fifo_bridge.py: Write PID to a file

.env

@@ -9,3 +9,6 @@ SERIAL_SPEED=9600
 
 # FIFO filename
 FIFO="/tmp/mapid"
+
+# fifo_bridge.py PID file
+FIFO_BRIDGE_PID_FILE="/tmp/mapid_fifo_bridge.pid"

fifo_bridge.py

@@ -16,20 +16,32 @@ def main():
 	if len(sys.argv) == 2:
 		FIFO = sys.argv[1]
 
+	# Write PID
+	FIFO_BRIDGE_PID_FILE = os.environ.get("FIFO_BRIDGE_PID_FILE")
+	f = open(FIFO_BRIDGE_PID_FILE, "w")
+	f.write(os.getpid())
+	f.close()
+	del f
+
+	# Create MAPIDCP object to communicate with the Arduino
 	m = mapid.MAPIDCP()
 
+	# Create FIFO
 	os.mkfifo(FIFO)
 	time.sleep(0.2)
 	print("Created FIFO " + FIFO, file=sys.stderr)
 
 	f = open(FIFO, "r")
 	print("Opened FIFO for reading", file=sys.stderr)
+
+	# Show greeting on screen
 	m.cls()
 	m.line(1)
 	m.echo("fifo_bridge.py")
 	m.line(2)
 	m.echo(FIFO)
 
+	# Main loop: read commands from FIFO and execute it
 	keep_going = True
 	while keep_going:
 		try:
@@ -42,7 +54,9 @@ def main():
 			keep_going = False
 			print("Caught a SerialException. Exiting now...", file=sys.stderr)
 
+	# Remove FIFO and PID files
 	os.remove(FIFO)
+	os.remove(FIFO_BRIDGE_PID_FILE)
 	print("Removed FIFO.", file=sys.stderr)