Technology Tales

Ubuntu 9.04 and Tracker

Shortly after it was released, I did the upgrade shuffle very painlessly, and it didn't take up so much time either. There was only one issue: Tracker falling over, complaining about corrupted indices. That got it removed from my system using apt-get remove (apt-get purge is another option, especially if you need to rid yourself of nefarious configuration files). After having a bit of a dig around the web, I found that I wasn't the only one seeing the problem. To me, it looks as if the upgrade to 9.04 doesn't work so well when it comes to Tracker, and it needs to be removed and reinstalled to ensure that all required dependencies are correctly set in place. Since I restored it on my system, all is working without complaint. Other than the Tracker issue, it has been a case of another uneventful upgrade. Though the evolutionary path that Ubuntu is following may disappoint anyone looking for excitement, no one would upgrade every six months if they knew that disruptive damage or upheaval might be caused. While I may do a clean installation at some point, that is well down the priority list right now.

Are ten seconds enough?

Fasthosts, the hosting provider for what you find here, has, in their wisdom, decided to limit the execution time for ASP scripts to 15 seconds and 10 seconds for any others. I haven't used Perl sufficiently in this shared hosting set up to determine how that is affected. In contrast, I can share my experiences on the PHP side and you may have noticed occasional glitches. They have also disabled the set_time_limit PHP function, so you cannot easily address the matter yourself where you need to do it. You almost get the feeling that they don't trust the abilities, actions and oversight of their users. Personally, I reckon that the ten-second limit is too short and that something of the order of 20 or 30 seconds would be better. If it all gets too restrictive, I suppose that there are other providers, though I think that I would avoid resellers after a previous less than glorious experience. There's the dedicated server option too if I was feeling flush, not so likely given the economic times in which we live.

Self-hosted web analytics tracking

It amazes me now to think how little tracking I used to do on my various web "experiments" only a few short years ago. However, there was a time when a mere web counter, perhaps displayed on web pages themselves, was enough to yield some level of satisfaction, or dissatisfaction in many a case. Things have come a long way since then, and we now seem to have analytics packages all around us. In fact, we don't even have to dig into our pockets to get our hands on the means to peruse this sort of information, either.

At this point, I need to admit that I am known to make use of a few simultaneously but thoughts about reducing their number are coming to mind, but there'll be more on that later. Given that this site is hosted using WordPress software, it should come as no surprise that Automattic's own plugin has been set into action to see how things are going. The main focus is on the total number of visits by day, week and month, with a breakdown showing what pages are doing well, together with an indication of how people came to the site and what links they followed while there. Don't go expecting details of your visitors like the software that they are using and the country where they are accessing the site with this minimalist option and satisfaction should head your way.

There is next to no way of discussing the subject of website analytics without mentioning Google's comprehensive offering in the area. You have to admit that it's comprehensive, with perhaps the only bugbear being the lack of live tracking. That need has been addressed very effectively by Woopra, even if its WordPress plugin will not work with IE6. Otherwise, you need the desktop application (being written in Java, it's a cross-platform affair and I have had it going in both Windows and Linux) but that works well too. Apart maybe from the lack of campaigns, Woopra supplies as good as all the information that its main competitor provides. It certainly does what I would need from it.

However, while they can be free as in beer, there are some costs associated with using external services like Google Analytics and Woopra. Their means of tracking your web pages for you is by executing a piece of JavaScript that needs to be added to every page. If you have everything set to use a common header or footer page, that shouldn't be too laborious, especially when there are plugins for publishing platforms like WordPress too. This way of working means that if anyone has JavaScript disabled or decides not to enable JavaScript for the requisite hosts while using the NoScript extension with Firefox, then your numbers are scuppered. Saying that, the same concerns probably any JavaScript code that you may want to execute, but there's another cost again: the calls to external websites can, even with the best attention in the world, slow down the loading of your own pages. When you add in latency caused by servers having to communicate across the web, it is not all about executing JavaScript code.

A self-hosted analytics package would avoid the latter, and I found one recently through Lifehacker: Piwik, formerly known as PHPMyVisites. Usefully, it turns out that it does next to everything that Google Analytics does. While I'd prefer that it used PHP for this, JavaScript is its means of tracking web pages too. Nevertheless, page loading is still faster than with Google Analytics and/or Woopra and Firefox/NoScript users would only have to allow JavaScript for one site too. If you have had experience with installing PHP/MySQL-powered publishing platforms like WordPress, Textpattern and such like, then putting Piwik in place is no ordeal. Though, you may find yourself changing folder access, uploading of the required files, the specification of database credentials and adding an administration user is all fairly standard stuff. After all that, I have the thing tracking this edifice as well as my outdoor activities (hillwalking/cycling/photography) web presence and I cannot say that I have any complaints, so we'll see how it goes from here.

A new feature request for Textpattern?

Having been doing some updates to articles in A Wanderer's Miscellany, an idea that makes life easier when working in Textpattern with old articles has come to mind. Currently, there is no way to navigate through pages in the administration area other than using the search or previous/next functionality. Thus, I have started thinking that being able to subset articles by section or category using dropdown menus would be a good way forward.

A search for a suitable plugin yielded nothing of immediate use (amazingly, no one has given it a go thus far); hence the thinking regarding a new feature request. Because there is a place on the Txp support forum for exactly this kind of thing, I am in the throes of plucking up the courage to go for it. Apparently, some code cutting of my own would grease the wheels for the progression of any such thing; a lack of confidence in that area could reduce my input to a bare feature request. While moving to an alternative platform might be an alternative proposition, I see little reason in doing so when what I have otherwise works well for what I want it to do. That Textpattern feature request might just come into being...

/sbin/mount.vboxsf: mounting failed with the error: Protocol error

These days, my virtualisation needs are being well served by VirtualBox 2.2. Though it may be the closed source variant, I have no complaints about it. Along with a number of Windows VM's, I also have one running Ubuntu 9.04 and, for the first time, I seem to have VirtualBox's Guest Additions playing with a Linux guest as they should. Even the Shared Folders functionality is working.

However, I did get one problem when I tried out the last feature for the first time. The procedure is to issue a command like the following in a terminal session after creating the requisite directory in the file system and adding a host directory as a shared folder:

sudo mount -t vboxsf Music /mnt/host_music/

Above, Music is the name of the folder in the VirtualBox manager and /mnt/host_music in the directory in the guest file system. However, this returned the message at the head of this post at that first attempt:

/sbin/mount.vboxsf: mounting failed with the error: Protocol error

The solution thankfully turns out to be an easy one: reinstalling the Guest Additions, which certainly did the trick for me. The cause would appear to have been an update to Ubuntu, and 9.04 is understandably in a state of flux at the moment (I suspect kernel upgrades because of my previous experiences). Regardless of this, it is good to know that it's a problem with a simple fix, and I am seeing the niceties of a larger virtual screen system together with automatic grabbing and releasing of the mouse cursor too. While there may be a chance to explore the availability of these sorts of features to other Linux guests, I have other things that I should be doing and there's sunshine outside to be enjoyed.

On keyboards

While there cannot be too many Linux users who go out and partner a Microsoft keyboard with their system, my recent cable-induced mishap has resulted in exactly that outcome. Keyboards are such standard items that it is not so possible to generate any excitement about them, apart from RSI-related concerns. While I wasn't about to go for something cheap and nasty that would do me an injury, going for something too elaborate wasn't part of the plan either, even if examples of that ilk from Microsoft and Logitech were sorely tempting.

Shopping in a bricks and mortar store, like I was, has its pluses and its minuses. The main plus points are that you see and feel what you are buying, with the main drawback being that the selection on offer isn't likely to be as extensive as you'd find on the web, even if I was in a superstore. Despite the latter, there was still a good deal available. Though there were PS/2 keyboards for anyone needing them, USB ones seemed to be the main offer, with wireless examples showcased too. Strangely, the latter were only available as kits with mice included, further adding to the cost of an already none too cheap item. The result was that I wasn't lured away from the wired option.

While I didn't emerge with what would have been my first choice because that was out of stock, that's not to say that what I have doesn't do the job for me. The key action is soft and cushioned, which is a change from that to which I am accustomed; some keyboards feel like they belong on a laptop, but not this one. There are other bells and whistles too, with a surprising number of them working. The calculator and email buttons number among these along with the play/pause, back and forward ones for a media player; I am not so convinced about the volume controls though an on-screen indicator does pop up. You'd expect a Microsoft item to be more Windows specific than others, yet mine works as well as anything else in the Ubuntu world and I have no reason to suspect that other Linux distros would spurn it either. Keyboards tend to be one of those "buy-it-and-forget-it" items, and the new arrival should be no different.

A very silly mishap

Last night, something idiotic happened to me: I tripped up in my main PC's cables and brought the behemoth crashing about the place. There was some resulting damage, with the keyboard PS/2 socket being put out of action and a busted USB port and mouse. When this happens, thoughts take on the form of a runaway train and the prospect of acquiring a new motherboard and assorted expensive paraphernalia trot into your mind; there are other things that more need my cash. Of course, the last time to be making such big decisions on computer components is when a mental maelstrom has descended upon you.

Eventually, I got myself away from the brink and lateral thinking began to take over. What helped was that most of the system is unaffected, enabling me to write this post with it. While a spare will work for now, a new ergonomic mouse is on order, cheaper alternatives to the keyboard conundrum have come into play. If PS/2 wasn't an option, then USB remains one, and that was the line of attack that was taken.

It involved a visit to the nearest branch of PC World after work, from where I came away with a new USB hub and a USB-compatible keyboard for less than the price of a new AM2+ Gigabyte motherboard that would have served my needs. Though an otherwise functional Trust keyboard may have been retired, that was a less expensive option than a full PC rebuild, which I may still need to do, albeit with far less immediacy than what flashed before my eyes within the last 24 hours. In fact, acquiring some cable ties should be higher on the acquisition wish list to avoid cable-induced tumbles in the future. It really does pay to be able to step back and see things from a wider perspective.

Ubuntu upgrades: do a clean installation or use Update Manager?

Part of some recent "fooling" brought on by the investigation of what turned out to be a duff DVD writer was a fresh installation of Ubuntu 8.10 on my main home PC. It might have brought on a certain amount of upheaval, but it was nowhere near as severe as that following the same sort of thing with a Windows system. While a few hours was all that was needed, whether it is better to perform just an upgrade every time a new Ubuntu release is unleashed on the world or to go for a complete virgin installation instead. With Ubuntu 9.04 in the offing, that question takes on a more immediate significance than it otherwise might do.

Various tricks make the whole reinstallation idea more palatable. For instance, many years of Windows usage have taught me the benefits of separating system and user files. The result is that my home directory lives on a different disk to my operating system files. Add to that the experience of being able to reuse that home drive across different Linux distros, and even swapping from one distro to another becomes feasible. From various changes to my secondary machine, I can vouch that this works for Ubuntu, Fedora and Debian; the latter is what currently powers the said PC. Though you might have to use superuser powers to attend to ownership and access issues, the portability is certainly there, and it applies to anything kept on other disks too.

Naturally, there's always the possibility of losing programs that you have had installed, but losing the clutter can be liberating too. However, assembling a script made up of one or more apt-get install commands can allow you to get many things back at a stroke. For example, I have a test web server (Apache/MySQL/PHP/Perl) set up, so this would be how I'd get everything back in place before beginning further configuration. It might be no bad idea to back up your collection of software sources, either; I have yet to add all the ones that I have been using back into Synaptic. Then there are closed source packages such as VirtualBox (yes, I know that there is an open-source edition) and Adobe Reader. After reinstating the former, all my virtual machines were available for me to use again, without further ado. Restoring the latter allowed me to grab version 9.1 (probably more secure anyway) and it inveigles itself into Firefox now too so the number of times that I need to go through the download shuffle before seeing the contents of a PDF are much reduced, though not eliminated by the Windows-like ability to see a PDF loaded in a browser tab. Moving from software to hardware for a moment, it looks like any bespoke actions such as my activating an Epson Perfection 4490 Photo scanner need to be repeated, but that was all that I had to do. Getting things back into order is not so bad, even if you have to allow a modicum of time for this.

What I have discussed so far are what might be categorised as the common or garden aspects of a clean installation, yet I have seen some behaviours that make me wonder if the usual Ubuntu upgrade path is sufficiently complete in its refresh of your system. The counterpoint to all of this is that I may not have been looking for some of these things before now. That may apply to my noticing that DSLR support seems to be better with my Canon and Pentax cameras both being picked up and mounted for me as soon as they are connected to a PC, the caveat being that they are themselves powered on for this to happen. Another surprise that may be new is that the BBC iPlayer's Listen Again works without further work from the user, a very useful development. It obviously wasn't that way before I carried out the invasive means. My previous tweaking might have prevented the in situ upgrade from doing its thing, but I do see the point of not upsetting people's systems with an overly aggressive update process, even if it means that some advances do not make themselves known.

So what's my answer regarding which way to go once Ubuntu Jaunty Jackalope appears? For the sake of avoiding initial disruption, I'd be inclined to go down the Update Manager route first, while reserving the right to do a fresh installation later on. All in all, I am left with the gut feeling is that the jury is still out on this one.

AND & OR, a cautionary tale

The inspiration for this post is a situation where having the string "OR" or "AND" as an input to a piece of SAS Macro code, breaking a program that I had written. Here is a simplified example of what I was doing:

%macro test;
    %let doms=GE GT NE LT LE AND OR;
    %let lv_count=1;
    %do %while (%scan(&doms,&lv_count,' ') ne );
        %put &lv_count;
        %let lv_count=%eval(&lv_count+1);
    %end;
%mend test;

%test;

The loop proceeds well until the string "AND" is met and "OR" has the same effect. The result is the following message appears in the log:

ERROR: A character operand was found in the %EVAL function or %IF condition where a numeric operand is required. The condition was: %scan(&doms,&lv_count,' ') ne
ERROR: The condition in the %DO %WHILE loop, , yielded an invalid or missing value, . The macro will stop executing.
ERROR: The macro TEST will stop executing.

Both AND & OR (case doesn't matter, but I am sticking with upper case for sake of clarity) seem to be reserved words in a macro DO WHILE loop, while equality mnemonics like GE cause no problem. Perhaps, the fact that and equality operator is already in the expression helps. Regardless, the fix is simple:

%macro test;
    %let doms=GE GT NE LT LE AND OR;
    %let lv_count=1;
    %do %while ("%scan(&doms,&lv_count,' ')" ne "");
        %put &lv_count;
        %let lv_count=%eval(&lv_count+1);
    %end;
%mend test;

%test;

Now none of the strings extracted from the macro variable &DOMS will appear as bare words and confuse the SAS Macro processor, but you do have to make sure that you are testing for the null string ("" or '') or you'll send your program into an infinite loop, always a potential problem with DO WHILE loops so they need to be used with care. All in all, an odd-looking message gets an easy solution without recourse to macro quoting functions like %NRSTR or %SUPERQ.

No autofocus?

Recently, I recently treated myself to a Sigma 18-125 mm f/3.8-5.6 DC HSM zoom lens for my Pentax K10D. There was a wait for the item to appear, only then for me to find that the lens' autofocus facility wasn't compatible with the body when it arrived. Standard wisdom would have it that I sent the thing back and ask for a replacement or a refund.

Perhaps inexplicably, I did neither. In fact, I came to the conclusion, that since I make photos of landscapes anyway, that been slowed down by the lack of autofocus was no bad thing except perhaps when appealing light makes fleeting appearances. While it is true to say that a used Pentax manual focus lens would have been cheaper, I did what I did.

The camera's autofocus indicator still works and the 18-55 mm zoom that came with the camera wasn't impressive anyway, so taking matters into my own hands was something that happened a lot. Now, I have better quality glass in front of the sensor and with a metal mount and longer range too. The lens comes with a petal hood too, though I keep that for when I really need it rather than keeping it on the lens and stopping myself focussing the thing.

Speaking of zooming and focussing, the controls work well and smoothly without being at all loose. The AF setting gets used to lock the focus and the zoom can be locked at the wide end so that the lens doesn't get into the habit of zooming under the influence of gravity, not a bad thing. For future lens purchases, I might be more inclined to ask about compatibility next time around (I may have been spoiled by the Canons that I used to use) but I remain content for now.

All in all, it feels like a quality item, so it's a pity that Pentax saw fit to make the changes that they made, or that Sigma didn't seem to have kept up with them. Saying that, my photographic subjects usually don't run off so being slowed down is no bad thing at all, especially if it makes me create better photos.