I am trying to control my arduino 4-relay module thru bluetooth hc-06. I already did it by Tasker and plugins but it very slow and buggy.
All I need is bunch of commands in shell, doing connect to serial bt and sending chars.
May be python script ?
I'm currently using an app called Bluetooth Terminal for this, and I can say that it works very well!
You basically get a simple Serial monitor, and you can select the Bluetooth device you want to connect to. A screenshot of the app on my phone:

You can set whether you want a secure connection and the app also allows you to view the received/transmitted data in hex form.