Back up and restore Raspbery Pi microsd card

pi.sh

#!/bin/bash
#
# Usage:
#   ./pi.sh backup /dev/sdb
#   ./pi.sh restore /dev/sdb
#
# Files created and used during backup and restore: 
# mbr.img sfdisk.dump partition[12].parted
#
# For raspbian images, use minimum 8GB microsd card
#

# this var not used at the moment, we always compress
use_compression=1

# check if binary exists, if not display message and quit
exists () {
    hash $1 2> /dev/null || { echo "Command '$1' not found"; exit 1; }
    return 0
}

help () {
    echo "Usage: $0 backup /dev/sdx"
    echo "       $0 restore /dev/sdx"
    exit 0
}

# check correct number of args
(( $# == 2 )) || help

# check these binaries exist
for cmd in sfdisk partclone.fat partclone.extfs pigz; do
    exists $cmd
done

device=$2

if [ "$1" = "backup" ]; then
    echo "Making image of MBR..."
    dd bs=512 count=1 if=$device of=mbr.img
    sfdisk -d $device > sfdisk.dump  # just saving as a human readable partition table
    echo ""
    partclone.fat   -N -c -s "${device}1" | pigz -6 > partition1.parted.gz
    partclone.extfs -N -c -s "${device}2" | pigz -6 > partition2.parted.gz
    sync
fi

if [ "$1" = "restore" ]; then
    echo "Restoring image of MBR..."
    dd bs=512 count=1 if=mbr.img of=$device
    sync
    partprobe
    echo "Writing to partitions..."
    umount "${device}1" &> /dev/null
    umount "${device}2" &> /dev/null
    sleep 2
    pigz -dc partition1.parted.gz | partclone.fat   -N -r -o "${device}1"
    pigz -dc partition2.parted.gz | partclone.extfs -N -r -o "${device}2"
    sync
fi