wp-functions-excerpts.php

<?php
//change the default (55 words) length of excerpts to 20 words
function new_ex_length($length) {
    return 20;
}
add_filter('excerpt_length', 'new_ex_length', 999);

//changes the [...] to a button when excerpt content is truncated
    function new_excerpt_more($more) {
       $readmore = 'Read More';
       return ' <a class="readmore" href="'. get_permalink($post-&gt;ID) . '">' . $readmore. '</a>';
    }
add_filter('excerpt_more', 'new_excerpt_more');