postid="category:17"    posts in a numeric category or categories
 postid="category:-17"   posts *not* in a numeric category
 postid="category:cakes" posts by category name
 postid="tag:37,38,53"   posts with numerically specified tag(s)
 postid="tag:chocolate"  posts by tag name
 postid="author:27"      posts by a specific author by ID
 postid="author:Todd"    posts by author name

Categories and tags can also have multiple values separated by commas (posts in any of the categories or tags) or ‘+’ plus signs (posts which are in all of the categories or tags).

When combined with a thumbnail image, or placed into a table or list, you can now create pages like:

• An author biography page, with automatic listing of the most recent posts by that author.
• A category overview page — say, “Dessert Recipes” — that automatically shows the most recent desserts, and a thumbnail for each.
• A page for a category — say, “France” — with a lead-in for the most recent articles with the “france” or “riviera” tags.

Apparently there were so many spam messages (over 17,000!) that Akismet would hang with some kind of unreported out-of-memory condition.  There was nothing in the log files to indicate what might be causing the error.

The result was a blank page with an address like:

http://www.example.com/wp-admin/index.php?action=akismet_recheck_queue

I was able to get Akismet filtering running by manually starting mysql:

$ mysql databasename -u dbusername -p

and then deleting all the very old unapproved comments:

mysql> delete from wp_comments where comment_approved = 0
       AND comment_date < '2010-1-1';

You can see how many unapproved comments Akismet will try and filter:

mysql> select count(comment_ID) from wp_comments
       where comment_approved=0;

and after Akismet runs awhile, you can monitor its progress by counting the number of messages flagged as spam:

mysql> select count(comment_ID) from wp_comments
       where comment_approved='spam';

This completely resolved the problem.

• Find the names and document-root of each website configured on your server
• Find the version of WordPress (if any) for each website, and the Subversion repository version used (if any).
• Sort these by name, owner UID, or WordPress version

Rename the .pl.txt file to .pl, chmod a+x so you can run it, and then:

# ./show_wp_versions.pl

which would display, for example,

Domain                         Version    Tracking Subversion  Owner
-----------                    --------   -------------------  -----
alphabetcompany.com             2.8       tags/2.8             alphabet
awkwardaardvark.com             2.7.1     tags/2.7.1           aardvark
brilliant-doorstops.co.uk       2.3                            dumbasapost

-n sorts by numeric version number; -u sorts alpha by UID.

Very handy when you’re supporting a large number of WordPress installs on a single server, to know who’s running what, and who needs to be updated!

NOTE: To install on a fresh system, you will probably need to:

# cpan
cpan[3]> install App::Info::HTTPD::Apache
cpan[1]> install SVN::Class::Info
cpan[2]> install Apache::ConfigParser

First we find the ID number of the parent page that we want to export. This process will export that page and all its sub-pages (children), sub-sub-pages, etc. You can find this by hovering over the “Edit” link in the WordPress “Pages/Edit” area and noting the “&post=number” section. In my case it was “2″ — that’s the number we will use below.

In wp-admin/includes/export.php, find the lines:

// grab a snapshot of post IDs, just in case it changes during the export
$post_ids = $wpdb->get_col("SELECT ID FROM $wpdb->posts $where ORDER BY post_date_gmt ASC");

Comment that out, and replace with:

# Export only a particular page and all its children
$post_ids = array();
$new_pages = array();
$new_pages[] = 2; # Parent page ID, which we will export, along with all its children
while (count($new_pages)) {
  $where = "WHERE post_parent IN (".join(',', $new_pages).")";
  foreach ($new_pages as $np) {
    $post_ids[] = $np;
  }
  $new_pages = array();
  $new_pages = $wpdb->get_col("SELECT ID FROM $wpdb->posts $where ORDER BY post_date_gmt ASC");
}
# $post_ids array now contains the pages we wish to export

Simply run the Export process and you will have just those pages.

• podPress – Podcast generator
  
• EasyTube – YouTube Plugin for WordPress

To install a fresh copy of WordPress, type the following at your command prompt, starting from the directory above where you want to install WordPress. These commands will create a directory “blog” for your blog, and then check out (Subversion command “co”), or extract from the repository, the stable version of WordPress you have chosen. Do not type the “$” characters — they are just indications of the command prompt. Here are the commands (assuming the version you want is 2.7.1):

$ mkdir blog
$ cd blog
$ svn co http://svn.automattic.com/wordpress/tags/2.7.1 .