running kernel and 2 latest

export PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

if [ "$(id -u)" != 0 ]; then
	echo "ERROR: This script must run as root." 1>&2
	exit 1
fi

CANDIDATES=$(ls -tr /boot/vmlinuz-* | head -n -2 | grep -v "$(uname -r)$" | cut -d- -f2- | awk '{print "linux-image-" $0}')
for c in $CANDIDATES; do
	dpkg-query -s "$c" >/dev/null 2>&1 && PURGE="$PURGE $c"
done

if [ -z "$PURGE" ]; then
	echo "No kernels are eligible for removal"
	exit 0
fi

apt-get -yq remove --purge $PURGE
EOF

sudo chmod 0744 /usr/local/sbin/purge-old-kernels

echo -e "5 1 1 * * root /usr/local/sbin/purge-old-kernels > /dev/null 2>&1\n" | sudo tee /etc/cron.d/purge-old-kernels

sudo chmod 0644 /etc/cron.d/purge-old-kernels