which which?

I’m using locomotivecms for a project I’m working on, and it uses ImageMagick for resizing pictures on the fly. The standard instructions say to use the bitnami Ruby stack installer to get everything you need in a nice neat bundle.

That worked for me for a while, until I needed to update the version of ruby I’m using. So, I went through the long and painful process of uninstalling the ruby stack, installing each component individually, identifying and correcting a ton of minor problems, and finally squashed the last bug by writing this program.

Essentially, the command bundle exec wagon serve looks up the location of ImageMagick’s convert.exe program by invoking which convert, which only works on linux systems, or if you’re using a port like unxutils. So, once I got ruby working and was self-hosting my site for development, none of my resized images were showing up. The console showed this error message:

which: no convert in (...;C:\Program Files\ImageMagick-6.9.0-Q16;...)

So GNU which v2.4 for some reason can’t find convert.exe inside the ImageMagick install. After playing with it, I found that which convert.exe worked, but which convert didn’t. Very lame.

♪ Cause I still haven’t found what I’m looking for… ♪

The next couple hours were an adventure in dirty hacks. First I tried removing GNU which off the path, and using MSYS which. MSYS which is a shell script, so I made a batch file wrapper to invoke it using MSYS sh. That could find the file, but it resulted in a unix-style path: /c/Program Files/ImageMagick-6.9.0-Q16/convert. Since wagon is feeding this path directly into a cmd /c invocation, it wasn’t good enough.

After unsuccessfully playing with writing a batch script to invoke where, I decided to write a clone of which in go. This accomplished two objectives: fix my locomotivecms install, and learn go. The requirements are very simple, the command which convert should return a string that can be passed to cmd /c to invoke ImageMagick’s convert.exe.

It took me 2-3 hours to do, but here is my first complete go program! https://github.com/gburgett/which