GnuCash files encryption script

#!/bin/bash
# This is a script to work with an encrypted gnucash file. It asks for the
# password, decrypts the file, runs gnucash, and encrypts it back. Logs and
# backups are shredded at the end.
# Author: pluton <plutonpluton@mail.ru>
# Version: 1.0 (Sat Jan 29 2011)
# License: GNU GPL 3

CP=/bin/cp
KDIALOG=/usr/bin/kdialog
OPENSSL=/usr/bin/openssl
GNUCASH=/usr/bin/gnucash
SHRED=/bin/shred
BASENAME=/usr/bin/basename
CHMOD=/bin/chmod

FILE=~/main
FILETMP="${FILE}.tmp"
TIMEOUT=2   # seconds
TITLE=$( $BASENAME $0 )

notify() {
    [ -n "$1" ] && text="$1" || text="?"
    $KDIALOG --passivepopup "$text" --title "$TITLE" $TIMEOUT
}

[ -e "$FILE" ] || { notify "File '$FILE' was not found"; exit 1; }

pass=$( $KDIALOG --password "Enter the password /GC/" )
[ "$pass" == "" ] && { notify "The password is empty"; exit 2; }

if ! $OPENSSL enc -d -aes-256-cbc -in "$FILE" -out "$FILETMP" -pass stdin <<EOF
${pass}
EOF
then
    notify "The password seems to be wrong"
    exit 3
fi
$CHMOD go= "$FILETMP"
$CP -f "$FILE" "${FILE}.bkp"
$GNUCASH "$FILETMP"
if ! $OPENSSL enc -e -aes-256-cbc -in "$FILETMP" -out "$FILE" -pass stdin <<EOF
${pass}
EOF
then
    notify "An error occured while encoding (code #$?)"
    exit 4
fi
unset pass
$SHRED -zun 2 "${FILETMP}"*
notify "Done"