Exclusion using File Masks
Find in Path.. functionality to find a word across multiple files, file masks can be used to match certain types of files. For example, using *.rb will only look through Ruby files. On the other hand, if you want to exclude Ruby files instead, you can add an ! at the front (i.e. !*.rb).
Here are other useful examples/combinations:
all files excluding spec tests: !*spec.rb
all Ruby files excluding spec tests: *.rb,!*spec.rb