Create Raspberry Pi backups using a script launched as a cronjob

raspberry-pi-backup.sh

#!/bin/bash

# Cron installation:
# 30 05 * * 0 /root/scripts/raspberry-pi-backup.sh >> /var/log/backup.log 2>&1

# Configuration
external="/mnt/backup"       # Check if external storage is mounted
folder="$external/raspi" # Base backup folder
dev="/dev/mmcblk0"       # Device to backup
days=60                  # Delete backups older than X days
min_backups=30           # Amount of minimum backups to keep

echo "--------------------------------------"

echo "Start at: `date "+%Y-%m-%d %H:%M:%S"`"

if [ "$external" != "" ]; then
    mounted=$(mount | grep $external)

    if [ "$mounted" == "" ]; then
        echo 'External Disk is not mounted'

        mount

        exit 1
    fi
fi

if [ ! -d "$folder" ]; then
    install -d "$folder"
fi

image=$folder'/'$(date "+%Y-%m-%d_%H-%M-%S")'.img.gzip'

echo "Dumping dev to $image"
echo "dd if=$dev bs=1M | gzip > $image"

dd if=$dev bs=1M | gzip > $image

echo "Check amount of backups"
echo "find $folder -maxdepth 1 -name "*.img.gzip" -type f -mtime -$days | wc -l"
current_backups=`find $folder -maxdepth 1 -name "*.img.gzip" -type f -mtime -$days | wc -l`
if [ "$current_backups" -gt "$min_backups" ]; then
	echo "More than $min_backups backups to keep found"
    echo "Deleting old images"
    echo "find $folder -maxdepth 1 -name *.img.gzip -type f -mtime +$days -exec rm -rf {} \;"
    find $folder -maxdepth 1 -name "*.img.gzip" -type f -mtime +$days -exec rm -rf {} \;
fi
echo "End at: `date "+%Y-%m-%d %H:%M:%S"`"

exit 0