I have a Dell XPS L702x Laptop and the wireless is dodgy in Ubuntu 11.04. By Dodgy I mean it drops out and doesn’t automatically connect very often especially when a Ethernet cable is unplugged. It seems the problem is that Ubuntu doesn’t get on well with wireless-N (perhaps the driver is buggy?). I fixed it by disabling wireless N (but leaving G working):
First check to see that b, g and n is enabled:
> iwconfig
wlan0 IEEE 802.11bgn ESSID:"WKIXNTOM"
we need:
wlan0 IEEE 802.11bg ESSID:"WKIXNTOM"
To disable Wireless N, create a file called /etc/modprobe.d/iwlagn.conf and put the disable incarnation in it:
> sudo vi /etc/modprobe.d/iwlagn.conf
add:
options iwlagn 11n_disable50=1 11n_disable=1
Restart the computer to finish.
I agree this isn’t a ideal solution (to say the least!), but it’ll do for now.
Update after 2 months: Wireless has been reliable and steady since making the above change.
Update (15/Oct/11): This “hack” is a disaster for Ubuntu 11.10 Oneiric Ocelot, it causes Wireless to fail to load. Be sure to remove the /etc/modprobe.d/iwlagn.conf file when upgrading to Ubuntu 11.10. I found this issue the hard way: askubuntu question.
1 Comment | 
Category: Technical | Tags: CommandLine, Ubuntu | 
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Posted by Tom
Did you know that WordPress sends you emails when you get a new blog comment? I didn’t – because it has never worked for me. But once I knew it was supposed to email me I looked into it and found a fix.
Setup: My setup is running WordPress.org on a Ubuntu 9.04 box called Butterfree with sendmail installed.
The problem was that the Return-Path header in my outgoing mails wasn’t valid which caused some mail recipients to reject the mail, while other less picky ones, accepted the mail fine (e.g. gmail). The Return-Path header that sendmail was using looked something like this:
Return-Path: <www-data@butterfree.bitvolution.com>
I found this by changing the admin email from the one that didn’t work to a gmail one, then posting a test comment on one of my posts. Then I waited for the email to arrive in gmail and selected “show original” from the gmail interface. A quicker way is to check the entries in /var/log/mail.log.
In order to fix the issue, I configured the return path in emails sent from WordPress (i.e. PHP) to something different using the -f parameter for sendmail:
sudo emacs /etc/php5/apache2/php.ini
Find the sendmail_path and uncomment it and add the -f flag:
; -f will set the "return-path" headers.
sendmail_path = /usr/sbin/sendmail -i -t -f sendmail@bitvolution.com
Doing this solved this issue so I now get email about new comments.
My fix feels a bit of a hack. I would be interested in how to solve this problem the right way, so let me know if you can give me some advice. For example, perhaps I should have done something with my DNS settings for my domain?
No Comments » | Category: Technical | Tags: Sendmail, Ubuntu, Wordpress | Permalink
Posted by Tom
I used to think that a hard part of scaling a website from one webserver to two webservers was sharing the sessions between the machines to keep the users logged in whichever machine they were served by. I was pleasantly surprized that it is possible to accomplish sharing sessions between two servers by changing only 5 lines in the php.ini file (the 2 biggies are session.save_handler and session.save_path).
Here is a solution for RHEL 5.5:
No Comments » | Category: Technical | Tags: PHP | Permalink
Posted by Tom
In WordPress 3.0, my WordPress logo image (on the left) broke. So I opened a bug and six weeks and 100 bug comments later, I have upgraded to 3.01 and it is working again. Thanks guys!
The reason why the logo image was broken was quite interesting(?)… In v3.0 WordPress automatically started auto-correcting Wordpress to WordPress (i.e. Word-lowercase-p-ress to Word-uppercase-P-ress) and because my image file name was called “WordpressLogo_blue-m.png”, the auto-correction was breaking the link. Auto-correction shouldn’t cause links to break and it seems that v3.01 fixes it.
The filter function that does this auto-correction is called “capital_P_dangit” – The WordPress guys are obviously pretty frustrated by this spelling mistake!
Old filter (v3.0):
Home
function capital_P_dangit( $text ) {
return str_replace( 'Wordpress', 'WordPress', $text );
}
New filter (v3.01):
function capital_P_dangit( $text ) {
// Simple replacement for titles
if ( 'the_title' === current_filter() )
return str_replace( 'Wordpress', 'WordPress', $text );
// Still here? Use the more judicious replacement
static $dblq = false;
if ( false === $dblq )
$dblq = _x('“', 'opening curly quote');
return str_replace(
array( ' WordPress', '‘WordPress', $dblq . 'Wordpress', '>Wordpress', '(WordPress' ),
array( ' WordPress', '‘WordPress', $dblq . 'WordPress', '>WordPress', '(WordPress' ),
$text );
}
No Comments » | Category: Technical | Tags: Bug, Wordpress | Permalink
Posted by Tom
On this WordPress theme, the sidebar is quite small (only 220px) and the default WordPress tag cloud widget was producing tags that were clipped in a ugly manner. By default, the WordPress tag cloud widget has a maximum font size of 22px so I was looking for a way to reduce it.
Note: If you are not a theme editor, you might find it easier to just install a suitable tag cloud plugin, e.g. Configurable Tag Cloud (CTC).
The WordPress tag cloud widget already allows you to specify various options including the largest font size, e.g. <?php wp_tag_cloud('largest=18'); ?> so we only need to create a new widget that overrides the default widget and then unregister the default widget so there aren’t two widgets with the same name in the “Available Widgets” dashboard page. We can register our own widget using register_sidebar_widget and we can unregister the default tag cloud widget using unregister_widget('WP_Widget_Tag_Cloud');.
This is the code you need – put it in the functions.php file in your WordPress theme folder:
add_action("widgets_init", array('Tag_cloud_withLimitedFontSize', 'register'));
/** Widget - Override the default WordPress tag cloud BUT cap the largest font size to 18 (instead of 22)\
because at 22 some tags don't fit in the sidebar. */
class Tag_cloud_withLimitedFontSize
{
function widget($args){
echo $args['before_widget'];
echo $args['before_title'] . 'Tags' . $args['after_title'];
echo wp_tag_cloud('largest=18');
echo $args['after_widget'];
}
function register()
{
register_sidebar_widget('Tag Cloud', array('Tag_cloud_withLimitedFontSize', 'widget'));
unregister_widget('WP_Widget_Tag_Cloud');
}
}
If there’s a better way to do this, please let me know.
No Comments » | Category: Technical | Tags: PHP, WebDevelopment, Wordpress | Permalink
Posted by Tom
A website that I was working on suddenly started crashing Firefox 3.6 on my PC (Ubuntu 9.10, 64bit). I’m talking a full out hang with 100% CPU usage and a frozen mouse and keyboard and the only way to recover is to remote login from a 2nd PC and kill the Firefox process.
I found the cause of the crash and it was a single line of recently added CSS code at the top of the websites stylesheet: body { opacity: 0.9999; }
So, if you run a website, be careful of non-100% opacity when it affects many elements. I have hosted a page that reproduces the issue and found a bug that tracks the issue: #279890. This CSS is also a problem on Windows – it causes text to blur horribly in IE 7 in some situations.
What is that CSS for anyway? Firefox 2.0 on Macs used to have a problem where text could dim or get bold or flicker when a animated effect that changed the opacity of an element was used. It was caused because the use of a opacity filter triggered the Gecko rendering engine to switch from the operating system’s method of anti-aliasing to its own internal method. Whenever opacity dropped below 100% the mode switched and resulted in a defect such as a flicker or blink. The fix was simple – all that was needed was to add body { -moz-opacity: 0.9999; } to the stylesheet because it would force Firefox to use a consistent text rendering method.
No Comments » | Category: Technical | Tags: Bug, Firefox, WebDevelopment | Permalink
Posted by Tom
A typical use case for a hidden page might be so you can store your website licensing agreement or image attribution links without having it explicitly in the main navigation links – most folk link to their licensing agreement in the footer.
If you want to have a page on your self-hosted WordPress website that is accessible via a URL but not directly linked or advertised on the site, you have several options:
<?php wp_list_pages('depth=1'); ?><?php wp_list_pages('exclude=69' ); ?> If you do this you can automatically hide additional pages by making them a sub-page of the hidden page.<?php require_once(dirname(__FILE__) . '/../../../wp-blog-header.php'); ?>Note: WordPress does have a “Private” checkbox that you can tick in the visibility section of the publish options. However, private pages will not be accessible via any URL.
No Comments » | Category: Technical | Tags: Wordpress | Permalink
Posted by Tom
The following list is 10 favourite pieces of software which I’m thankful for every single day:
No Comments » | Category: Technical | Tags: List, Software | Permalink
Posted by Tom
The hardware behind Bitvolution is called “Butterfree“, he’s based in Germany (www.hetzner.de):
No Comments » | Category: Technical | Tags: Toys | Permalink
Posted by Tom
If you have a font file with a “ttf” extension you can easily install it in Ubuntu (v9.04) and use it in applications such as the Gimp. Essentially, all you have to do is drop it in the correct folder:
The following text was created in the Gimp: It uses 3 free fonts, the “B” is Heavy Data, the “it” is Sans Bold and the “volution” is Ballpark:
No Comments » | Category: Technical | Tags: Fonts, Graphics, Ubuntu | Permalink
Posted by Tom