function hide_update_notice_to_all_but_admin_users() 
{
    if (!current_user_can('update_core')) {
        remove_action( 'admin_notices', 'update_nag', 3 );
    }
}
add_action( 'admin_notices', 'hide_update_notice_to_all_but_admin_users', 1 );

remove_filter('the_content', 'wpautop');

How to disable automatic paragraphs in WordPress editor

Change WordPress Page to Post

UPDATE wp_posts SET post_type='post' WHERE post_type='page' AND id=X

Change WordPress Categories to Tags

UPDATE wp_term_taxonomy SET taxonomy='post_tag', parent=0 WHERE taxonomy='category'

Izvor: http://migratetowp.com/wp-database-snippet-from-categories-to-tags-and-vice-versa-with-a-single-sql-update/

global $wp_query;
$total = $wp_query->max_num_pages;
// only bother with the rest if we have more than 1 page!
if ( $total > 1 )  {
     // get the current page
     if ( !$current_page = get_query_var('paged') )
          $current_page = 1;
     // structure of "format" depends on whether we're using pretty permalinks
     $format = empty( get_option('permalink_structure') ) ? '&page=%#%' : 'page/%#%/';
     echo paginate_links(array(
          'base' => get_pagenum_link(1) . '%_%',
          'format' => $format,
          'current' => $current_page,
          'total' => $total,
          'mid_size' => 4,
          'type' => 'list'
     ));
}

Izvor: http://wordpressexperts.net/how-to-add-pagination-in-wordpress-without-plugins-its-easy/

/* ----- GALLERY HACK ------- */
remove_shortcode('gallery');
add_shortcode('gallery', 'dz42_medium_gallery');

function dz42_medium_gallery($atts) {     	  
	$atts['size'] = 'galerija-thumbnail';
	return gallery_shortcode($atts);
}

change wordpress default gallery thumbnail size

Bravo Tomo! :)

Assume that we want to show 5 posts per page for category “WordPress” and 10 posts per page for category “News”, just open the functions.php file in your theme folder and insert these line into it:

add_action('pre_get_posts', 'diff_post_count_per_cat');
 
function diff_post_count_per_cat() {
    if (is_admin()) return;
 
    $cat = get_query_var('category_name');
    switch ($cat) {
        case 'wordpress':
            set_query_var('posts_per_page', 5);
            break;
        case 'wordpress/news':
            set_query_var('posts_per_page', 2);
            break;   
    }
}

Change “wordpress” and “news” into real category names of your blog. Note that in the code above, we use category slug, not original name. If the category is a child category, don’t forget to insert full path (i.e. “wordpress/news” in the example below).

Radi se o fajlu category.php, single_cat_title(); samo prikaze naziv kategorije bez linka. Ovaj kod prikazuje i link i naziv kategorije

$categories = $wp_query->query_vars;
$this_category = get_category_by_slug( $categories['category_name'] );
echo '
'.$this_category->name.'
';

Goes in the element of a theme, in header.php. Example plugin use: add JavaScript code.

Goes in footer.php, just before the closing tag. Example plugin use: insert PHP code that needs to run after everything else, at the bottom of the footer. Very commonly used to insert web statistics code, such as Google Analytics.

Typically goes in the Meta section of a Theme’s menu or sidebar; sidebar.php template. Example plugin use: include a rotating advertisement or a tag cloud.

Goes in comments.php directly before the file’s closing tag. Example plugin use: display a comment preview.