Asks the user whether they want to install the latest RC or stable, then downloads the correct kernel and installs it.

Ubuntu Kernel Upgrader Script

#!/bin/bash

# Ubuntu_Kernel_Upgrader_Script
# Forked from https://gist.github.com/mmstick/8493727

#set -x

rc=n # release candidate
lowlatency=n # low latency
verbose=n # be verbose


# Help

function show_help {
    echo "NAME"
    echo "    $0 - detect and download the latest available kernel in Ubuntu's repository"
    echo
    echo "SYNOPSIS"
    echo "    $0 [-r] [-l] [-c] [-h]"
    echo
    echo "DESCRIPTION"
    echo "    -r"
    echo "        look for RC (release candidate) version [default: $rc]"
    echo
    echo "    -l"
    echo "        look for low-latency version [default: $lowlatency]"
    echo
    echo "    -h"
    echo "        print this help"
    echo
    echo "AUTHOR"
    echo "     Undy / Febraury 26, 2016"
} 


# Parse command line options

OPTIND=1
while getopts "rlcvh?" opt; do
    case "$opt" in
        r)  rc=y
            ;;
        l)  lowlatency=y
            ;;
        c)  check=y
            ;;
        v)  verbose=y
            ;;
        h|\?)
            show_help
            exit 0
            ;;
    esac
done
shift $((OPTIND-1))
[ "$1" = "--" ] && shift

[ "$verbose" = "y" ] && 
      echo -e "\n rc: $rc\n low latency: $lowlatency\n check: $check\n verbose: $verbose"


# Do the job

if ! which lynx > /dev/null; then sudo apt-get install lynx -y; fi

if [ "$(getconf LONG_BIT)" == "64" ]; then arch="amd64"; else arch="i386.deb"; fi


function getfileurl() {
    local fileURL=$(lynx -dump -listonly -dont-wrap-pre -nonumbers $kernelURL | grep "$1" | grep "$2" | grep $arch.deb | cut -d ' ' -f 4 | sort -u)
    echo $fileURL
}


function getfileurlshared() {
    local fileURL=$(lynx -dump -listonly -dont-wrap-pre -nonumbers $kernelURL | grep "all.deb" | cut -d ' ' -f 4 | sort -u)
    echo $fileURL
}



# Kernel URL
#read -p "Do you want the latest RC? " rc
case "$rc" in
   y* | Y* | s* | S*) kernelURL=$(lynx -dump -nonumbers http://kernel.ubuntu.com/~kernel-ppa/mainline/ | tail -1) ;;
   n* | N*)           kernelURL=$(lynx -dump -nonumbers http://kernel.ubuntu.com/~kernel-ppa/mainline/ | grep -v rc[[:digit:]] | grep v[[:digit:]] | sort | tail -1) ;;
   *) exit ;;
esac
 
#read -p "Do you want the lowlatency kernel? " lowlatency
case "$lowlatency" in
   y* | Y* | s* | S*) kerneltype=lowlatency ;;
   n* | n*)           kerneltype=generic ;;
   *) exit ;;
esac


# Get file URLs
echo ""
echo "Getting URLs of the latest "$kerneltype" kernel..."
filename_header=$(getfileurl $kerneltype header)
filename_image=$(getfileurl $kerneltype image)
filename_shared=$(getfileurlshared)

echo "...file to download: "$filename_header
echo "...file to download: "$filename_image
echo "...file to download: "$filename_shared

echo ""
read -p "Do you want to download the files now? " yesno
case "$yesno" in
    y* | Y*) 
        wget $filename_header
        wget $filename_image
        wget $filename_shared
        echo "" ;;
    n* | n*) 
        echo "" ;;
   *) exit ;;
esac


read -p "Do you want to install this kernel now? " yesno
case "$yesno" in
   y* | Y*)
        echo "...Installing Linux Kernel"
        sudo dpkg -i linux*.deb
        echo "...Done. You may now reboot." ;;
   n* | n*) 
        echo "Goodbye." ;;
   *) exit ;;
esac

This version is great! Thank you for publishing.

Thanks @mentrelli - This version is much better, but I had to tweak it slightly to intelligently handle kernel sorting so v4.12.10 is higher than v4.9.9. See my fork, which seems to do this better