[WordPress] How to update a post during the save hook without getting stuck in an infinite loop.

1-update-post-avoid-loop.php

<?php

add_action( 'save_post', 'acme_update_post' );
/**
 * An example for how to update the title of the post during the 
 * save_post action in order to prevent infinite loops from
 * occurring.
 * 
 * @param    int    $post_id    The ID of the post that's being updated
 */
function acme_update_post( $post_id ) {

	// First we read the title and encode it
	$title = get_the_title( $post_id );

	// Next, we look to see if a certain word is present in the title
	if ( 0 < strpos( $title, "Rick Roll" ) ) {

		// We unhook this action to prevent an infinite loop
		remove_action( 'save_post', 'acme_update_post' );

		// Update the title so that it doesn't include Rick Roll
		$title = str_ireplace( "Rick Roll", "", $title );
		$args = array(
			'ID'              => $post_id,
			'post_title'      => $title
		);
		wp_update_post( $args );

		// Now hook the action
		add_action( 'save_post', 'acme_update_post' );

	}

}