LAMP Web Development Blog

WordPress blogs server Atom and RSS feeds by default. One can outsource this job to a 3rd party services like feedburner. The existing built-in system in WP serves XML feeds on-the-fly. What that means is a if a feed reader/consumer requests your feed then WP is actually querying MySQL, doing all the back-end server side job and serves a hot, out of the oven, feed every time even if the posts are days or months old. This should not bother a very low traffic blog. But then you can set up WP to create physical static feed files using a plugin. This works for most of the scenarios. But I had a requirement that wanted a remote server to fetch and display those feeds. So even if I had set up a plugin to create static XMLfeeds to avoid server hits, the remote server would still need to query my server introducing network latency. There is a way out. WP has a built in update service that tells remote servers as soon as there is a change in blog. This service is known as “WP update service“. This is a sort of RPC service. You can provide WP a remote URL that should be notified as soon as a change in blog occurs. Now its up to that remote service to take an action on it. On my remote server I set up an action which as soon as receives this update message contacts my blog, fetches a feed and caches it locally. Now the remote server doesn’t need to look at my blog until and unless there is a change, of which it will be notified. One can take this a step further. In update services set up the url to a script on same blog that will connect to your blog and create XML feeds along side your blog files in feedsfolder. Use this code in your in wp-content/themes/{your theme}/functions.php

remove_action( 'wp_head', 'feed_links_extra', 3 ); // Removes the links to the extra feeds such as category feeds
remove_action( 'wp_head', 'feed_links', 2 ); // Removes links to the general feeds: Post and Comment Feed

This will stop printing the default URLs for feed in HTML source and in wp-content/themes/{your theme}/header.php add the URLs for actual feed files that now your script is creating. No need to install a plugin. The only drawback I see here is when you update your skin you loose this particular customisation. Other than that its a pretty good way to create static XML feed files and save your server some hassles.

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Programmers are lazy creatures. Any given programmer would love get things done with lesser keystrokes. For instance, find and replace all in multiple files. I was setting up a project on my localhost that some other guy had done. That guy wasn’t a real programmer otherwise what I did would have not been required at first place. The great soul hard-coded all the hyperlinks. What now? I thought of firing an editor and doing a find and replace all by creating a project. Simple. No. I can use grep/egrep to find things then obviously I can chain it to some other command and replace that text. Yes. I am lazy, so instead of experimenting I did some googling. Here is how to do this. Find all files, recursively of course, in current working directory that contain “teh” and replace them with “the”.

egrep -lRZ "teh" ./ | xargs -0 -l sed -i -e 's/teh/the/g'

egrep/grep takes further arguments like type of files to look for, example egrep “teh” *.txt ./ will search for all text files in current working direcotry that contain “teh”. Cool!

So, you can safely say, I can haz teh Linux power!

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