Rake Only Lists Tasks With Descriptions

Rake describes the -T flag as

Display the tasks (matching optional PATTERN) with descriptions, then exit.

And rake -T does just exactly that. It lists all the tasks with descriptions. Any rake task that you define without a desc will not be included.

Consider the following rake task definitions

desc 'foobar does this and that'
task :foobar do
  puts 'this and that'
end

task :foobaz do
  puts 'not so much'
end

This is what I get when listing the rake tasks filtered by foo

$ rake -T foo
rake foobar  # foobar does this and that

The foobar task (which has a description) is listed, but foobaz is not.

A hack of sorts to get around this is to use the -P flag which will end up listing all tasks even if they do not have a description (rake -P | grep 'foo').