usb_backup

#!/bin/bash 
#
# Script to create backups on an encrypted usb pendrive using rsnapshot
# without requiring root privilieges.
#
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# 
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
# 
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.


# Name of the encrypted partition (LUKS)
LBL=NAME

# location of the key-file
KEY=/PATH/TO/KEY/FILE

# Location of rsnapshot root
LOC=/tmp/usb_backup

# tmp file
TMP=/tmp/usb_backup_tmp


# function to wait until user presses a key
function wait_exit {
    printf "\nPress any key to continue.\n"
    read -n 1 -s -r 
    exit
}


printf "\
====================================\n\
====================================\n\
============ USB backup ============\n\
====================================\n\
====================================\n\
\n\n"



# Unlock and mount the usb drive
##############################################################################


while [[ -e $TMP ]] ; do
    read -p "$TMP already exists, please enter some characters:" IN
    TMP="$TMP$IN"
done


# Test wether the USB drive exists

if [[ -b "/dev/disk/by-label/$LBL" ]] ; then

    DRV="/dev/disk/by-label/$LBL"
else 

    if [[ -b "/dev/disk/by-partlabel/$LBL" ]] ; then

	DRV="/dev/disk/by-partlabel/$LBL"
    else

	echo "$LBL was not found. Aborted backup."
	wait_exit
    fi
fi


# Test if LUKS or already unlocked using the output from
# udisksctl info -b $DRV
`udisksctl info -b $DRV >> $TMP`


# Test if LBL is a LUKS-device
if [[ `grep -c crypto_LUKS $TMP` -eq 0 ]] ; then

    echo "No LUKS devise. Aborted."
    wait_exit
else

    DEV=`grep 'CleartextDevice:' $TMP | sed 's/.*:\s*\(.*\)/\1/'`
fi

echo "Unlocking $LBL ..."
# Unlock LBL if it is not already unlocked
if [[ $DEV == "'/'" ]] ; then

    RAW=`udisksctl unlock -b $DRV --key-file=$KEY`
    TEST=$?
    DEV=`echo $RAW | sed 's/.*\/dev\/.*\(\/dev\/.*\)\./\1/'`

    if [[ $TEST -ne 0 ]] ; then

	echo "Error while unlocking $LBL. Aborted."
	wait_exit
    else
	
	echo "Unlocked $LBL as $DEV."
    fi
else

    echo "Unlocked $LBL as $DEV."
fi


RAW=`udisksctl mount -b $DEV`
TEST=$?
MNT=`echo $RAW | sed 's/.*\(\/media.*\)\./\1/'`

#if [[ $? -eq 0 ]] ; then
#
#    MNT=`echo $RAW | sed 's/.*\(\/media.*\)\./\1/'`
#else
#    `udisksctl unmount -b $DEV >> /dev/null`
#
#    RAW=`udisksctl mount -b $DEV`
#    echo RAW: $? $RAW
#    echo $RAW
#    if [[ $? -eq 0 ]] ; then
#
#        MNT=`echo $RAW | sed 's/.*\(\/media.*\)\./\1/'`
#    else
#
#        echo "Unable to mount $LBL. Aborted."
#        wait_exit
#    fi
#    echo "Unable to mount $LBL. Aborted."
#    wait_exit
#fi

if [[ $TEST -eq 0 ]] ; then

    printf "Mounted $DEV as $MNT.\n\nStarting backup ...\n==== rsnapshot ====\n"

    # symbolic link from the actual mount location to LOC
    ln -s $MNT $LOC
    if [[ $? -eq 0 ]] ; then

        rsnapshot -c ~/.config/usb_backup backup
        printf "===================\n\n"
    else

        echo "Could not create sybolic linkt to $MNT at $LOC. Aborted"
    fi

    rm $LOC
    udisksctl unmount -b $DEV 
else

    echo "Failed to mount $LBL. Aborted."    
fi

udisksctl lock --block-device $DRV
rm $TMP
wait_exit