Japh » Development

Get yourself a Satellite developer

Japh — Sat, 30 May 2009 05:08:34 +0000

If you don’t already know, I recently started full-time freelance development. The idea is that anyone who needs development work done, wherever they are, can contact me to help out on their project.

Whether you are a freelance designer who needs some development done (or even some training), or a freelance developer who needs an extra pair of hands, or even a bigger business who needs to bring someone else in on a project… I’m available for hire!

I would love to hear any feedback on the new website too, so feel free to leave any comments in that regard as well.

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Custom default Gravatar in WordPress 2.7

Japh — Thu, 02 Apr 2009 03:45:06 +0000

If you’ve been using WordPress for a little while, and don’t really much like the default options you have to choose from when a commenter doesn’t have their own Gravatar, why not make your own?

Make yourself a little square image to use that matches in with your theme, and then insert the following line of code:

 echo get_avatar( $comment, 86, 'http://example.com/custom-default-av.png' ); ?>

Note: you must provide the full absolute URL for your image.

What this line does, is show a Gravatar for the user if they have one, and if not, show your custom one instead. The number “86″ is the pixel width and height you want the Gravatars to display at.

Remember that this will only work in WordPress 2.7+, or possibly in older versions if you have the Gravatar plugin installed (not tested).

Update: If you don’t know what a Gravatar is, check out the comments. The avatar’s shown beside each comment are automatically pulled in from Gravatar’s service, so you upload your avatar once, and it appears everywhere when you comment etc. Get yourself one here: Gravatar

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Time-sensitive CSS

Japh — Tue, 31 Mar 2009 09:18:28 +0000

Have you ever wanted to load a specific stylesheet depending on what time it is? It is actually very easy to do!

View Demo

I’m using jQuery in this just because it makes it look a little simpler, it’s not much more complex to do without jQuery… but let’s face it, you’re probably already using jQuery anyway, so why not

Make yourself a new file to put your javascript into, I’ve called mine “script.js”. Include the new javascript file by putting this line in your HTML section with the following line:

Now open your “script.js” file, and put the following lump of code into it:

// This line depends on jQuery, and tells the browser to kick off this stuff once
// everything's fully loaded
$(document).ready(function () {
    // These two lines make set a Date variable with the current date and time
    var currentDate = new Date();
    var currentHour = currentDate.getHours();
 
    // Here we're creating a new  to insert in the 
    var newCSS = document.createElement('link');
    newCSS.type = 'text/css';
    newCSS.rel = 'stylesheet';
 
    // This is where you can determine when to use which stylesheet.
    // If the current hour is before 9am or 8pm (or later), use "night.css"
    if (currentHour < 9 || currentHour >= 20) {
        newCSS.href = 'css/night.css';
    }
    // Otherwise, use "day.css"
    else {
        newCSS.href = 'css/day.css';
    }
    // This line actually does the deed, and attaches the selected stylesheet
    $("head").append(newCSS);
 
    // This line isn't necessary, it's just showing the actual time in the demo.
    $(".satellite").html(currentDate.toTimeString());
});

Read the commenting to understand what’s actually going on there, but that should do it! Easier than you thought, I bet

If you have any questions or suggestions, leave a comment!

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Sending scheduled emails with PHP

Japh — Fri, 06 Mar 2009 14:09:33 +0000

Ok, so there are two main topics being covered here:

Sending emails with PHP
Running PHP scripts with a cronjob

Sending emails with PHP

Step 1

First of all, we’re going to install the PEAR::Mail package. PHP’s built-in mail() function isn’t particularly secure, so using an actual SMTP email account seems nicer :)

If you don’t already have PEAR::Mail installed, you may need to request from your host that they install it. If you have SSH / shell access to your server, you can probably do it yourself by running the following command:

pear install mail

Now you should be able to use this library with the following code in the top of your PHP script:

require_once('Mail.php');

This may seem odd, because you have no Mail.php file in your web root, but trust me it works. This is because PEAR is in PHP’s path variables, so if it doesn’t find the Mail.php file in your web root, it already knows to look there.

Step 2

The next part is actually writing some PHP that will send a message. You will need a few details of your mail server for this bit, such as SMTP server name, your username and your password. You will also need an email address to send to, and one to send from, of course!


require_once "Mail.php"; // Inclusion of PEAR::Mail
$from = "Joe Bloggs ";
$to = "John Citizen ";
$subject = "Test message";
$message = 'Test message.';
$host = "smtp.domain.com";
$username = "jbloggs";
$password = "password";
$headers = array (
    'From' => $from,
    'To' => $to,
    'Subject' => $subject
);
// Now we will create an SMTP object with the appropriate details
$smtp = Mail::factory(
    'smtp',
    array (
        'host' => $host,
        'auth' => true,
        'username' => $username,
        'password' => $password
    )
);
// Here we actually send the email
$mail = $smtp->send($to, $headers, $message);
// And check for errors, or if the email was sent successfully
if (PEAR::isError($mail)) {
    echo("" . $mail->getMessage() . "
");
}
else {
    echo("Message successfully sent!
");
}
?>

I’ve put some comments in this script, just to make sure you know what’s going on, but basically that’s it!

Running PHP scripts with a cronjob

Step 3

Using cronjobs seems difficult, and some people are put off by the slightly archaic looking format… but they’re actually very simple. You put multiple entries (cronjobs) into the crontab, and then they run! Look at the following crontab entry:

0 * * * * /usr/local/bin/php -q /path/to/script/schedule.php

What this says is, everytime the minute is 0 (i.e. on the hour), run that command. Look at this crontab entry:

*/5 2 * * * /usr/local/bin/php -q /path/to/script/schedule.php

This one says, each time the minute is a multiple of 5 (i.e. every 5 minutes) and the hour is 2 (i.e. 2:00am), run that command.

So that’s basically it! With both those entries in the crontab, our emails will be sent every hour on the hour, and also every 5 minutes between 2:00am and 2:59am.

Hopefully this helps some people. If you have any questions, or if I made any mistakes, feel free to let me know in the comments :)

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Tracking memory usage

Japh — Fri, 06 Feb 2009 12:35:51 +0000

Recently I received a warning from my host that I was WAY over my memory limit. I had some long running processes going, and a few cron scripts that altogether were using about 220mb out of my 120mb of allowed memory usage… oops!

Anyway, there’s currently no way from my control panel to see how memory I’m currently using, I have to run a command from a terminal, and certainly no way to tell usage over time. So, after looking at a thread my hosting provider pointed me to, I decided to have a play with the Google Charts API!

This is a pretty rudimentary solution, but it’s working so far for me.

1. A very simple bash script

#!/bin/bash
ps -u username -o pid,rss,command | grep -e mpm -v | awk '{sum+=$2} END {print ",", sum}' >> /path/to/webroot/mem/memdata.csv

The script basically just outputs the current memory usage at the time of running and appends it to a CSV file.

2. Add the script to the crontab

By running the following command (or one similar), I edit my crontab:

crontab -e

I then insert this line:

0 * * * * /full/path/to/script/memlogger

So now that bash script will be run every hour, on the hour.

3. Writing a PHP script to display a Google Chart


// Settings
$max_mem = 120; // Your memory limit, in MB
$data_file = 'memdata.csv';
$chart_width = 550;
$chart_height = 400;
?>
DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Memory Usagetitle>
head>
 
<body>
<h2>Memory Usageh2>

$md = file_get_contents($data_file);
$md = preg_replace('/(\s+|\n)/', '', $md);
$md = explode(',', $md);
array_shift($md);
$max = 0;
$min = 0;
foreach ($md as $v) {
	if ($v > $max) {
		$max = $v;
	}
}
$base = 0;
if ($max > 0) {
	$base = ((($max_mem) * 1024) / $max) * 1;
	$base = round($base, 2);
}
?>
<p><img src="http://chart.apis.google.com/chart?cht=lc&chd=t:$md); ?>&chs=$chart_width; ?>x$chart_height; ?>&chxt=y,r&chxr=0,$min; ?>,$max; ?>|1,$min; ?>,$max; ?>&chds=$min; ?>,$max; ?>&chm=r,FF0000,0,$base; ?>,$base+0.005; ?>" />p>
body>
html>

This code basically just imports the data into an array, and then works a few things out for proper axis labelling, and away it goes! It’s pretty quick and dirty, and could probably have been done nicer… maybe I’ll come back and fix it up some time.

It also uses your memory limit amount to show a red line on the graph if you go over

Here’s the chart using some sample data:

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APIs and The Grey Album

Japh — Tue, 06 Jan 2009 14:05:09 +0000

Lately I’ve been playing around with a few different APIs. Getting the hang of using them and seeing what they can do. I’ve had a brief play with both the Flickr and Twitter APIs, and they’re both actually very user-friendly yet powerful.

I decided to build a simple photo album script using mostly PHP and jQuery to do the tricky parts, and the SimplePie library for actually importing the photo stream. I’ve called it The Grey Album, and though I probably wouldn’t call it a complete and comprehensive script, it seems to do the job. Any feedback is most welcome!

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Migrating from Windows to Ubuntu

Japh — Fri, 17 Oct 2008 08:18:53 +0000

I’ve always been interested in Linux as an operating system, but found too many reasons to go back to Windows. Linux was just a fun, geeky thing to play around with, but not really viable for everyday use.

I had dabbled in various Linux distributions. Gave Redhat and Mandrake a go, then installed Gentoo for a while, which was a brilliant learning experience. Then almost a year ago, I started playing around with Ubuntu a bit, and then I bought an Eee PC with Xandros installed to take travelling for a few months. The Eee PC was extremely handy to have while travelling, and I found that Linux was just fine for all the things I needed to do. So when I got back to work, I decided to just continue on, install Ubuntu and see how I went.

Essentially, I haven’t looked back. I now primarily use Ubuntu on my workstation at work, and on all my computers at home. As a web developer, I primarily work with open source technologies (PHP, Apache, MySQL, Python, etc.). I usually deploy my projects to a Linux-based server, so it actually makes a lot of sense to be building sites on Linux rather than Windows.

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DIY Dynamic DNS

Japh — Wed, 08 Oct 2008 11:17:05 +0000

I’ve setup my home network with a domain and wanted to be able to access my home server, from my office, on a subdomain.

However, as is probably the case for most of you, I have a dynamic IP address assigned to my router when it connects to the Internet through my ISP. So I decided I’d have to setup my own dynamic DNS process!

First things first, it was necessary to create the subdomain I wanted and point it to my home router’s external IP address, and also to change the configuration on my router to forward all traffic on port 80 to my home server’s internal IP address.

Next I needed a small script, PHP in this case, on my web server that simply outputs a tiny bit of XML with the current IP address of the visitor.

'; ?>
]]>

Then I wrote a small Python script that retrieves the IP address from the PHP script, and calls WebFaction’s server API to update the DNS record. This script runs on a crontab every hour, so if my IP address changes, I only have to wait an hour at most for an update.

#!/usr/bin/env python
import urllib
from xml.dom import minidom
import xmlrpclib
dyndomain = 'homeserver.example.com'
ip_url = urllib.urlopen('http://www.example.com/ip.php')
ip_dom = minidom.parse(ip_url)
ip_string = ip_dom.toxml()
ip_address = ip_dom.getElementsByTagName("ip")[0].childNodes[0].data
print ip_address
server = xmlrpclib.ServerProxy('https://api.webfaction.com/')
session_id, account = server.login('username', 'password')
server.delete_dns_override(session_id, dyndomain)
server.create_dns_override(session_id, dyndomain, ip_address, '', '', '', '')

Next I may add logging, so I can see when my IP address changes, but that’s optional really.

Note: Also, if someone can recommend a really good code-highlighter plugin for WordPress, I’d be very grateful!

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Fun with wild-card domain names

Japh — Tue, 16 Sep 2008 00:25:59 +0000

After seeing quite a few websites with dynamic content based on the domain name, I wanted to give it a try to see how difficult it was to achieve.

Here’s what I came up with: DueABootin.com

As it turns out, it wasn’t very difficult at all! (Especially being hosted through WebFaction, they make it even easier!)

First, I added the domain to my control panel, an added a subdomain of “*”, as you can see in the screenshot below.

And that’s really the hardest part, because PHP provides a nice little pre-defined variable called $_SERVER['HTTP_HOST'] which then gives us “example.dueabootin.com”, which we can pull apart and do with what we like.

Update: I’ve had a bit of a look into how difficult it might be to achieve the same results with cPanel, and it’s not much more difficult.

Create a new sub-domain called “*” which does not re-direct, just points to public_html/, and you should be fine. If that alone doesn’t work, then you may need to add an A record to your DNS zone file something like:

*.example.com. 14400 IN A 192.168.1.101

(don’t forget the trailing “.” after “.com”)

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A shell for your HTML

Japh — Sun, 23 Sep 2007 13:53:35 +0000

Ok, so I promised you the basic structure of an HTML page. So here is it:

My First HTML Page

This is the first paragraph on the page.

This is the second paragraph on the page, and it's a little bit longer than the first one. Try resizing your window to make it narrower to see the text wrap but maintain the paragraph spacing.

Now I’ll explain what it all means!

The first line tells the user’s browser some basic information about how to treat the code it finds in the document. It’s HTML, in fact, it says that it’s XHTML 1.0 Transitional. At this point, that won’t mean much to you, and it also won’t really matter to you. Essentially, the internet is currently transitioning from using HTML, to using XML for defining or describing the structure of a web page. So if you’re interested in reading more about XHTML, check out Wikipedia.

The next line is the opening html tag. Everything on your page should be placed within your opening and closing html tags.

Within your html tags, you should have a set of head tags, and a set of body tags. Everything on your page should be within one of these two. Content between the body tags, and various other things that we’ll get to later, between the head tags.

Two things we can see here already in the head tags, are a meta tag, and a title tag. Meta tags have a number of different uses. This particular one is defining the character set to be used on the page (UTF-8 in this case), you can also use them to define keywords for search engines and things like that.

The title tag defines what will appear in the user’s title bar on their browser. For example, on this page if you look up in the title bar of your browser, you’ll see it says “Japheth Thomson”, possibly followed by some arrows and some other text (depending how you got to this article).

For now, you can just copy and paste the code above into a new text file, save it as template.html, and then open it in a browser to see what happens.

You should get a blank white page, with the words “Untitled Document” in your title bar. Once you’ve got that working fine, try having a play with inserting paragraph tags as I talked about in my previous post to see what happens.

As an example, you should end up with something like this:

My First HTML Page

This is paragraph number on this HTML page.

This is the second paragraph. It's a bit longer than the first so that if you resize your window at all, you'll be able to see the text wrapping and maintaining the paragraph spacing above and below it.

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