This simple bash script is able to backup all given files and folders to a backup destination. I use it to backup all my Raspberry Pis, Banana Pis and also my notebook to my Synology NAS.

#!/bin/bash
# Lockfilecheck for race condition protection 
exec 9>.backupLockFile
if ! flock -n 9 ; then
    echo "Another instance is already running dude!";
    exit 1;
fi
 
#echo "1: $1";
#echo "2: $2";
#echo "3: $3";
#echo "4: $4";
 
DATE=`date +%y%m%d`;
 
SOURCES="/*";
 
if [ "$1" == "help" ]
    then
    echo "Help";
    echo "- USAGE: bash backup_to_synology.sh [DIRTOBACKUP] [EXCLUDEFILEPATH] [BACKUPDESTINATION] [disable-dry-run]";
    echo "- OR: bash backup_to_synology.sh null null [BACKUPDESTINATION] [disable-dry-run]";
    echo "- OR: bash backup_to_synology.sh [DIRTOBACKUP] null [BACKUPDESTINATION] [disable-dry-run]";
    echo "- OR: bash backup_to_synology.sh [DIRTOBACKUP] null [BACKUPDESTINATION] [disable-dry-run] [logfile]";
    exit 0;
elif [ -n "$1" -a "$1" != "null" ]
    then 
    SOURCES="$1";
fi 
 
EXCLUDEFILE="";
if [ -n "$2" -a "$2" != "null" ]
    then
    EXCLUDEFILE="--exclude-from=$2";
fi
 
# Define remote target
TARGET="";
if [ -n "$3" -a "$3" != "null" ] 
    then
    TARGET="$3";
else
    echo "You have to give me a destination";
    exit 1;     
fi
 
DRYRUN="--dry-run";
if [ -n "$4" -a "$4" == "disable-dry-run" ]
    then
    DRYRUN="";
fi
# rsync base params
# --delete - delete destination files that dosn't exist on the source
# --exclude-from - file / folders to ignore can be 
#
# use -–dry-run to simulate backup -> this is the default mode unless disable-dry-run is set
PARAMS="-azvrpuE --delete";
 
# Path to logfile
LOGFILE="rsync_log.$DATE.log";
if [ -n "$5" -a "$5" != "null" ]
    then
    LOGFILE="$5";
fi

# determine the path to "rsync"
RSYNC=`which rsync`;
 
# run backup command
$RSYNC $PARAMS $DRYRUN $EXCLUDEFILE $SOURCES $TARGET > $LOGFILE;
 
exit 0;

Example call:

$> bash backup_to_synology.sh "/data/snots/*" exclude.txt backup@ds.intern.ask-sheldon.com:/volume1/NetBackup/thinkpad disable-dry-run logfile.log

If you want to run it as a crontab, you can use key based authentication (see SSH key authentication).

The script is also able to ignore defined source paths based on a exclude list. On Ubuntu for example the following  files and folders have to be excluded in a backup to be able to boot from the backup in a case of disaster recovery. That’s why they are listed in the exclude.txt:

/dev/* 
/home/*/.gvfs 
/home/*/.mozilla/firefox/*/Cache 
/home/*/.cache/chromium 
/home/*/.thumbnails 
/media/* 
/mnt/* 
/proc/* 
/sys/* 
/tmp/* 
/home/*/.local/share/Trash 
/etc/fstab 
/var/run/* 
/var/lock/* 
/lib/modules/*/volatile/.mounted 
/var/cache/apt/archives/* 
*.Trashes

Permission errors

If you got permission errors like this,

rsync: chown "/mnt/all-inkl/." failed: Permission denied (13)
rsync: failed to set times on "/mnt/all-inkl/etc/alternatives/vim": No such file or directory (2)

you probably don’t have the the rights to change the users or permissions on the target host. The errors occurs because rsync tries to assign the same users, groups, timestamps and permissions to the files and folders on the target system as they are set on the source system.

The solution is, to change the rsync-parameters like that:

PARAMS="-azvu --no-o --no-g --no-t --delete";