Technology Tales

A quick way to do an update

Here's a quick way to get the latest updates on your PC using the command line if you are using Ubuntu or Debian:

sudo apt-get update && sudo apt-get upgrade

Of course, you can split these commands up if you prefer to look before you leap. At the very least, it's so much slicker than the GUI route.

Recursive FTP with the command line

Here's a piece of Linux/UNIX shell scripting code that will do a recursive FTP refresh of a website for you:

lftp <<~/Tmp/log_file.tmp 2>>~/Tmp/log_file.tmp

open ${HOSTNAME}

user ${USER} ${PSSWD}

mirror -R -vvv "${REP_SRC}" "${REP_DEST}"

EndFTP

When my normal FTP scripting approach left me with a broken WordPress installation and an invalid ticket in the project's TRAC system that I had to close, I turned to looking for a more robust way of achieving the website updates and that's what led me to seek out the options available for FTP transfers that explicitly involve directory recursion. The key pieces in the code above are the use of lftp in place of ftp, my more usual tool for the job, and the invocation of the mirror command that comes with lftp. The -R switch ensures that file transfer is from local to remote (vice versa is the default) and -vvv turns on maximum verbosity, a very useful thing when you find that it takes longer than more usual means. It's all much slicker than writing your own script to do the back-work of ploughing through the directory structure and ensuring that the recursive transfers take place. Saying that, it is possible to have a one line variant of the above, but the way that I have set things up might be more familiar to users of ftp.

An alternative use for Woopra

While the once a day reporting cycle of Google Analytics is all very fine, the availability of real time data does have its advantages. WordPress.com's Stats plugin goes some way to serving the need, only for Woopra to trump it in every way apart from a possible overkill in the amount of information that it makes available. The software remains extremely useful despite being in the beta phase and occasionally crashing.

One of its uses is seeing if there are people visiting your website at a time when you might be thinking of making a change like upgrading WordPress. Timing such activities to avoid a clash is a win-win situation: a better experience from your visitors and more reliable updates for you. After all, it's effortless to make a poor impression and an unreliable site will do that faster than anything else, so it's paramount that your visitors do not get on the receiving end of updates, even if they are all for the better.

WordPress plugin for removing post revisions from database

WordPress 2.6 added post revisions as a new feature that is turned on by default. In an earlier post, I described how you could control this by editing wp-config.php and there are a number of plugins that purport to provide the same level of control through the administration screens. Even so, I decided to look at things from the housekeeping side of things and create my own plugin for clearing the database of revisions at one swoop. Currently, it takes out all revisions, but I am thinking of adding the facility for selecting which revision to keep and which to delete. It goes without saying that you should back up your database first in case anything might go wrong.

Download Remove Revisions 1.0

Getting VirtualBox working on Ubuntu after a kernel upgrade

In previous posts, I have talked about getting VMware Workstation back on its feet again after a kernel upgrade. It also seems that VirtualBox is prone to the same sort of affliction. However, while VMware Workstation fails to start at all, VirtualBox at least starts itself even if it cannot get a virtual machine going and generates errors instead.

My usual course of action is to fire up Synaptic and install the drivers for the relevant kernel. Looking for virtualbox-ose-modules-[kernel version and type] and installing that usually resolves the problem. For example, at the time of writing, the latest file available for my system would be virtualbox-ose-modules-2.6.24-19-generic.  If you are a command line fan, the command for this would be:

sudo apt-get install virtualbox-ose-modules-2.6.24-19-generic

The next thing to do would be to issue the command to start the vboxdrv service, and you'd be all set:

sudo /etc/init.d/vboxdrv start

There is one point of weakness (an Achilles heel, if you like) with all of this: the relevant modules need to be available in the first place and I hit a glitch after updating the kernel to 2.6.24-20 when they weren't; I do wonder why Canonical fail to keep both in step with one another and why the new kernel modules don't come through the updates automatically either. However, there is a way around this too. That means installing virtualbox-ose-source via either Synaptic or the command line:

sudo apt-get install virtualbox-ose-source

The subsequent steps involve issuing more commands to perform a reinstallation from the source code:

sudo m-a prepare

sudo m-a auto-install virtualbox-ose

Once these are complete, the next is to start the vbox drv as described earlier and to add yourself to the vboxusers group if you're still having trouble:

sudo adduser [your username] vboxusers

The source code installation option certainly got me up and running again, and I'll be keeping it on hand for use should the situation raise its head once more.

Another alpha release of Ubuntu 8.10 is out

It's probably about time that I drew attention to Ubuntu's The Fridge. While the strap line says, "News for Human Beings", it seems to be the place to find out about development releases of the said Linux distribution. Today, there's a new alpha release of Intrepid Ibex (8.10) out, and they have the details. As for me, I'll stick to updating my installed 8.10 instance using Synaptic rather than going through the whole risky process of a complete installation following a download of the CD image. Saying that, it would be nice to see the System Monitor indicating which alpha release I have. I didn't notice anything very dramatic after I did the update, apart maybe from the hiding away of boot messages at system startup and shutdown or the appearance of a button for changing display settings in the panel atop the desktop.

Losing formatting with Windows copying and pasting

Copy and pasting between Windows programs can cause unwanted formatting to be carried over. Copying text from Internet Explorer into Outlook is one example of this that I see a lot, and Word to Word does it too. A trick that I picked up for avoiding this copying of formatting comes from a while back: copying into Notepad and pasting from there. Doing the copy/paste shuffle in that way strips off the formatting baggage and allows the default formatting for the particular destination to be applied. There may be other and slicker ways to do this, but what I have described works for me.

How much space is that folder taking up on your disk?

On Windows, it's a matter of right-clicking on the folder and looking in its properties. I am sure that there is a better way of doing it in that ever pervasive operating system but, in the worlds of Linux and UNIX, the command line comes to the rescue as it is wont to do. What follows is the command that I use:

du -sh foldername

The s option makes it present the total space taken up; leaving it out gets you a breakdown of how much space the subfolders are taking up as well. The h makes the sizes output more friendly to human eyes with things like 10K, 79M and 51G littering what you get. The command itself is a much shorter way of saying "print disk usage". It's all quick and easy when you know it, and very useful in this age of ever-increasing data volumes.

Controlling the post revision feature in WordPress 2.6

While this may seem esoteric for some, I like to be in charge of the technology that I use. So, when Automattic included post revision retention to WordPress 2.6, I had my reservations about how much it would clutter my database with things that I didn't need. Thankfully, there is a way to control the feature, but you won't find the option in the administration screens (they seem to view this as an advanced setting and so don't want to be adding clutter to the interface for the sake of something that only a few might ever use); you have to edit wp-config.php yourself to add it. Here are the lines that can be added and the effects that they have:

Code: define('WP_POST_REVISIONS','0');

Effect: turns off post revision retention

Code: define('WP_POST_REVISIONS','-1');

Effect: turns it on (the default setting)

Code: define('WP_POST_REVISIONS','2');

Effect: only retains two previous versions of a post (the number can be whatever you want, so long as it's an integer with a value more than zero).

Update (2008-07-23):

There is now a plugin from Dion Hulse that does the above for you and more.

A first look at Ubuntu 8.10

I must admit that my curiosity got the better of me when screenshots of Ubuntu's 8.10, otherwise known as Intrepid Ibex, started to make their appearance. Since it is only at alpha2 stage, it's definitely a no-no for production systems. However, it does run surprisingly smoothly even at this stage. Yes, I have seen rough edges and the biggest of them all has made me install it onto my spare PC; there is certainly a tendency for systems to hang when you try running 8.10 in virtual machines, my preferred method for these kinds of explorations. Try it in VirtualBox and kernel panic messages ensue while you can log in on VMware Workstation only for the desktop never to load. While those could be major deficiencies for some, they have both been reported, with the former being seen by many and the latter being flagged by my own self.

Because I was using a version with the alternate installer, the usual slickness that we expect of Ubuntu installations wasn't apparent. Though I am sure that will change in time for the final release, I didn't find it too taxing to get things going with this means. Despite current changes, I expect a more familiar interface will return during later development cycles, certainly well before the final version is released. Because I was installing over the top of a previous Ubuntu installation, I didn't want to lose everything, but I needed to leave it to wipe out the previous root system partition for it to continue without freezing. Since my home directory resides on a separate partition, the transition occurred smoothly, with settings like desktop backgrounds being automatically detected without any complications. One thing that might annoy some is that all this takes manual intervention; you don't get the sort of non-destructive and seamless upgrade capability that openSUSE 11 gives.

What you get when the installation is completed is a Linux desktop that won't look too different from what we are used to using. The update introduces the New Human theme, featuring elegant chocolate-coloured elements that replace the previous default orange-brown colour scheme. They need to sort out a bug (another of my reports)  where black text is being displayed on dark backgrounds on the default display of dropdown menus in Firefox and maybe look into why changing the level of enhancements from Compiz Fusion messes up the display of the workspace switcher in the task bar, but it's fine apart from this.

Otherwise, it's a case of steady as she goes with OpenOffice 2.4, Firefox 3 and so on. That may change as time goes on, with OpenOffice 3 looming on the horizon. For some, all this continuity is all well and good, but I could foresee comments front some parts that nothing dramatic is happening, and that Ubuntu cannot afford to stand still with the advances of Fedora, openSUSE, Mandriva and so on. Saying that, I like the continuity because it doesn't mean that my apple cart is going to get overthrown now and again. Indeed, you could say that the whole Linux distribution market has matured very nicely with evolution being the order of the day and I suppose that Ubuntu needs to be seen to be evolving more than perhaps it has been doing.

In summary, it's early days for Intrepid Ibex, yet it works well even at this stage. In fact, it is running sufficiently so that I am writing this very post in a Firefox session running on the thing.  It'll be interesting to see how it goes from here and if any more pleasant surprises are visited upon us. After the "safety first" approach of Hardy Heron, I suppose that Canonical can feel a little more adventurous, so we'll see what comes. Meanwhile, Here are a few screenshots below for your perusal: