Change the zsh heading to unix.

unix/where-are-the-binaries.md

@@ -0,0 +1,21 @@
+# Where Are The Binaries?
+
+When I want to know where an executable is, I use `which` like so:
+
+```
+$ which rails
+/Users/jbranchaud/.gem/ruby/2.1.4/bin/rails
+```
+
+That is the rails binary on my path that will be used if I enter a rails command.
+
+However, with something like rails, there may be multiple versions on your
+path. If you want to know where all of them are, you can use `where`, like
+so:
+
+```
+$ where rails
+/Users/jbranchaud/.gem/ruby/2.1.4/bin/rails
+/Users/jbranchaud/.rubies/2.1.4/bin/rails
+/usr/bin/rails
+```