This is the debugged version of SPARTACUS - the Slightly PARanoid bACkUp Script. In my foolishness, I forgot to debug thoroughly and several errors escaped me in the original, anonymous gist. This is the updated version. I might open a git repo for this, if there's sufficient interest and if I can get the remaining kinks worked out.

spartacus.cfg

# backup configuration variables fot SPARTACUS #

# this is a simple shell script that will be 
# sourced by spartacus.sh in order to 
# configure certain user-set parameters,
# which are defined below.
# this file should be placed in the 
# /etc folder as /etc/spartacus.cfg, 
# so spartacus will be able to find it.

# system profile (/ assumed)
SYSTEMDISKS=()

# home profile
HOMEDISKS=()
HOMEDIR=/home/<user>

# docs profile
DOCSDISKS=()
DOCSDIR=/home/<user>/docs

# keyfile to be used to encrypt and decrypt
# backups, in addition to passphrase provided
# at creation. Note that in this case, there
# is no benefit to assigning a binary
# keyfile to a disk already encrypted with
# a simple passphrase, so the easiest 
# solution is to create a keyfile 
# that has only a single line consisting
# of your original passphrase.
SPARTACUS_KEYFILE='/usr/local/bin/backup.keyfile'

# set backup time parameters.
# TIME is the format used by the date command
# to name your snapshots with (see man date for more
# information on the format options for date). 
# INT is the interval to use to determine what the last
# backup timestamp was. Set this to either week, day, 
# or hour. This is parsed by the date command as:
#
# date +$SPARTACUS_TIME -d "1 $SPARTACUS_INT ago"
#
# to generate the needed past-timestamp.
# OLD is an optional parameter that 
# specifies how far back you wish to keep 
# snapshots based on INT. If OLD is unset 
# or otheriwse evaluates as a null string,
# then it will be ignored and spartacus will
# keep backups indefinitely until your disk 
# runs out of space. For this reason, it is
# recommended that you set it to something sensible.
#
# MAKE SURE that TIME and INT agree, otherwise
# your snapshots will get mangled.

SPARTACUS_TIME="%Y-%m-%d_%H"
SPARTACUS_INT="hour"
#SPARTACUS_OLD=""

spartacus.sh

#!/usr/bin/bash

# SPARTACUS: the Slightly PARanoid minimalisT bACUp Script
# Written by ParanoidAndroid on Sat Jan 28 14:33:43 MST 2014
#
# this script is free and open-source software under the
# terms of the GNU General Public License v3:
# https://gnu.org/licenses/gpl-3.0-standalone.html
#
# this script comes with ABSOLUTELY NO WARRANTY, 
# explicit or implied. If you break something using 
# it, it's on you.

# define functions #

function usage {
cat << EOF
usage: spartacus PROFILE

This script will create or update a lovely, hardlinked, snapshot-style backup 
tree within a LUKS-encrypted drive partition for PROFILE, leveraging
cryptsetup and the power of rsync with its --link-dest option. If the backup 
tree doesn't exist or if there is no previous backup to link to (i.e. you are 
using a new disk) then spartacus will make a full backup.

This help message can be displayed by passing 'help' as the profile name,
i.e. 'spartacus help'

EOF
}

function mksnapshot {
    mkdir -p /mnt/backup/$PROFILE\_snapshot/$SNAPSHOT_TIMESTAMP
    sync
    
    rsync --progress --human-readable --numeric-ids --inplace --verbose --archive --delete-after --hard-links --xattrs --delete --compress --exclude={/sys/*,/mnt/*,/proc/*,/dev/*,/lost+found,/media/*,/tmp/*,/opt/*,/run/*}$PROFILEDIR/* /mnt/backup/$PROFILE\_snapshot/$SNAPSHOT_TIMESTAMP/ --link-dest=/mnt/backup/$PROFILE\_snapshot/$SNAPSHOT_LAST

    sync
}

function new_backup {
    mkdir -p /mnt/backup/$PROFILE\_snapshot
    mkdir -p /mnt/backup/$PROFILE\_snapshot/$SNAPSHOT_TIMESTAMP
    sync

    rsync --progress --human-readable --numeric-ids --inplace --verbose --archive --delete-after --hard-links --xattrs --delete --compress --exclude={/sys/*,/mnt/*,/proc/*,/dev/*,/lost+found,/media/*,/tmp/*,/opt/*,/run/*} $PROFILEDIR/* /mnt/backup/$PROFILE\_snapshot/$SNAPSHOT_TIMESTAMP/

    sync
}

function cleanup {
    # check to see if SNAPSHOT_OLD variable is set
    # if so, delete the snapshot it describes, if it exists.

    if [ ! -z $SNAPSHOT_OLD ]; then
        if [ -d /mnt/backup/$PROFILE\_snapshot/$SNAPSHOT_OLD ]; then
            rmdir /mnt/backup/$PROFILE\_snapshot/$SNAPSHOT_OLD
        else
            echo -e "snapshot $SNAPSHOT_OLD for $PROFILE does \n\
            not exist!\nskipping cleanup routine..."

        fi
    else
        echo -e "no cleanup necessary ($SPARTACUS_OLD\
        not set)."
    fi
}

function backup_profile {
    for disk in "${USEDISKS[@]}"
    do
        :            
        if [ -e $disk ]; then
            cryptsetup luksOpen $disk backup --key-file=$KEYFILE
            mount /dev/mapper/backup /mnt/backup

            if [ -d /mnt/backup/$PROFILE\_snapshot/$SNAPSHOT_LAST ]; then
                mksnapshot

            elif [ -d /mnt/backup/$PROFILE\_snapshot/$SNAPSHOT_TIMESTAMP ]; then
                echo -e "snapshot for $SNAPSHOT_TIMESTAMP already exists.\n\n\
                this script is designed to make backups once per hour, as\n\
                per the needs of the author, and will abort if attempts are \n\
                made to back up a profile multiple times in the same hour.\n\n\
                you can make it work down to the minute or second\n\
                with a few simple edits to the SNAPSHOT_TIMESTAMP, \n\
                SNAPSHOT_OLD, and SNAPSHOT_LAST environment variables, but hourly \n\
                or daily should serve as a sane default for most home users."

            else
                echo -e "no previous snapshots found.\n\
                Creating new backup..."
                
                new_backup
            fi
            
            cleanup
            umount /dev/mapper/backup
            cryptsetup luksClose /dev/mapper/backup
        else
            echo "disk $disk not online. Skipping..."
        fi
    done
}

########## main ##########
# Make sure the script is running as root
if [[ $EUID -ne 0 ]]; then
    usage
    echo "This script must be run as root" 1>&2
    exit 1
fi

# parse argument
if [ "$1" == "help" ]; then
    usage

else
    PROFILE=$1

fi

# parse the SPARTACUS configuration variables
# from /etc/spartacus.cfg

. /etc/spartacus.cfg

SNAPSHOT_TIMESTAMP=$(date +$SPARTACUS_TIME)
SNAPSHOT_LAST=$(date +$SPARTACUS_TIME -d "1 $SPARTACUS_INT ago")
SNAPSHOT_OLD=$(date +$SPARTACUS_TIME -d "$SPARTACUS_OLD $SPARTACUS_INT ago")
KEYFILE=$SPARTACUS_KEYFILE

# check to make sure variables are set
if [ -z $SPARTACUS_INT ]; then
    echo "ERROR: config variable $SPARTACUS_INT unset!"
    exit 1

elif [ -z $SPARTACUS_TIME ]; then
    echo "ERROR: config variable $SPARTACUS_TIME unset!"
    exit 1

elif [ -z $SPARTACUS_KEYFILE ]; then
    echo "ERROR: config variable $SPARTACUS_KEYFILE unset!"
    exit 1

else
    echo "configuration file /etc/spartacus.cfg parsed correctly."
fi

# create mountpoint, if it doesn't exist.
# chown it to root and chmod 0744 as cautionary measure
mkdir -p /mnt/backup
chown root /mnt/backup
chmod 0744 /mnt/backup

if [ -z $PROFILE ]; then
    usage
    echo -e "no profile specified.\
    \nUse the -p flag to specify a profile.
    \n\nmust be one of:\n\tall\
    \n\tsystem\n\thome\n\tdocs"
    exit

else
    if [ $PROFILE == "system" ]; then
        unset PROFILEDIR
        USEDISKS=$SYSTEMDISKS
        backup_profile
        echo -e "\nbackup complete"
        exit
    elif [ $PROFILE == "home" ]; then
        PROFILEDIR=$HOMEDIR
        USEDISKS=$HOMEDISKS
        backup_profile
        echo -e "\nbackup complete."
        exit
    elif [ $PROFILE == "docs" ]; then
        PROFILEDIR=$DOCSDIR
        USEDISKS=$HOMEDISKS
        backup_profile
        echo -e "\nbackup complete."
        exit
    else
        echo "ERROR: invalid profile."
        exit
    fi
fi

spartacus_mkdest.sh

#!/usr/bin/bash

# Make sure the script is running as root
if [[ $EUID -ne 0 ]]; then
    echo "This script must be run as root" 1>&2
    exit 1
fi

# source the /etc/spartacus config file
. /etc/spartacus.cfg

cryptsetup luksFormat -v -s 512 -y -h sha512 -c aes-xts-plain64 $1 && \
cryptsetup luksOpen $1 nbackup && \
mkfs.ext4 /dev/mapper/nbackup && \
cryptsetup luksClose /dev/mapper/nbackup

# check for an optional keyfile:
if [ -z $SPARTACUS_KEYFILE ]; then
    echo -e "no keyfile specified for backups.\n\
    skipping adding keyfile..."
    
elif [ ! -z $SPARTACUS_KEYFILE ]; then
    cryptsetup luksAddKey $1 $SPARTACUS_KEYFILE
fi

echo 'add the following in double quotes to the \
appropriate array in /etc/spartacus.cfg:'
echo "/dev/disk/by-uuid/$(blkid $1 | sed -n 's/.* UUID=\"\([^\"]*\)\".*/\1/p')"