Timelapse daemon for RaspberryPI

timelapsed

#!/bin/sh
### BEGIN INIT INFO
# Provides:		webcam
# Required-Start:	$remote_fs $syslog
# Required-Stop:	$remote_fs $syslog
# Default-Start:	2 3 4 5
# Default-Stop:		0 1 6
# Short-Description:	Control raspistill
# Description:		Control raspistill camera time lapse
#			and save images to RAM disk. 
#			Source: http://www.dronkert.net/rpi/webcam.html
### END INIT INFO

BIN="raspistill"
EXE="/usr/bin/$BIN"
[ -x "$EXE" ] || exit 0

SCR="timelapsed"   # script / service name
# -ts paramater replaces the frame number with timestamp value when creating file
ARG="-n -t 0 -tl 5000 -ts -o /run/shm/tl%010d.jpg"
LCK="/var/run/$SCR.pid"   # lock file location

update_lockfile() {
	PID=$(pgrep "$BIN")
	if [ -z "$PID" ]; then
		[ -f "$LCK" ] && [ -w "$LCK" ] && rm -f "$LCK"
	else
		[ -e "$LCK" ] || touch "$LCK"
		[ -f "$LCK" ] && [ -w "$LCK" ] && echo "$PID" > "$LCK"
	fi
}

do_start() {
	$EXE $ARG &
	update_lockfile
}

do_stop() {
	killall -q "$BIN"
	update_lockfile
}

case "$1" in
	status)
		echo -n "Service $SCR is "
		update_lockfile
		if [ -z "$PID" ]; then
			echo "not running." >&2
			exit 3
		else
			echo "running."
		fi
		;;
	start)
		echo -n "Starting service $SCR..."
		update_lockfile
		if [ -n "$PID" ]; then
			echo "already started." >&2
			exit 4
		else
			do_start
			echo "done."
		fi
		;;
	stop)
		echo -n "Stopping service $SCR..."
		update_lockfile
		if [ -z "$PID" ]; then
			echo "already stopped." >&2
			exit 5
		else
			do_stop
			echo "done."
		fi
		;;
	restart|force-reload)
		echo -n "Restarting service $SCR..."
		do_stop
		if [ -n "$PID" ]; then
			echo "failed to stop." >&2
			exit 6
		else
			do_start
			if [ -z "$PID" ]; then
				echo "failed to start." >&2
				exit 7
			else
				echo "done."
			fi
		fi
		;;
	*)
		echo "Usage: $0 {status|start|stop|restart|force-reload}" >&2
		exit 8
		;;
esac
exit 0