diff --git a/segment_coverage/segment_coverage/main.py b/segment_coverage/segment_coverage/main.py
index 3578ebf..b99589c 100644
--- a/segment_coverage/segment_coverage/main.py
+++ b/segment_coverage/segment_coverage/main.py
@@ -74,7 +74,7 @@ class CoverageChecker(object):
 	"""Checks the segment coverage for a given channel in a a given directoy."""
 
 	def __init__(self, channel, qualities, base_dir, first_hour, last_hour,
-			make_page, connection_string, check_interval):
+			make_page, connection_string, check_interval, output_dir, run_once):
 		"""Constructor for CoverageChecker.
 
 		Creates a checker for a given channel with specified qualities."""
@@ -87,6 +87,8 @@ class CoverageChecker(object):
 		self.make_page = make_page
 		self.db_manager = None if connection_string is None else database.DBManager(dsn=connection_string)
 		self.check_interval = check_interval
+		self.output_dir = output_dir
+		self.run_once = run_once
 		self.stopping = gevent.event.Event()
 		self.logger = logging.getLogger('CoverageChecker({})'.format(channel))
 
@@ -172,7 +174,7 @@ class CoverageChecker(object):
 		colours[coverage_mask] = matplotlib.colors.to_rgb('tab:blue')
 		colours[coverage_mask & partial_mask] = matplotlib.colors.to_rgb('tab:orange')
 		# write the pixel array to a temporary file then atomically rename it
-		path_prefix = os.path.join(self.base_dir, 'coverage-maps', '{}_{}'.format(self.channel, quality))
+		path_prefix = os.path.join(self.base_dir, self.output_dir, '{}_{}'.format(self.channel, quality))
 		temp_path = '{}_{}.png'.format(path_prefix, uuid.uuid4())
 		final_path = '{}_coverage.png'.format(path_prefix)
 		common.ensure_directory(temp_path)
@@ -232,13 +234,13 @@ class CoverageChecker(object):
 
 		for node in sorted(nodes.keys()):
 			html += """    <h3>{}</h3>
-	<img src="{}/segments/coverage-maps/{}_{}_coverage.png" alt="{}">
-""".format(node, nodes[node], self.channel, quality, node)
+	<img src="{}/segments/{}/{}_{}_coverage.png" alt="{}">
+""".format(node, nodes[node], self.output_dir, self.channel, quality, node)
 	
 		html += """  </body>
 </html>"""
 
-		path_prefix = os.path.join(self.base_dir, 'coverage-maps', '{}_{}'.format(self.channel, quality))
+		path_prefix = os.path.join(self.base_dir, self.output_dir, '{}_{}'.format(self.channel, quality))
 		temp_path = '{}_{}.html'.format(path_prefix, uuid.uuid4())
 		final_path = '{}_coverage.html'.format(path_prefix)
 		common.ensure_directory(temp_path)
@@ -534,6 +536,9 @@ class CoverageChecker(object):
 				if self.make_page:
 					self.create_coverage_page(quality)
 
+			if self.run_once:
+				break
+
 			self.stopping.wait(common.jitter(self.check_interval))
 
 
@@ -547,9 +552,11 @@ class CoverageChecker(object):
 @argh.arg('--metrics-port', help='Port for Prometheus stats. Default is 8006.')
 @argh.arg('--backdoor-port', help='Port for gevent.backdoor access. By default disabled.')
 @argh.arg('--check-interval', help='How many seconds to wait in between doing checks.')
+@argh.arg('--output-dir', help='Where to write coverage maps, relative to base dir.')
+@argh.arg('--run-once', help='Exit after completing checks once.')
 def main(channels, base_dir='.', qualities='source', first_hour=None,
 		last_hour=None, make_page=False, connection_string=None,
-		metrics_port=8006, backdoor_port=0, check_interval=300):
+		metrics_port=8006, backdoor_port=0, check_interval=300, output_dir="coverage-maps", run_once=False):
 	"""Segment coverage service"""
 
 	qualities = qualities.split(',') if qualities else []
@@ -568,7 +575,7 @@ def main(channels, base_dir='.', qualities='source', first_hour=None,
 	for channel in channels:
 		logging.info('Starting coverage checks {} with {} as qualities in {}'.format(channel, ', '.join(qualities), base_dir))
 		manager = CoverageChecker(channel, qualities, base_dir, first_hour,
-				last_hour, make_page, connection_string, check_interval)
+				last_hour, make_page, connection_string, check_interval, output_dir, run_once)
 		managers.append(manager)
 		workers.append(gevent.spawn(manager.run))
 
@@ -586,13 +593,14 @@ def main(channels, base_dir='.', qualities='source', first_hour=None,
 	# If one has stopped, either:
 	# 1. stop() was called and all are stopping
 	# 2. one errored and we should stop all remaining and report the error
-	# Our behaviour in both cases is the same:
-	# 1. Tell all managers to gracefully stop
-	stop()
-	# 2. Wait (with timeout) until they've stopped
+	# 3. We were only told to run once, and it's finished.
+	# For cases 1 & 2, tell everyone else to stop. In the run-once case, let everyone else finish naturally.
+	if not run_once:
+		stop()
+	# Then wait until they've stopped
 	gevent.wait(workers)
-	# 3. Check if any of them failed. If they did, report it. If mulitple
-	#	failed, we report one arbitrarily.
+	# Finally, check if any of them failed. If they did, report it. If mulitple
+	# failed, we report one arbitrarily.
 	for worker in workers:
 		worker.get()