On mac zipalign command not found

Let me start by saying that this question has been asked a couple of times, but the solutions that have worked for them have not worked for me so my problem is slightly different.

I am building my first app using ionic, and I am following along with this tutorial. I have finished the tutorial except I am stuck on this step:

zipalign -v 4 HelloWorld-release-unsigned.apk HelloWorld.apk

For me, I am using a different folder path convention and app name, so my command looks like this:

./zipalign -v 4 /Users/jcorser/todo/platforms/android/ant-build/todo-release-unsigned.apk todo.apk

I have tried this both with and without the ./ but the result is always one of these:

-bash: ./zipalign: No such file or directory

OR

-bash: zipalign: command not found

I have build tools rev 20 installed in Eclipse/android studio. However, operating from the command line, it seems as though the build tools are not installed.

Any idea why this might be?