Converting this to a gist and blowing away the repo. Never been used, probably never will be.

incremental-backup.sh

#!/bin/bash
# Inspired by http://www.mikerubel.org/computers/rsync_snapshots/ 

# Command Line Options
PREFIX=$1
COUNT=$2
SOURCE_DIRECTORY=$3
DESTINATION_DIRECTORY=$4
EXCLUDES=$5

# Run checks
if [ $# -lt 4 ]
then
    echo ""
    echo "  Usage: $0 prefix count source-directory destination-directory [rsync-exclusions-file]"
    echo "  For example: $0 hourly 24 /home/user /var/backup/home/user/hourly"
    echo ""
    exit 1
elif [ ! -d $SOURCE_DIRECTORY ]
then
    echo "$SOURCE_DIRECTORY (source directory) does not exist."
    exit 2
elif [ ! -d $DESTINATION_DIRECTORY ]
then
    echo "$DESTINATION_DIRECTORY (destination directory) does not exist."
    exit 3
fi

# Delete the oldest snapshot
if [ -d $DESTINATION_DIRECTORY/$PREFIX.$COUNT ]
then
    echo "Removing $PREFIX.$COUNT"
    rm -rf $DESTINATION_DIRECTORY/$PREFIX.$COUNT
else
    echo "Not removing $PREFIX.$COUNT because it doesn't exist."
fi

# Shift the middle snapshots(s) back by one
for ((current=$COUNT; current>2; current--))
do
    previous=$(($current-1))
    if [ -d $DESTINATION_DIRECTORY/$PREFIX.$previous ]
    then
        echo "Moving $PREFIX.$previous to $PREFIX.$current"
        mv $DESTINATION_DIRECTORY/$PREFIX.$previous $DESTINATION_DIRECTORY/$PREFIX.$current
    else
        echo "Not moving $PREFIX.$previous because it does not exist"
    fi
done

# Make a hard-link-only (except for dirs) copy of the latest snapshot
# Otherwise, make $PREFIX.1
if [ -d $DESTINATION_DIRECTORY/$PREFIX.1 ]
then
    echo "Copying (-al) $PREFIX.1 to $PREFIX.2"
    cp -al $DESTINATION_DIRECTORY/$PREFIX.1 $DESTINATION_DIRECTORY/$PREFIX.2
else
    echo "Creating $DESTINATION_DIRECTORY/$PREFIX.1"
    mkdir $DESTINATION_DIRECTORY/$PREFIX.1
fi

# Create latest snapshot
echo "Running rsync on $SOURCE_DIRECTORY to $DESTINATION_DIRECTORY/$PREFIX.1"
if [ -f $EXCLUDES ]
then
    rsync -a --delete --delete-excluded --exclude-from="$EXCLUDES" $SOURCE_DIRECTORY $DESTINATION_DIRECTORY/$PREFIX.1
else
    rsync -a --delete --delete-excluded $SOURCE_DIRECTORY $DESTINATION_DIRECTORY/$PREFIX.1
fi

# Update the mtime of current snapshot
echo "Updating date of $PREFIX.1"
touch $DESTINATION_DIRECTORY/$PREFIX.1

echo "Script complete"