Wordpress Custom Permalink for Just Posts

Question

My Wordpress install has three post types: pages, posts, and portfolio. The current structure is as follows:

• page: example.com/page-name,
• post listing page: example.com/blog,
• individual post: example.com/post-name,
• portfolio listing page: example.com/portfolio,
• individual portfolio post: example.com/portfolio/portfolio-name.

The thing I'd like to change is the individual post permalink, but nothing else. I'd like it to become example.com/blog/post-name.

I can't find documentation that shows how to make this change without affecting the other types.

EDIT : My current permalink structure is set up to be /%postname%/, and under Reading Settings, my posts page is set to Blog.

register_post_type('portfolio', array(  
'label' => 'Portfolio Items',
'description' => '',
'public' => true,
'show_ui' => true,
'show_in_menu' => true,
'capability_type' => 'post',
'hierarchical' => true,
'rewrite' => array('slug' => 'portfolio'),
'with_front' => false,
'query_var' => false,
'has_archive' => true,
'exclude_from_search' => false,
'supports' => array('title','editor','excerpt','trackbacks','custom-fields','comments','revisions','thumbnail','author','page-attributes'),
'taxonomies' => array('category','post_tag'),
'labels' => array (
    'name' => 'Portfolio Items',
    'singular_name' => 'Portfolio Item',
    'menu_name' => 'Portfolio Items',
    'add_new' => 'Add Portfolio Item',
    'add_new_item' => 'Add New Portfolio Item',
    'edit' => 'Edit',
    'edit_item' => 'Edit Portfolio Item',
    'new_item' => 'New Portfolio Item',
    'view' => 'View Portfolio Item',
    'view_item' => 'View Portfolio Item',
    'search_items' => 'Search Portfolio Items',
    'not_found' => 'No Portfolio Items Found',
    'not_found_in_trash' => 'No Portfolio Items Found in Trash',
    'parent' => 'Parent Portfolio Item',
)
));

Answer 1

You simply have to set /blog/%postname%/ as your permalinks structure, this will not change your pages permalinks.

And to keep your portfolio permalinks, you should set with_front to false when you register this post type.

'with_front' => bool Should the permastruct be prepended with the front base. (example: if your permalink structure is /blog/, then your links will be: false->/news/, true->/blog/news/). Defaults to true

EDIT 1 : You should probably flush Wordpress rewrite rules after that.

EDIT 2 : with_front param is a rewrite param :

'rewrite' => array('slug' => 'portfolio', 'with_front' => false),