How to explicitly fail a task in ruby rake?

Let's say I have a rakefile like this:

file 'file1' => some_dependencies do
  sh 'external tool I do not have control over, which sometimes fail to create the file'
  ???
end

task :default => 'file1' do
  puts "everything's OK"
end

Now if I put nothing in place of ???, I get the OK message, even if the external tool fails to generate开发者_StackOverflow社区 file. What is the proper way to informing rake, that 'file1' task has failed and it should abort (hopefully presenting a meaningful message - like which task did fail) - the only think I can think of now is raising an exception there, but that just doesn't seem right.

P.S The tool always returns 0 as exit code.

---

Use the raise or fail method as you would for any other Ruby script (fail is an alias for raise). This method takes a string or exception as an argument which is used as the error message displayed at termination of the script. This will also cause the script to return the value 1 to the calling shell. It is documented here and other places.

---

You can use abort("message") to gracefully fail rake task.

It will print message to stdout and exit with code 1.

Exit code 1 is a failure in Unix-like systems.

See Kernel#abort for details.