Category Archives: Geeky

Posts about geeky stuff: new technology, cool programs, accounts of computer problems I’ve solved, etc

Au Revoir, Internet Café

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On previous trips, publishing a blog post or keeping in touch with home meant allocating some time to locate a reasonably priced Internet café and writing while watching a ticking timer. For this trip however I have been able to write at leisure in spare moments on my phone thanks to the availability of pre-pay GSM sim cards with data allowances.

In Australia, amaysim have been particularly good value although I only discovered their existence after considerable Internet research. A $10 purchase in-store sim card purchase gave us 1GB of data valid for 30 days plus $10 of pre-pay phone credit (90 day expiry). The network is provided by Optus, in common with most of the cheap prepaid sim offerings. There were a couple of issues though which I document here for future travellers.

  • We bought the sim card in a Seven-Eleven. The website claims you can buy them in post offices but the one we tried did not stock it so the availability might not be great. The same pack contains a sim that may be used with either the normal or micro sim formats.
  • Online activation claimed to work but actually failed because of my non-Australian address and credit card. You must call them to get your $10 purchase converted to a data plan. I have not tried to top up the credit yet but it makes me think that credit card top ups might be difficult. Buying vouchers works around this, but see the note above on availability.
  • The sim we bought has been used in multiple devices. I can report that despite rumours to the contrary, a sync with iTunes is not required to change the provider on an iPhone (at least on iOS5). However some devices could not access the Internet until the APN had been set manually to “Internet”, others just worked, for reasons I have yet to figure out.

Using the Terminal to restore from a Time Machine backup

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I recently had to restore some Application Data from a Time Machine backup and since Finder in OS X 10.7 (Lion) now hides the Library folder in your home directory I thought it easiest to just cp the files from the mounted volume to the right place. It turned out that this it was not as straightforward as that because the restored files retained the read only permissions that prevent you from modifying a backup.

The ACL does not appear in the Finder, but can be seen using ls -le:

0: group:everyone deny write,delete,append,writeattr,writeextattr,chown

and also metadata: com.apple.metadata:_kTimeMachineNewestSnapshot 50

The ACL can be removed using chmod -a #n filename where n is replaced by the number at the front of the ACL description (0 in this case). Applying it recursively is possible but potentially dangerous1 unless you know this is the only ACL applied to the files in the directory. The metadata can be removed using xattr, like this:
xattr -d com.apple.metadata filename


  1. and consequently left as an exercise to the reader [back]

Postfix and SMTP AUTH on OS X Lion

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The standard instructions for configuring postfix to use authenticated SMTP to use authentication when forwarding to a relay host did initially work for me on OS X Lion so for future searchers here is how I made it work.

  1. Create the file /etc/postfix/sasl_passwd as described in the standard docs, i.e. at least one line containing:
    server username:password
    and set the permissions using sudo chmod 600 /etc/postfix/sasl_passwd.
  2. Make the db version used by postfix: sudo postmap /etc/postfix/sasl_passwd (the new file will inherit the permissions of the original file).
  3. If you have upgraded from a previous version of OS X, particularly if you modified your postfix configs, follow the advice in the section below before continuing.
  4. To tell postfix to use authenticated SMTP, add the following lines to /etc/postfix/main.cf:

    mydomain = <<your.mail.domain>>
    mydomain_fallback = localhost
    smtp_sasl_auth_enable = yes
    smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd

    If your domain’s MX records do not specify your relayhost then you must also set the relayhost line.
  5. postfix on OS X runs “on demand” so there is no need to instruct it to reload its configuration. The log file is in the standard UNIX location, /var/log/mail.log.

Upgrading from Snow Leopard

I had previously had this postfix setup working under Snow Leopard, and the upgrade process appeared to have preserved my configuration settings so I was surprised to see that after upgrading to Lion, my smarthost was not accepting mail.

Examining the files in /etc/postfix I noticed that in addition to my customised main.cf there was also a file called main.cf.default which was modified the date I had upgraded to Lion. Comparing the two files showed a number of subtle differences but after being unable to determine why postfix was not authenticating to my upstream server, I decided to copy it over my customised main.cf and re-apply my changes.

Having done this, the mailq command gave me the following error:
postfix[17922]: fatal: bad string length 0 < 1: setgid_group =
Setting setgid_group = _postdrop in main.cf fixed that but then I hit another error:
fatal: file /etc/postfix/main.cf: parameter mail_owner: user postfix has same user ID as _postfix
Resolving this required me to change the value of mail_owner from postfix to _postfix but I don’t know if this is a bug in Apple’s supplied main.cf or an artefact of my user and group information evolving from a 10.6 install to 10.7.

iPhone Buying Advice

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A number of people have recently asked my advice on buying an iPhone so I thought it worth writing up my current thoughts.

iPhone or Android (Samsung/HTC)

At the moment any phone marketed as an “iPhone competitor” is running Google’s Android software. I have not personally used an Android phone beyond a quick demo of friends’ devices but a survey of articles suggest that latest software has a comparable set of features to the iPhone, and every Apple-hater will quickly tell you that Android is better because it can do X, Y and/or Z, which Apple are too arrogant or controlling to allow. If you are someone who understands what feature X, Y or Z is and feel you need it, then you should get an Android phone. Everyone else should read this quote from a review of the newly released iPad-clone from people that make Blackberries:

“Browsing on the PlayBook ends up feeling very much like an Android device – perfectly usable, but not up to iOS [i.e. iPhone] standards.”

Whether this is something you find annoying enough to justify a more expensive iPhone over an Android device can to some extend be determined by spending some time with a friend’s phone or an in-store demo, so I highly recommend doing this. Another frequent complaint about Android phones is that the battery life is worse than that of an iPhone1, especially those models with the larger screens.

One of the major features of Android is the ability to install apps which have not been vetted by Apple. However it is highly unlikely that an average user would want to install an application that was banned by Apple so that advantage is moot. There is also an argument that since the iPhone+iPod+iPad2 platform is currently making developers a lot of money, and Android upgrades must be blessed by the phone manufacturer3 after being released by Google, iPhone owners are likely to get the latest and greatest apps before Android owners, and certainly no later.

It is natural that older Android phones which do not have all the latest iPhone features are practically being given away by the phone companies (so too the two-year old iPhone 3GS) but recently released Android phones are also considerably cheaper than iPhone 4s. For example today on orange.co.uk a £35 per month contract for 24 months will get you the recently released HTC Desire S for £0, while an iPhone4 costs £119 on the same monthly tariff. I don’t think I can tell you whether it is worth you paying that extra £119, only hands-on demonstration and experimentation with a phone will tell you whether you think the phone will be good enough, the right apps available for what you want, and the battery life long enough.

Should I buy an iPhone 4 now or wait for iPhone 5?

While Apple are highly secretive about their product plans, it is widely believed that Apple have unofficially set media expectations that unlike previous years they will not be announcing a new device at their annual developer conference in June. There is no reliable information as to when a new iPhone might be released but the smart money is on a September announcement alongside this year’s iPod line-up.

Historically, supplies of new models has been extremely limited for the first few months so waiting until September realistically means waiting another month or two after the release date, and expect to pay at least the current cost of an iPhone 4. At the moment (May 2011), there is the possibility you may find a carrier able to offer some sort of discount on an iPhone 4 which will easily give you 18 months of good service before an Autumn 2012 release of the next generation.

Do I need a screen protector for my iPhone?

No. The iPhone 4 screen is designed to be touched directly and manufactured to a high quality. Placing an additional layer of low quality plastic between you and the screen will impair its function. I can really recommend the InCase Snap case (~£10 on ebay.co.uk, or half that for a clear plastic knock off) which protects the back and has a raised ridge around the front preventing contact should the phone be placed face down on a surface. If you need to protect the screen while the phone is not in use (e.g. inside a hand bag or similar) then buy a case that has a cover you put over the screen when not in use, or store the phone in a sock when inside the handbag.


  1. 7 hours of talk time and 300 hours standby is claimed by Apple [back]
  2. a.k.a. “iOS” [back]
  3. This is significant since if an app requires the latest version of Android and your manufacturer has not blessed it yet then that app will not be available to you, even if it it is available on other Android phones. [back]

FreeviewHD PVR Review

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FreeviewHD has been broadcasting in our area for several months but since we almost never watch live television it seemed pointless to to buy a FreeviewHD (or DVB-T2 to use the technical name) receiver without some sort of recording capability. These have taken a surprisingly long time to reach the market but I noticed last weekend that the venerable John Lewis were selling a 500GB Digital Stream DHR8205U FreeviewHD hard-disk recorder and since the reviews on the web forums were broadly positive, made something of an impulse buy.

I quickly discovered that if the TV is not plugged in during boot then the box will flash “loading” at you forever but after that initial false start installation was smooth and the HD reception is an appreciable upgrade. The feature set appears comprehensive and although there is no option to repeat a recording daily or weekly, it can be instructed to record an entire series of programmes which is usually sufficient.

My biggest complaint is that the user interface is definitely quirky, which reminds you that this is definitely early-adopter territory. Most annoying is the remote control which has some of the most commonly used features (such as ‘pause’ and ‘library’) on tiny buttons which are laid out with no semblance of logical grouping. The listings guide is quite useable, although the ordering of the channel list is not customisable which means the three HD channels are 6 screens away from their non-HD equivalents. Pressing the large “OK” button during viewing brings up the list of channels with no programme information which seems redundant: on my previous PVR this button showed the current and next programmes. The screen showing the recorded programmes appears to have had so little attention that it might actually be an afterthought: recordings are laughably labelled simply as ProgrammeName_DDMMHHMM.trp. Fortunately there is at least a chance that the software issues might be fixed with the next software update scheduled for the end of June.

The user guide suffers from similar problems of poor readability including at least one circular reference (the effect of enabling “standby power-saving mode” is never explained). The packaging describes the product as “Manufactured in the UK” but DigitalStream itself seems to be a Korean company and the terminology used by the software is from a bizarre parallel universe: channels are called “services”, future recording “reservations” and the stored programmes library is “media”. Despite these foibles, so far I am a happy customer.

A Personal History of UNIX Tool Management on OS X

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When I first switched to Mac from Linux I used fink to provide the simple software installation (and removal!) to which I had become addicted while using Debian. In addition to being command line compatible, fink also shipped the software as binaries which on the relatively slow CPUs of the day meant the software was able to be used much more immediately than if it had to be compiled.

About three years ago, I noticed that the fink binary distribution no longer had all the packages I wanted to use. The website would indicate the package was available but actually it would be only available in source code form and my aging laptop did not have the CPU or disk space available to compile not just the package but all its dependencies. When I upgraded that old laptop, and compiling everything from source seemed feasible, I decided that the MacPorts project had more community activity and jumped ship.

MacPorts worked very well. The initial install took time, and worked the fan of my MacBook quite hard, but once the base packages were compiled, subsequent software installs and updates were mostly painless. MacPorts also made it vary easy to tweak installs using its variants mechanism. However MacPorts’ downfall, in my opinion, is that it is not content to be just a way of augmenting the existing UNIX tools on my Mac but that it wants to be a self-contained operating system itself. For example, in order to install the git-svn tool MacPorts was going to download, compile and install not only an older version of Perl than is shipped with 10.6 but also a second version of the subversion tool that Apple have already provided. I am sure this is a good way to deliver a powerful and stable system, but it felt like MacPorts was taking over.

I am not the first to think this since someone has developed homebrew. It has the explicit goals of playing nicely with the OS defaults and programming language specific distribution systems such as RubyGems, CPAN and PyPi. I am pleased to be report that homebrew was very quick to setup and install the few remaining UNIX packages to which I remain addicted. The installer makes the assertion that every user on your system should be in the staff group,1 but the script was very simple to modify and I have submitted my version back to the maintainer.

The one package where I do not find homebrew satisfactory is LaTeX. homebrew uses the TeX Live distribution rather than the tetex package I have used in the past. However TeX Live is a humungous 1GB download and some quick research showed that it was very much a kitchen sink package with many sub-packages that were completely unnecessary for me. Instead I highly recommend the 85MB download (234MB installed) BasicTeX package which has proved to be entirely adequate for my needs, even if it does have softie GUI installer!


  1. I noticed that on a fresh install of 10.6 no one is a member of the staff group. It appears that all Administrator users are members of the admin group though, and since it seems to only allow admins to change the machine’s homebrew install, I forked this gist and replaced all the instances of staff with admin. [back]

On Motion Pictures

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I have a fairly sizeable collection of video clips from our trip to New Zealand, which one day I hope to assemble into something which might be worthy of the term film.

My first observation is that while holiday photographs need a nominal amount of sorting and post-processing before being displayed, video is much more demanding of time, effort, and computing power. Having struggled to get to grips with previous incarnations, Apple’s iMovie 09 has been fantastic: arranging clips through drag and drop is very natural and when a “drop” is ambiguous it pops up a short menu of options. Cropping, rotating and reversing clips is simple and speedy (admittedly this is a borrowed MacBook Pro rather than my own wimpier and older MacBook). At first I was wary of the themes but the strong visual style makes it easy to decorate the film in an attractive way.

My second observation is that next time we capture videos there are some basic rules we can follow to make the post-processing a lot easier!

  • Set the scene with a strong opening shot. For example, when capturing a ferry crossing, start the clip with the shot of the ferry’s funnel instead of panning onto it at the end (the aforementioned “reverse clip” feature has rescued at least one such clip which ended where it should have started).
  • Keep the panoramas to a minimum: the vista may be beautiful but try to capture something a photograph cannot, such as the motion of waves lapping/pounding a shoreline.
  • Leading on from the previous point, sound is important. The camera records audio as well as video, so even if there is little or no action the sound can bring interest to a clip.

To thank you for reading this far, while I have not finished my masterpiece film of our entire three week trip, I did make a short trailer featuring just the footage from our dolphin encounter in Kaikoura.

Ubuntu Upgrade: 8.04 to 9.04

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Yesterday I upgraded my Ubuntu machine directly from Hardy Heron to Jaunty Jackalope (release candidate 1), in defiance of the release notes. I could not find any specific problems indicating what would happen if I broke the rules so I went ahead anyway and it worked fine—fortunately there is no Change Management Board in this flat!

Upon first boot it is not immediately obvious what is new in this release, although the new ‘Dust’ theme is so polished it feels like my desktop has received a heavy application of windolene, and it was nice to see that my widescreen monitor was now recognised automatically rather than requiring the installation of an additional package. Moving to Jaunty also brought an upgrade of my entire application set, including the latest version of Gnome Do which features an OS X-style dock.

Rarely is an upgrade without issues but this was a pretty good one:

  • The Gnome desktop sharing service (vino-server) now causes X to consume 60% of CPU time even when no one is connected. The only workaround is to turn off desktop sharing.
  • The new human-theme package conflicts with the Blubuntu theme packages. I just left this un-upgraded since I really like the blue theme.
  • Not so much an issue, but after three years of successive upgrades there was some junk that needed to be removed manually: php5 and emacs22 are now default/production (and you still need emacs-snapshot for anti-aliased fonts) so I removed all the php4 and emacs21 packages. There were also half a dozen old kernels that were too out of date to be any use.

Blogs: Conversation or Monologue?

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Back in February, the twitter-verse reverberated with a post describing a system for using twitter as a replacement for comments on blog posts. Regardless of the effectiveness or shortcomings of that particular system, I think the author explains very succinctly the failings of blog comments and the potential of using a social network to overcome them. Recently another blogger noted that when it comes to popular websites:

I’d rather hear what any of my friends says on any topic, rather than what people I don’t know say about a specific article.

Sites such as Disqus and Intense Debate also try to address these problems but populating yet another website with ‘friend’ information seems like duplication compared to using an existing network like Twitter, or Facebook.

Facebook recently released a very simple Comments Widget which I have installed below as a trial-replacement for traditional comments. To leave a comment, click ‘Connect with Facebook’ and authorise toobusyto.org.uk as a Facebook application, then leave your comment in the box. Regular comments are available below the Facebook Comment widget for people without Facebook accounts but since the Facebook widget can be customised to support anonymous comments, if the experiment is successful I eventually plan to turn that off. Let me know what you think!

PS – The ‘number of comments’ stat on the front page will be inaccurate due to the new system.
Comment counts should now (mostly) be accurate.

Using a Netgear DG834Gv3 as an ADSL modem

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Last week I treated myself to a new NAS device (cost: £££; good backups: priceless) which also has a built-in 802.11N wireless access point. Consequently I needed to find a way to make my Netgear DG834Gv3 act as a pure ADSL modem to avoid the headache of two layers of NAT.

While not documented/officially supported, the Netgear can be used as a pure modem (sometimes called “Bridge-only Mode” by other vendors) using a hidden link and selecting “modem-only” mode: http://192.168.0.1/setup.cgi?next_file=mode.htm

This was trivial to find using the leading search engine, but it does not work using the default settings in the UK—you must also change the ADSL multiplex method to “LLC” on the “ADSL Settings” page1. Having done this, connect the second wireless AP/router/computer to the Netgear via ethernet and configure it to connect to the Internet using PPPoE.


  1. Confusingly this is the opposite to the standard setting used when configuring UK ADSL which would normally be VC-based multiplexing [back]

iPhone Voicemail Setup Problems (& Solution)

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The first time you select the voicemail button your an iPhone, in typical Apple fashion, it offers to help you configure your voicemail. This was much nicer than the traditional voice prompts one normally has to navigate, but the final step (talking to the network) repeatedly failed for me. Google indicated that it might be necessary to manually activate the voicemail by calling 1750, but that did not work for me. O2 customer service suggested that turning the voicemail off then on again would help (1760 [send] then 1750 [send]) but the setup failed again.

The solution that eventually worked for me was to configure voicemail in the “old-fashioned” (“non-visual”?) manner by dialling 901 and then following the tedious voice prompts. Once this had completed, I retried the iPhone visual voicemail setup using the same PIN as I configured at the voice prompts, and it worked first time.

So is the iPhone any good?

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As revealed in my previous post, I recently purchased an iPhone. The reason for this is that the Internet stopped working on my old phone, and since I needed a new portable Internet device anyway and the web being the iPhone’s forté, it seemed like the best choice for my requirements.

But is it any good as a phone? The answer is undoubtedly yes, but it’s not “great”… yet, a few more software updates ought to fix that. Missing features that, upon reflection, I never used on my old phone include voice dialling (I’m sure voice recognition systems are not tested on west country accents!) and video calling. The one feature that is sorely missing is a character counter in the SMS application, a horrendous omission now there are call plans without unlimited text messaging. The other feature that people talk about is the keyboard which is a joy to use—last week’s Heathrow Express post was written and edited entirely on the iPhone.