add dijkstra backup script

dijkstra/.local/libexec/cron/backup

@@ -0,0 +1,79 @@
+#!/bin/sh
+
+backup_key="${HOME}/.ssh/backup"
+prune_key="${HOME}/.ssh/prune"
+backup_host="luca@server155.tralios.de"
+# shellcheck disable=SC2088
+repo="~/backup/dijkstra"
+# shellcheck disable=SC2155
+export BORG_PASSPHRASE="$(cat "${HOME}"/.secrets/borg)"
+export BORG_REPO="ssh://${backup_host}:22/${repo}"
+export BORG_RSH="ssh -i ${backup_key}"
+
+echo >"${XDG_DATA_HOME}/backup.log"
+exec >>"${XDG_DATA_HOME}/backup.log" 2>&1
+
+max() {
+	printf "%s\n" "$@" | sort -nr | head -n1
+}
+
+info() {
+	[ "$1" = "-e" ] && {
+		shift
+		notify-send -u critical Backupper "$*"
+	}
+	printf "\n%s %s\n\n" "$(date)" "$*"
+}
+trap 'echo $(date) Backup interrupted >&2; exit 2' INT TERM
+
+info "Starting backup"
+
+borg create \
+	--verbose \
+	--filter AME \
+	--list \
+	--stats \
+	--show-rc \
+	--compression lz4 \
+	--exclude-caches \
+	--exclude "${XDG_CACHE_HOME}/*" \
+	--exclude "${XDG_STATE_HOME}/*" \
+	--exclude "${XDG_CONFIG_HOME}/borg/*" \
+	--exclude "${XDG_CONFIG_HOME}/chromium/*" \
+	--exclude "${XDG_DATA_HOME}/Trash/*" \
+	--exclude "${XDG_DATA_HOME}/zsh/history" \
+	--exclude "${XDG_DATA_HOME}/backup.log" \
+	--exclude "${HOME}/.secrets/*" \
+	--exclude "${HOME}/.mozilla/firefox/*" \
+	--exclude "${HOME}/.thunderbird/*" \
+	::'{hostname}-{now}' \
+	"${HOME}"
+
+backup_exit=$?
+
+info "Pruning repository"
+
+# shellcheck disable=SC2029
+echo "${BORG_PASSPHRASE}" | ssh \
+	-o "IdentitiesOnly=yes" \
+	-i "${prune_key}" \
+	"${backup_host}" \
+	false # This command is ignored but must be set
+
+prune_exit=$?
+
+info "Compacting repository"
+
+borg compact
+
+compact_exit=$?
+
+global_exit=$(max $backup_exit $prune_exit $compact_exit)
+
+case ${global_exit} in
+	0) info "Backup, Prune, and Compact finished successfully" ;;
+	1) info -e "Backup, Prune, and/or Compact finished with warnings" ;;
+	*) info -e "Backup, Prune, and/or Compact finished with errors" ;;
+esac
+
+exit "${global_exit}"