The daily cron job does little bit more, actually.

• create gzipped tar with /etc and other named directories
• it creates list of extra installed packages from repositories
• copy backup over LAN or Internet, checks if NFS disk is mounted or remote directory exists
• it uses tar, cp and rsync commands

You can add it to cron via this commands:

touch /etc/cron.daily/backup-configuration
chown root:root /etc/cron.daily/backup-configuration
chmod 755 /etc/cron.daily/backup-configuration

/etc/cron.daily/backup-configuration

#!/bin/bash

## global variables

# change variables according to your needs

# destination remote directory to save backups
remote_directory=/disk/backup/home-desktop
# destination local NFS mount point
local_mount_point=/disk
# source local directory to store backups
local_directory=/var/backups
# destination SSH login and server name to save backups
remote_server_login=jan@faix.cz
# list of configuration directories and files you want to backup
backup_list="/etc \
             /usr/local/bin \
             /usr/local/etc \
             /var/spool/cron \
             /var/backups/*.0 \
             /var/backups/*.bak
             /var/backups/*.txt"
# parameter the script was launched with or set default LAN
if [ -z "$1" ]; then
    parameter=-LAN
  else
    parameter="$1"
fi

# do not change following variables
# local server name
machine_name=`hostname -s`

## functions
bck_cfg() {
  aptitude -F %p search "?and(?installed,?not(?automatic))" > $local_directory/pkglist.txt
  tar -czPf $local_directory/$machine_name.tar.gz $backup_list
}
start_job() { printf "\nStarting configuration backup job at `date +%c` ...\n"
}
job_complete() { printf "\nConfiguration backup job successfuly completed on host `hostname` at `date +%c`.\n"
}
dir_not() { printf "\nConfiguration backup job failed on host `hostname` at `date +%c`, $dir_loc does not exist.\n"
}

# check if local_directory does not exist, print error message and exit
if [ ! -d $local_directory ]; then
  dir_loc="local directory $local_directory"
  dir_not && exit
fi

# in case the parameter -LAN or -Internet is used, start configuration backup
case $parameter in
    -LAN)
    ## configuration backup job inside LAN
    dir_loc="local directory $local_directory"
    if [ ! -d $remote_directory ]; then
        mount $local_mount_point
    fi

    if [ -d $remote_directory ]; then
        start_job && bck_cfg
        cp $local_directory/$machine_name.tar.gz $remote_directory
        job_complete
      else
        dir_not
    fi
    ;;
    -Internet)
    ## configuration backup job over Internet
    dir_loc="remote directory $remote_directory"
    if (ssh $remote_server_login "[ ! -d $remote_directory ]"); then
        dir_not_ && exit
    fi

    if [ -d $local_directory ]; then
        start_job && bck_cfg
        rsync -azs --stats $local_directory/$machine_name.tar.gz $remote_server_login:$remote_directory/
        job_complete
      else
        dir_not
    fi
    ;;
    *)
    ## print help
    printf "\nThis script create machine configuration backup and copy it over network to destination server.\n"
    printf "\nConfiguration backup script must be run with one of the floowing parameter:\n"
    printf "\n\t-LAN\t\tbackup configuration within LAN to mounted NFS disk"
    printf "\n\t-Internet\tbackup configuration over Internet via rsync to destination folder\n"
    printf "\t\t\tDon't forget to exchange SSH keys running \"ssh-copy-id $remote_server_login\" from source machine you launch backup configuration script.\n"
    printf "\nCheck variables defined in begining of this script:\n"
    printf "\n\tremote_directory=$remote_directory"
    printf "\n\tlocal_mount_point=$local_mount_point"
    printf "\n\tlocal_directory=$local_directory"
    printf "\n\tremote_server_login=$remote_server_login"
    printf "\n\tbackup_list=$backup_list"
    printf "\n\tmachine_name=$machine_name"
    printf "\n\tdefault parameter=$parameter"
    printf "\n\n"
    ;;
esac