Common WordPress Functions

wp-excerpts.php

//Update length
function custom_excerpt_length( $length ) {
	return 20;
}
add_filter( 'excerpt_length', 'custom_excerpt_length', 999 );

//Update more indicator
function custom_excerpt_more( $more ) {
    return '...';
}
add_filter( 'excerpt_more', 'custom_excerpt_more' );