extract a shortcode parameter from a shortcode

shortcode.php

<?php
	// Get some post. 	
	$post = get_post( 1 );

	// Get the shortcode param from a shortcode named [my-shortcode] inside the post content.
	preg_match( '/\[my-shortcode param="([a-zA-Z0-9]+)"\]/', $post->post_content, $matches );

	if ( array_key_exists( 1, $matches ) ) {
		$hash = $matches[1];
	}