install-fsck-service

#!/bin/sh
set -e

PWD=$(pwd)

install_systemd () {
	local dir=~/.config/systemd/user
	if SYSTEMCTL=$(which systemctl); then
		if SYSTEMD_PATH=$(which systemd-path); then
			dir=$("${SYSTEMD_PATH}" user-configuration)/systemd/user
		fi
		mkdir -p "${dir}"
		file="${dir}/iabak-cronjob"
		if [ ! -f "${file}.service" -o ! -f "${file}.timer" ]; then
			cat <<-EOF >"${file}.service"
				[Service]
				Type=simple
				WorkingDirectory=${PWD}
				ExecStart=${PWD}/iabak-cronjob
				EOF
			cat <<-EOF >"${file}.timer"
				[Timer]
				OnCalendar=*-*-* 00:00:00
				AccuracySec=6h
				Persistent=true
				[Install]
				WantedBy=default.target
				EOF
			if ! ( "${SYSTEMCTL}" --user daemon-reload && "${SYSTEMCTL}" --user enable iabak-cronjob.timer ); then
				echo "Your systemd doesn't appear to be configured to run user jobs."
				echo "Falling back to an old-school cron job."
				rm -f "${file}.service" "${file}.timer"
				return 1
			fi
			echo "Systemd service iabak-cronjob installed and enabled."
			echo "*** Note: you may need to run 'loginctl enable-linger $(whoami)' in order for this job to run while you are logged out."
		else
			echo "You've already got the iabak-cronjob service installed; I didn't need to do anything. Thanks!"
		fi
	else
		echo "Your system doesn't use systemd; falling back to an old-school cron job."
		return 1
	fi
}

install_cron () {
	if CRONTAB=$(which crontab); then
		if ! "${CRONTAB}" -l 2>&- | grep "${PWD}/iabak-cronjob" -q; then
			tmp=$(tempfile || echo install-fsck-service-tmp-$$)
			crontab -l >${tmp} 2>&- || true
			echo "02 02 * * * ${PWD}/iabak-cronjob >${PWD}/iabak-cronjob.log 2>&1" >>${tmp}
			crontab ${tmp}
			echo "Cron job installed."
		else
			echo "You've already got the cron job installed; I didn't need to do anything. Thanks!"
		fi
	else
		echo "Your system doesn't have crontab(1), this is a pretty bad sign."
		return 1
	fi
}

install_systemd || install_cron || echo "Installation failed. Please install cron and rerun install-fsck-service."