I needed to add some captcha foo to a Perl CGI I was writing, so I took a look at the Authen::Captcha module, which looked pretty simple, but, wait… requires GD, which requires the GD Library, which requires… you get the picture.

Luckily I found a guide titled: Compiling GD on Mac OS X HOWTO, which I followed, and which failed for me. (I did get newer versions of zlib and FreeType, but the rest matched up.) Once again, GD got me. After repeated attempts and failures (it was a long day) I finally realized that libtool was tripping me up. See, there is this bit:

% cd ../gd-2.0.33
% ln -s `which glibtool` ./libtool
% ./configure

But after running the ./configure my symlink to libtool had been replaced by a file named libtool. This was easily fixed by running ln -s `which glibtool` ./libtool again after running ./configure like so:

% cd ../gd-2.0.33
% ln -s `which glibtool` ./libtool
% ./configure
% ln -s `which glibtool` ./libtool

I am running Mac OS X 10.3.9, and I’m not sure what else is different, I’m just documenting what I had to do. Anyway, I’ve now got GD installed, as well as Authen::Captcha and I can now attempt to determine if someome is a robot or a real human being. (Or at the least, discriminate against those with accessibility issues. Apologies to Bender…)

(Thanks to Matías Giovannini for writing the guide.)