What is the Input Key for the Steam Vive triggers?

using UnityEngine;
using System.Collections;

public class Press_Space_to_Fire : MonoBehaviour
{
	//Drag in the Bullet Emitter from the Component Inspector.
	public GameObject Bullet_Emitter;

	//Drag in the Bullet Prefab from the Component Inspector.
	public GameObject Bullet;

	//Enter the Speed of the Bullet from the Component Inspector.
	public float Bullet_Forward_Force;

	// Use this for initialization
	void Start ()
	{

	}

	// Update is called once per frame
	void Update ()
	{
		if (Input.GetKeyDown("fire"))
		{
			//The Bullet instantiation happens here.
			GameObject Temporary_Bullet_Handler;
			Temporary_Bullet_Handler = Instantiate(Bullet,Bullet_Emitter.transform.position,Bullet_Emitter.transform.rotation) as GameObject;

			//Sometimes bullets may appear rotated incorrectly due to the way its pivot was set from the original modeling package.
			//This is EASILY corrected here, you might have to rotate it from a different axis and or angle based on your particular mesh.
			Temporary_Bullet_Handler.transform.Rotate(Vector3.left * 90);

			//Retrieve the Rigidbody component from the instantiated Bullet and control it.
			Rigidbody Temporary_RigidBody;
			Temporary_RigidBody = Temporary_Bullet_Handler.GetComponent<Rigidbody>();

			//Tell the bullet to be "pushed" forward by an amount set by Bullet_Forward_Force. 
			Temporary_RigidBody.AddForce(transform.forward * Bullet_Forward_Force);

			//Basic Clean Up, set the Bullets to self destruct after 10 Seconds, I am being VERY generous here, normally 3 seconds is plenty.
			Destroy(Temporary_Bullet_Handler, 10.0f);
		}
	}
}

There’s a table halfway down this page in the documentation which looks like it might describe what you need.

  • Left Controller Trigger: Axis 9
  • Right Controller Trigger: Axis 10

You should set up an input in Unity with these axis and use Input.GetAxis("ExampleInputName") to read the value at runtime.