new try

server.py

@@ -10,19 +10,31 @@ app = Flask(__name__)
 @retry
 @app.route("/on")
 def on():
-    os.system(
-        f"gatttool -i hci0 -b b2:3b:03:00:14:d6 --char-write-req -a 0x0009 -n cc2333"
-    )
-    return "On"
+    result = subprocess.run(
+        [f"gatttool -i hci0 -b b2:3b:03:00:14:d6 --char-write-req -a 0x0009 -n cc2333"],
+        stdout=subprocess.PIPE,
+        shell=True,
+    ).stdout.decode("utf-8")
+    print(result)
+    if "Characteristic value was written successfully" not in result:
+        raise Exception
+    else:
+        return "On"
 
 
 @retry
 @app.route("/off")
 def off():
-    os.system(
-        f"gatttool -i hci0 -b b2:3b:03:00:14:d6 --char-write-req -a 0x0009 -n cc2433"
-    )
-    return "Off"
+    result = subprocess.run(
+        [f"gatttool -i hci0 -b b2:3b:03:00:14:d6 --char-write-req -a 0x0009 -n cc2433"],
+        stdout=subprocess.PIPE,
+        shell=True,
+    ).stdout.decode("utf-8")
+    print(result)
+    if "Characteristic value was written successfully" not in result:
+        raise Exception
+    else:
+        return "Off"
 
 
 @retry
@@ -44,6 +56,6 @@ def hello():
     ).stdout.decode("utf-8")
     print(result)
     if "Characteristic value was written successfully" not in result:
-        raise Exception("Didn't work")
+        raise Exception
     else:
         return request.query_string