Command? The “/” command? None . It has to be done with your movement joystick. Anyhow these are the commands for Sentries.
Since you’re in mobile, S S is like two swipes down, W W two swipes up, W S is swipe up then swipe down. Like that though it’ll be harder to do in mobile. You might already know this though but im just making sure.
Also, these arent the entirety of it. You can see the full guide of Zombies Abilities here in this link Zombies Abilities .