update_option( 'admin_email', 'admin@example.com' );
A concise list of commonly-used options is below.
'admin_email' – E-mail address of blog administrator.
'blogname' – Weblog title; set in General Settings.
'blogdescription' – Tagline for your blog; set in General Settings.
'blog_charset' – Character encoding for your blog; set in Reading Settings.
'date_format' – Default date format; set in General Settings.
'default_category' – Default post category; set in Writing Settings.
'home' – The blog’s home web address; set in General Settings.
'posts_per_page' – Maximum number of posts to show on a page; set in Reading Settings.
'posts_per_rss' – Maximum number of most recent posts to show in the syndication feed; set in Reading Settings.
'siteurl' – WordPress web address; set in General Settings. Warning: This is not the same as get_bloginfo( 'url' ) (which will return the homepage url), but as get_bloginfo( ‘wpurl’ ).
'template' – The current theme’s name.
'start_of_week' – Day of week calendar should start on; set in General Settings.
'upload_path' – Default upload location; set in Media Settings.
'users_can_register' – Whether users can register; set in General Settings.
There are many more options available, a lot of which depend on what plugins you have installed.
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