This post has been created using the commandline.
$ cd $WP_ROOT $ wp post create /tmp/post-content.txt \ > --post_title="Posting from the commandline" \ > --post_category=16 \ > --post_status=publish
You will find additional information in $WP_ROOT/wp-includes/post.php.
Look at the parameters for “function wp_insert_post”. They translate into command line parameters for “wp post create”.
Also look at the various “register_post_status” definitions in that file if you want to understand what ‘publish’ is and which other states exist.
The category has been specified as a number. You can find these in the menu for the category tree. Category labels like “blog” don’t work here.