WordPress - Export taxonomies or categories

export_them_all.php

<?php

function just_export_damn_taxonomies($taxs = array(), $include_cats = false, $include_tags = false) {
	$WXR_VERSION = '1.2';
		
	// functions from 'wp-admin/includes/export.php'
	function wxr_cdata($str) {
		if (seems_utf8 ( $str ) == false)
			$str = utf8_encode ( $str );
			
			// $str = ent2ncr(esc_html($str));
		$str = '<![CDATA[' . str_replace ( ']]>', ']]]]><![CDATA[>', $str ) . ']]>';
		
		return $str;
	}
	function wxr_site_url() {
		// ms: the base url
		if (is_multisite ())
			return network_home_url ();
			// wp: the blog url
		else
			return get_bloginfo_rss ( 'url' );
	}
	function wxr_cat_name($category) {
		if (empty ( $category->name ))
			return;
		
		echo '<wp:cat_name>' . wxr_cdata ( $category->name ) . '</wp:cat_name>';
	}
	function wxr_category_description($category) {
		if (empty ( $category->description ))
			return;
		
		echo '<wp:category_description>' . wxr_cdata ( $category->description ) . '</wp:category_description>';
	}
	function wxr_tag_name($tag) {
		if (empty ( $tag->name ))
			return;
		
		echo '<wp:tag_name>' . wxr_cdata ( $tag->name ) . '</wp:tag_name>';
	}
	function wxr_tag_description($tag) {
		if (empty ( $tag->description ))
			return;
		
		echo '<wp:tag_description>' . wxr_cdata ( $tag->description ) . '</wp:tag_description>';
	}
	function wxr_term_name($term) {
		if (empty ( $term->name ))
			return;
		
		echo '<wp:term_name>' . wxr_cdata ( $term->name ) . '</wp:term_name>';
	}
	function wxr_term_description($term) {
		if (empty ( $term->description ))
			return;
		
		echo '<wp:term_description>' . wxr_cdata ( $term->description ) . '</wp:term_description>';
	}
	
	
	if ( !empty($taxs) ) {
		$custom_terms = (array) get_terms( $taxs, array( 'get' => 'all' ) );
	}
	
	if ($include_tags) {
		$tags = (array) get_tags(array('get' => 'all'));
	}
	if ($include_cats) {
		$categories = (array) get_categories(array('get' => 'all'));
	}
	$sitename = sanitize_key( get_bloginfo( 'name' ) );
	if (!empty($sitename)) 
		$sitename .= '.';
	$filename = $sitename . 'wordpress.' . date( 'Y-m-d' ) . '.xml';

	header( 'Content-Description: File Transfer' );
	header( 'Content-Disposition: attachment; filename=' . $filename );
	header( 'Content-Type: text/xml; charset=' . get_option( 'blog_charset' ), true );

	if(!empty($categories)) {
		// put categories in order with no child going before its parent
		while ($cat = array_shift($categories)) {
			if ($cat->parent == 0 || isset($cats[$cat->parent]))
				$cats[$cat->term_id] = $cat;
			else
				$categories[] = $cat;
		}
	}

	if (!empty($custom_terms)) {
		// put terms in order with no child going before its parent
		while ($t = array_shift( $custom_terms ) ) {
			if ($t->parent == 0 || isset($terms[$t->parent]))
				$terms[$t->term_id] = $t;
			else
				$custom_terms[] = $t;
		}
	}

	echo '<?xml version="1.0" encoding="' . get_bloginfo('charset') . "\" ?>\n";
	?>
	<?php the_generator( 'export' ); ?>
	<rss version="2.0"
		xmlns:excerpt="http://wordpress.org/export/<?php echo $WXR_VERSION; ?>/excerpt/"
		xmlns:content="http://purl.org/rss/1.0/modules/content/"
		xmlns:wfw="http://wellformedweb.org/CommentAPI/"
		xmlns:dc="http://purl.org/dc/elements/1.1/"
		xmlns:wp="http://wordpress.org/export/<?php echo $WXR_VERSION; ?>/"
	>
	<channel>
		<title><?php bloginfo_rss( 'name' ); ?></title>
		<link><?php bloginfo_rss( 'url' ); ?></link>
		<description><?php bloginfo_rss( 'description' ); ?></description>
		<pubDate><?php echo date( 'D, d M Y H:i:s +0000' ); ?></pubDate>
		<language><?php bloginfo_rss( 'language' ); ?></language>
		<wp:wxr_version><?php echo $WXR_VERSION; ?></wp:wxr_version>
		<wp:base_site_url><?php echo wxr_site_url(); ?></wp:base_site_url>
		<wp:base_blog_url><?php bloginfo_rss( 'url' ); ?></wp:base_blog_url>
	<?php 
	if( !empty($cats) ):
		foreach ( $cats as $c ) : ?>
		<wp:category><wp:term_id><?php echo $c->term_id ?></wp:term_id><wp:category_nicename><?php echo $c->slug; ?></wp:category_nicename><wp:category_parent><?php echo $c->parent ? $cats[$c->parent]->slug : ''; ?></wp:category_parent><?php wxr_cat_name( $c ); ?><?php wxr_category_description( $c ); ?></wp:category>
	<?php endforeach; 
	endif;
	?>
	<?php
	if( !empty($tags) ): 
		foreach ( $tags as $t ) : ?>
		<wp:tag><wp:term_id><?php echo $t->term_id ?></wp:term_id><wp:tag_slug><?php echo $t->slug; ?></wp:tag_slug><?php wxr_tag_name( $t ); ?><?php wxr_tag_description( $t ); ?></wp:tag>
	<?php endforeach; 
	endif;	
	?>
	<?php 
	if( !empty($terms)):	
		foreach ( $terms as $t ) : ?>
		<wp:term><wp:term_id><?php echo $t->term_id ?></wp:term_id><wp:term_taxonomy><?php echo $t->taxonomy; ?></wp:term_taxonomy><wp:term_slug><?php echo $t->slug; ?></wp:term_slug><wp:term_parent><?php echo $t->parent ? $terms[$t->parent]->slug : ''; ?></wp:term_parent><?php wxr_term_name( $t ); ?><?php wxr_term_description( $t ); ?></wp:term>
	<?php endforeach; 
	endif;
	?>
	<?php do_action( 'rss2_head' ); ?>
	</channel>
	</rss><?php	
	die();
}


if (current_user_can("manage_options") && is_admin() && isset($_GET['export_taxes'])) {
    just_export_damn_taxonomies(array("mytaxonomy"));
}

// visit wp-admin/?export_taxes be happy

I hereby place this to public domain.

Bits and pieces may be GPL'd, because they are from wordpress and some other plugin which included useless stuff.