my nest somewhere in GitHub's forest

Installing Xcode 4

After the recent upgrade to OS X Lion, I installed the latest release of Xcode (version 4.2.1 when I’m writing these words).

I used to download big disk image files from Apple Developer site, but this time, given that I’m not a member of any of Apple Developer Programs, I had to turn to the App Store… which downloaded the Install Confident enough, I started it, but the interface was too simple and sleek, with no way to tweak the installation process.

Digging a bit into the application bundle, it turned out that the old interface is still there, because the new installer just wrap the meta package and the product packages, so opening Xcode.mpkg, hidden into the Contents/Resources folder, brought up the usual interface which allows one to deselect some optional components.

Doing it from the terminal is actually much, much easier:

Moving a Time Machine Disk

Recently I had to upgrade to OS X Lion; given that I didn’t want to lose all the backups performed since my first days in OS X’s world, back in April 2008, I studied for a while a plan that allowed me to move a Time Machine disk across.

I know, I know: had I used Migration Assistant, there probably would have been no issues at all, but I moved things manually and took the time to clean up a bit some things. Anyway, moving such a disk is not difficult, really, it just takes a lot of time.


Before going on, however, maybe it’s better to clarify what I mean with “move”: I don’t refer to moving the machine directory from a smaller disk to a larger one (another easy operation: fire up Disk Utility and “restore” the smaller disk onto the larger one; you’ll end up with a “clone”, just bigger), I mean using the same machine directory with a differt machine, keeping the history and list of every backup already performed.

With Lion, there’s no need to fiddle with ACLs, extended attributes, MAC addresses and so on, thanks to the addition of tmutil; nevertheless, there will certainly be some troubles due to “insufficient” Spotlight’s indexes that will slow down backups if we don’t improve the situation (would you like if your backups lasted hours and you logs filled up with tons of Waiting for index to be ready (100)? No, I guess the answer is no).

Please, note that the following operations are potentially destructive, will prevent you from using again the backup disk with the old Mac, should not be performed if you’re not comfortable with the terminal and you don’t know what you’re doing. Moreover, in no event I shall be liable for any claim, damages or other liability. If you accept that risks are all yours, go on.


Let’s assume the following:

  • backup disk is called MyBackupDisk;
  • the Mac is called MyMac;
  • old Mac’s disk is called MyOldDisk.

So, without further ado:

  • turn off automatic backups (sudo tmutil disable);
  • connect the backup disk;
  • associate that disk with the Mac:
  • “reset” Spotlight’s indexes:
  • reindexing everything will take a lot of time, so you’ll have to wait patiently;
  • turn on automatic backups (sudo tmutil enable).

With brand new Spotlight’s indexes, Time Machine won’t have any problem to quickly backup your machine and all your old backups will be at your disposal.

Before ending, let me repeat: I have personally executed this procedure successfully, but it involves direct manipulation of your backups, so take your time to think about it before doing anything and be ready to take the consequences.

Picking Out Languages

I like static site generators: you need less resources to host your sites (even one of the almost useless EC2’s micro instances could be enough) and you can move them around more easily, even to other hosting services with very little fuss. Obviously, there are some inherent limitations, but some of them can be overcome easily by using external services, while others cannot be reliably defeated without help from the hosting platform.

An example which intrigued me recently: your site is translated in multiple languages and the users should be offered the “best” language.

What’s the “best” language? The official one spoken in the users’ countries or the system/browser language chosen by the users themselves?

In the first case, we should try to locate the users via some geolocation mechanism, but is it really the right way to guess the users’ languages? I mean, I live in Italy but for many years (and to some extent still these days) I haven’t used Italian as the primary language of my computers; a good friend of mine lives, at the moment, in a German-speaking country but I don’t think he’s using his system in German. No, I think geolocation should not be used to guess the users’ languages, but it can be useful if your site’s contents are more tailored to countries than languages.

What’s left? Asking the users/browsers. Enter the Accept-Language header.

Good browsers send requests with the Accept-Language header listing the preferred languages, each with an optional priority values, and usually ordered according to these priorities. Users can modify this list at system or browser level (setting the system language is usually enough), so assuming it reflects the languages our users would like to use is a safer bet, I think.

Forgetting (unportable? unreliable? impossible?) attempts to get this list via JavaScript, we must rely on the web server because it’s the only “active” part of our system. My preferred one is Nginx, at the moment; to have it parse the Accept-Language header we must use a third-party module, the Nginx Accept Language module (adding it is not really difficult and thanks to a smart guy I’ve learnt a couple of ways to automate the process).

The module’s doc already shows how to use the detected language value but here are my two cents:

In this way, every generic, “language-less” request will have a chance to lead users to a translated resource, but, assuming internal links are correctly namespaced, requests for already translated resources won’t force another language upon our users.

So, with a little help from the web server we can try to guess users’ preferred languages; we’re left with problems like how to organize the static site with minimal duplication and how to reduce the effort to keep the different languages in sync, but here Nginx cannot help us :-)

Stripping Exif Tags

I’ve recently started to use nanoc more often; I still like Jekyll, but it’s better to have more options in one’s toolbox and I’ll probably try other generator in the not so distant future.

Just today’s has been released version 3.2, which allows you to create custom commands! Super! Anyway, for the kind of “transformation” I needed, the well-known filter mechanism was the essential ingredient and was already available about a month ago, when I needed it :-)

I had an image gallery and wanted to remove every Exif tag from every photo. It’s a menial task when you have the right tool, i.e. the wonderful ExifTool, but first of all I didn’t want to do it manually and then I wanted to keep the original files untouched.

So, here’s what I came up with:

It’s a really, really simple filter… I’d dare to say it’s rather stupid :-) and its use is a no-brainer.

First Month

Today marks the first month into my new job at Shopify. Shopify's bag

What a month! Not a single day’s been tiresome: while externally Shopify could seem a slowly moving entity, behind the scene there’s a constant flux of improvements, fixes and tweaks to the facing application and a growing army of internal projects and tools.

It’s a wonderful business to work for.

I’ve been so lucky that Alex, Dale and Cody decided to hire me on and I’m so happy to work with so many bright people that during the last month I woke up at least a couple of times thinking to have dreamed up everything :-D

New cucumber-rails: adios Webrat!

So, cucumber-rails 0.5.0 has been released today and among the other changes there’s the final blow to Webrat. Now, the tortuosities I wrote about some months ago are not needed anymore… but may a lightning strike me right now if I’ve been able to use it right out of the box!

To fix the all too frequent “undefined method `visit’” error message I had to add a couple of require statements:

Dropped that file in the support directory and everything turned green.