backup-system

#!/bin/bash
#
# backup-system: Full system backup using rdiff-backup
#
# Copyright (C) 2022 Rodrigo Silva (MestreLion) <linux@rodrigosilva.com>
# License: GPLv3 or later, at your choice. See <http://www.gnu.org/licenses/gpl>
#
# Scheduling:
#   echo '@weekly root /path/to/this 2>> /var/log/backup-system.stderr.log' |
#   sudo tee /etc/cron.d/backup-system
#
# Alternatives:
#   Simple, single-dir backup:
#	source=/media/"$USER"/a
#	target=/media/"$USER"/b
#	rsync -a --info=progress2 --no-inc-recursive "${source%\/}"/ "${target%\/}"/
#   tar backup:
#	cd "$source" && sudo tar --one-file-system -cvpzf "$target"/backup.tar.xz
#   Mirror:
#	sudo rsync -axS --info=progress2 --no-inc-recursive --delete  "${source%\/}"/ "${target%\/}"/
# ------------------------------------------------------------------------------

system=$(lsb_release -sir | tr -d '.\n')
myself=${0##*/}

source=/
target=/backup/${system,,}

options=(
	--verbosity 5             # default is 3, completely silent in a normal run
	--terminal-verbosity 3    # default is --verbosity level
	--include-symbolic-links  # would be excluded by --exclude-special-files
	--exclude-special-files   # Exclude all device files, fifo files, socket files, and symbolic links.
	--exclude-other-filesystems
)

excludes=(
	'/dev/*'
	'/lost+found'
	'/media/*'      # not really needed with --exclude-other-filesystems
	'/proc/*'
	'/run/*'
	'/sys/*'
	'/tmp/*'
	'/swapfile'

	# Users' homes
	'/home/*/.local/share/Trash/*'
	'/home/*/.cache/*'
	'/home/*/.thumbnails/*'  # Not in Ubuntu 22.04+
)

# to restore /swapfile:
# sudo fallocate -l 1G /swapfile
# sudo chmod 600 /swapfile
# sudo mkswap /swapfile
# sudo swapon /swapfile

# ------------------------------------------------------------------------------

is_root() { [[ "$(id -u)" -eq 0 ]]; }
fatal()   { [[ "${1:-}" ]] && echo "$myself: error: $@" >&2 ; exit 1; }
exists()  { type "$@" >/dev/null 2>&1; }

usage() {
	if [[ "${1:-}" ]] ; then exec >&2; fi
	cat <<-USAGE
	Usage: ${myself} [SOURCE] [TARGET] [extra-rdiff-options]
	USAGE
	if [[ "${1:-}" ]] ; then
		cat <<- USAGE
		Try '$myself --help' for more information.
		USAGE
		exit 1
	fi
	cat <<-USAGE

	Backup the root filesystem using rdiff-backup

	Excludes mounts and other filesystems. Must run as root.

	SOURCE defaults to: ${source}
	TARGET defaults to: ${target}

	Default excludes:
	${excludes[@]}

	Copyright (C) 2022 Rodrigo Silva (MestreLion) <linux@rodrigosilva.com>
	License: GPLv3 or later. See <http://www.gnu.org/licenses/gpl.html>
	USAGE
	exit 0
}
for arg in "$@"; do [[ "$arg" == "-h" || "$arg" == "--help" ]] && usage; done

source=${1:-/}
target=${2:-/backup/${system,,}}
shift 2 || true

# ------------------------------------------------------------------------------

if ! is_root; then
	echo "Must run as root" >&2
	exit 1
fi

options+=( "$@" )
for exclude in "${excludes[@]}"; do
	options+=(--exclude="$exclude")
done

rdiff-backup "${options[@]}" -- "$source" "$target"