This past weekend I spent some time playing around with Linux Mint 12. Last week, Linux Mint’s approach to the Gnome2-Gnome3-Unity fiasco was highlighted multiple times on slashdot.org. Linux Mint seeks to blend the aspects of these desktop environments into something that people actually want. They’ve given you the choice of which version of Gnome to run, and subsequently, the choice of which way you want to use your desktop environment: application-centered or task-centered. Anyway, it was a pleasant experience to fiddle with the ‘Lisa’ release candidate.

Without further commentary:

How to Create a Linux Mint 12 Bootable USB Drive

I based my exploration of creating a bootable USB drive on this post about Linux Mint 11, the process is essentially the same. I didn’t have any luck with the Startup Disk Creator, though, so I went with UNetbootin. Additionally, you don’t need to edit any configuration files with the below process.

1. Download UNetbootin

You can get it from it’s homepage on sourceforge or if you run Ubuntu or Linux Mint as your OS, run this command:

$ sudo apt-get install unetbootin
2. Grab one of the CD releases from Linux Mint.

I used the 32-bit iso without codecs, so that’s the only release for which I can vouch.

3. Insert your USB drive
4. Erase everything on your USB drive or format the USB drive
5. Open UNetbootin
6. Select the Diskimage option, the ISO option and insert the path to the iso you downloaded.


UNetbootin screenshot

7. Select the Type of drive (USB) to which you’re writing and enter the path to that drive

See above image. Note: your path may be different.

8. Click OK

UNetbootin should create your bootable USB drive for you!

9. Insert the USB drive into the computer you’d like to boot into Linux Mint 12
10. Restart the computer with the USB drive inserted

If your computer’s boot order isn’t set to start with USB, you’ll have to enter the boot menu. This is usually done by hitting the F12 key as soon as the computer starts and before the ‘Starting Windows…’ screen or any other screen shows.

11. Hit Enter or Wait…

If you’ve successfully booted from the USB drive, you’ll likely get a prompt that looks like this:

SYSLINUX 3.63 Debian-2008-07-15 EBIOS Copyright (C) 1994-2008 H. Peter Anvin
boot:

You can simply hit enter, and that will trigger the UNetbootin menu. If you don’t do anything, within 30 seconds UNetbootin will take over and give you a menu for selecting which item on the USB drive to boot.

12. Select ‘Start Linux Mint’

Ta da! That’s it

Web technologies are always improving, and at an enormous rate. The web is moving in a way that makes it possible to do things natively in the web browser where one once had to rely only on external scripts or images. This is a very exciting concept to modern web designers and front-end developers. Things like CSS3 give web browsers support for gradients, rounded corners, drop shadows, and other design elements previously only achieved by using images. Modern browsers also include support for transitions and animations using only CSS.

Check out this cool little nugget, made by Dan Eden, called animate.css (make sure you view the demo page in Safari, Chrome, or Firefox). Dan has compiled a great selection of animations using only CSS3 transitions for you to use. Simply add the animate.css stylesheet to your project and add a class to your element. It’s that easy to create awesome animations that use native web browser technologies.

One of the main benefits of using CSS transitions and animations over things like jQuery and other Javascript libraries is better performance. This is due to the fact that they are native to the web browser and can take advantage of hardware acceleration – the use of the computer’s hardware to perform functions – whereas external scripts cannot. In addition to this performance boost, CSS animations will generally look better since they can use hardware acceleration.

However, don’t get too crazy using only CSS animations. There is one major drawback and that is cross-browser compatibility. Currently the only browsers that support this technology are Chrome, Safari, and Firefox. Microsoft has promised support for CSS transitions in Internet Explorer 10, so it will one day be a reliable cross-browser technology – just not right now. It’s important to provide a fallback using a script like jQuery for those browsers which don’t support CSS transitions.

Clicking on the image to the right will take you to the version of our mobile site, though it obviously renders better when viewed with a mobile phone. The links on the pages will take you directly to our full-site, the mobile site is really designed to catch a visitor’s attention and drive them to contact us.

Have you launched a mobile-friendly version of your site? It takes about a week or so to launch a very simple site like the one we created for ourselves, for more complicated sites, or ones that will tie in to a content management system, it will obviously take longer.

Call us today to turn your site mobile friendly.

If you are checking that HTTPS is off, your logic will be fine, as that is the default value for the variable (and the only value for the variable on some debian servers). However, if you are checking that HTTPS is on, your logic will fail, as the HTTPS variable is never set. I was rewriting to control shifting from SSL to non-SSL, and in some cases this caused infinite loops, in others, code simply failed to ever evaluate to true.

The solution is to use the SERVER_PORT variable instead. I have always considered this to be less appropriate, because if someone decides to listen for SSL over a non-standard port HTTPS still works but a SERVER_PORT=443 check will fail. Keeping in mind that your server may (although it’s unlikely) require a unique port, try changing your conditions as follows:

# RewriteCond %{HTTPS} off   ## Always true
# RewriteCond %{HTTPS} on   ## Never true
RewriteCond %{SERVER_PORT} ^443$   ## Evaluates as expected
RewriteCond %{SERVER_PORT} !^443$   ## Evaluates as expected

Recently I was implementing a design in Drupal 7 which called for tables of alternating colors known variously as zebra striping, alternate row striping etc. While this design technique has been around for years it has been approached in various ways largely due to evolving standards. The challenge stems from their being no direct way to stripe or style one particular row differently from another in html without adding a class to it until CSS version 3. One article I liked advocates the use of CSS3 to do this which results in cleaner markup and and works without any javascript.  The downside of this is that CSS3 has patchy support across older browsers which many site visitors still use. In the end a combination of the CSS3 definitions and the jQuery (natively supported in Drupal) method outlined here maximized the number of users who would come to the site and see the table formatting at its best.

<script type=”text/javascript”>

$(document).ready(function(){

$(“table tr:nth-child(even)”).addClass(“alt”);

}); </script>

I hope you find this a useful example of the efforts we at Accella go to in order to keep clients, users and our design team happy!

The CentOS Testing repository comes to the rescue (CentOS provides a lot of very helpful repositories). They even have a HowTo PHP5.1 to 5.2 page. The problem with this page is that it includes some terribly inconvenient styling. A quick cut and paste yields a config page that carries indentation. Yum will fail to parse your configuration data if it is preceded by a space (or if a comment is preceded by space).

If you attempted to follow the wiki instructions, but instead found yourself staring at a “Config Error: File contains no section headers.” message, check the current CentOS-Testing.repo file on the CentOS/5 server. Notice the absence of any indentation preceding the repository section header, variables, and comments. Either use this version in /etc/yum.repos.d/CentOS-Testing.repo (just make sure you add an “includepkgs=php*” at the bottom!!!), or manually remove the indentation from the CentOS wiki version. After that, a simple “yum update” or “yum update php*” will update your server with PHP 5.2. Apache users need to restart apache with “/sbin/service apache restart” (or your preferred apache restarting technique), and PHP 5.2 is up and running on your web server.

Recently, I was working on a web service which required us to parse the data from the XML feed and to store it in the database. Normally this is a simple task which can be achieved by using PHP’s simple_xml library to parse the data. However, if the document has not been encoded properly, simple_xml will generate an XML.

Whenever an XML document is encoded, the encoding used should be provided in the document.
If the document was encoded with unicode, example, UTF-8, the following would be the first line of the:
<?xml version=”1.0″ encoding=”UTF-8″?>

In my case, the xml document was label as UTF-8, however it was an ascii document which contained non-acii characters. This created a major problem with the parser. The quick solution is to strip the non-ascii characters from the document.
This can be achieved with the following php code:

$jobs = file_get_contents(‘/home/mydir/doc.xml’);
$jobs = preg_replace(‘/[^(\x20-\x7F)]*/’,”, $jobs);

In order to achieve this objective, you need to run the following command to get a WebM (VP8/Vorbis) video. An encoding format supported by Firefox 4+, Chrome 6+ and Opera 10.6+:

ffmpeg -i input.avi -vcodec libvpx -acodec libvorbis -threads 4 output.webm

and to produce an mp4 (h264/mp3) for Safari 3+ and Internet Eplorer 9+:

ffmpeg -i input.avi -vcodec libx264 -acodec libmp3lame -preset slow -crf 22 -threads 0 output.mp4

then use the following syntax to write an html5 page that can run on all platforms:

<video width="480" height="640" controls>
  <source src="videos/dscn0470.mp4"  type='video/mp4; codecs="avc1.42E01E, mp4a.40.2"'>
  <source src="videos/dscn0470.webm" type='video/webm; codecs="vp8, vorbis"'>
</video>

svn propset

A typical command for ignoring a file in SVN is:

So, in Drupal, to ignore your settings.php file, you navigate to the sites/default directory and run this command:

For some reason, this never works for me. I end up creating a slew of properties all over the repository and none of my files are ignored in version control or removed from the svn status list.  This is where svn propedit comes into play.

svn propedit

svn propedit lets you edit a file that contains ignore patterns for the directory you specify as the last argument in the svn propedit command.

For example, in your sites/ folder of your Drupal installation run this command: 

Then, enter ‘settings.php’ into the file, save and exit the file.

For some reason, to me this seems like a much clearer approach to ignoring files.  It worked for me…once…I haven’t been able to duplicate it.

svn propget

To see all of the ignore properties in your project, navigate to the root directory of your project and run the svn propget command like this:

The Bottom Line

So, what does this all come down to? Instead of using SVN for your version control, use Git and forget about keeping track of directories and starting thinking of your files. If you can explain the svn:ignore property to me beyond what I’ve laid out here, please comment and educate me on setting properties on directories.

Steps to evaluating online code

• Is the source trustworthy?
• Can I understand the approach that someone else used to solve this problem?
• Does the solution cover all or almost all of my needs?
• Does it work when I plug it in?

Is the source trustworthy?

For community driven collaborate development models such as Drupal, trustworthiness is less of a concern. The community model of review allows for a base starting point of avoiding shadiness and malicious add-ons. I can see how long ago something was posted, roughly how many people are using it and if there are any open issues. Knowing that potentially thousands of other developers have reviewed this particular code and past revisions gives me piece of mind that I can use this with minimal fear that something inappropriate is going on behind the scenes.

For other sources such as forums and independent sites, I am typically more cautious. There is a lot of great content out there for php (and other languages of course) that isn’t neatly rolled up into a drupal module. When visiting such sites, I like to look for a few things before considering downloading code.

• Do they offer hashed checksums for verification that the code is presented as published by the original author?
• Is the code hosted on a reputable site e.g. sourceforge, github?
• Has someone I know recommended the module/ plug-in/ feature?
• Does it require you to install other non-standard libraries or elements?
• Do that have ads or links to disreputable materials?

Can I understand the approach that someone else used to solve this problem?

If I don’t understand how the code I’m reviewing manages to do what it does, I can’t in good conscience make use of it. I may need to look up unfamiliar function calls to become comfortable that it does what I says it does and that if I needed to make tweaks I could do so without breaking the rest of the code. Every programmer looks at a problem slightly differently and prefer particular devices. I need to evaluate the approach chosen as reasonable given the problem space in order to make it part of any system I am building. If the approach chosen is sloppy, erratic or is too specific for the problem I need to solve, I may use some of the logic but not the code itself as a base for a more complete solution of my own. Generally speaking, if someone has already spent time considering the problem I am facing, solved it and shared it, I should gratefully accept not having to formulate a new piece of code to do the same thing!

Does the solution cover all or almost all of my needs?

Sometimes you come across a piece of code that totally addresses a problem you are facing and you can easily adapt work you’ve already done to take advantage of it. Perhaps you’ve created a skeleton for a solution but haven’t accounted for all of the variations and this neat package has them covered. This can be the basis of a really great day

Other times you may come across a narrow solution that covers just one of several cases that you need to address. In these circumstances you need to evaluate the merits of copying the useful piece into your own module or working within the design of the existing module to add the missing elements. This really comes down to an evaluation of the effort it would take for you to wrap your problem solving inside someone else’s construct versus taking their partial solution and placing it within a broader approach that is more natural to you.

Does it work when I plug it in?

If a solution looks like it should work from reviewing the source code but doesn’t give you the right output or chokes when you attempt to integrate it into your system you need to determine how long you should spend trying to fix someone else’s code. It may be something simple such as not having a particular library installed or it could end up being really buggy or defective code. Estimate how long it would take to write that portion into new code before diving in to fix-it mode. Keep in mind that the goal for reusing existing code is to improve stability and decrease development time!

Code Reuse

Code reuse is a great way to solve problems efficiently and a great way to improve your own development skills by analyzing the approaches that other developers take to solve problems. Appropriate caution and being aware of the time you are spending on other people’s code allows for the kind of rapid, agile development that we at Accella do so successfully.