Change shader property and make all materials using shader change also

Kind of hard to word, but I have a shader and I want to change the float value using another script. When I change the float value of a specific property I want all materials using the shader to change also.

How can I do this? I have looked through the documentation and found nothing.

This is as close as I have gotten, but it only fades the material assigned, not all materials using that shader. In java

snowObject.renderer.sharedMaterial.SetFloat( "_Fade", dynamicSnowFade );
Object [] renderers = GameObject.FindObjectsOfType(typeof(Renderer));
int i_max = renderers.Length;
for (int i = 0; i < i_max; i++)
	Material[] materials = ((Renderer)renderers*).materials;*
*	int j_max = materials.Length;*
*	for (int j = 0; j < j_max; j++)*
*	{*
_		if (materials* == "YOUR SHADER")*_
_*		{*_
_			materials*.SetFloat("VALUE NAME", 1.0f);*_
_*		}*_
_*	}*_