Kindle Utility: Clean orphan sdr folder which books has been removed

sdr-clean.sh

#!/bin/bash
#author: Jia Sui
#email: jsfaint@gmail.com
#Description: Clean orphan sdr folder which books has been removed.

# Check if Kindle was mounted
df -h | grep -i kindle > /dev/null
if [[ $? -ne 0 ]]; then
    echo "Kindle was not mounted"
    exit 1
fi

#Search for Kindle mount point
mpoint=`df -h | grep -i kindle | awk '{print $NF}'`

KINDLE_DOC="$mpoint/documents"
FOLDER_LIST="
$KINDLE_DOC/*
$KINDLE_DOC/dictionaries/*
"

for i in $FOLDER_LIST
do
    for TEST in $i
    do
        #Check if it is folder
        [ ! -d $TEST ] && continue

        #Check if the name end with sdr
        echo $TEST | grep "[.]sdr\$" > /dev/null
        [[ $? -ne 0 ]] && continue

        TEST2=$(ls -Al "`dirname \"$TEST\"`""/""`echo "$TEST"| sed 's|.*\/\([^\.]*\)\(\..*\)$|\1|g'`".*"" | grep -v 'sdr' | grep "`dirname \"$TEST\"`" )
        if [ -z "$TEST2" ]; then
            echo "Remove $TEST"
            rm -rf "$TEST"
        fi
    done
done