A simple shell script that consistently observes a directory and synchronizes its contents when changes are found, using rsync's one-way sync.

simple-sync

#!/bin/sh

## A simple shell script that consistently observes a directory and synchronizes its contents when changes are found, using rsync's one-way sync.
## Most of the heavy lifting is really done by rsync, so what this script provides is just convenience over cron, notifications (if you have notify-pb) and rsync not being spammed by said cron job through a simple lockfile.
## simple-sync requires rsync, notify-pb (Pushbullet) and preferably run by a scheduler such as cron.

# Core variables
SYNC_HOME='/home/user'
SYNC_SOURCE='[email protected]:/path/to/source/*'
SYNC_DESTINATION="${SYNC_HOME}/path/to/destination/"

# Logging and notifications
SYNC_LOGTAG='simple-sync'
SYNC_LABEL_SOURCE='remote-machine'
SYNC_LABEL_DESTINATION='local-machine'
SYNC_TITLE="Synchronized files from ${SYNC_LABEL_SOURCE} to ${SYNC_LABEL_DESTINATION}"
SYNC_MESSAGE="New files were downloaded from ${SYNC_LABEL_SOURCE}"

# Only synchronize when the lock isn't present.
if [ ! -f "${SYNC_HOME}/.lock-sync" ]; then
	touch "${SYNC_HOME}/.lock-sync"

	# Begin syncing process. Log progress to /var/log/syslog for each step.
	logger -t ${SYNC_LOGTAG} "Downloading files from ${SYNC_LABEL_SOURCE}"
	if [ -n "$(\rsync -ai ${SYNC_SOURCE} ${SYNC_DESTINATION})" ]; then
		# If rsync -i has STDOUT results, new files were then updated so it's safe to notify via Pushbullet.
		notify-pb "${SYNC_TITLE}" "${SYNC_MESSAGE}"
		logger -t ${SYNC_LOGTAG} "${SYNC_MESSAGE}"
	else
		# Else, there weren't any changes.
		logger -t ${SYNC_LOGTAG} "No new files found."
	fi

	rm "${SYNC_HOME}/.lock-sync"
else
echo 'Process is already running. Try again later.'
fi