How to return a specific exit code from a Mix Task?

Question

I'm writing a Mix Task that is supposed to be as part of CI and should stop the build process if it fails, which is normally done using exit codes , where 0 code denotes success and non-0 an error. I would want to be able to return an arbitrary exit code to signal different types of failures.

How would I do it in a Mix.Task ? The documentation for the run/1 callback doesn't say anything about it.

Answer 1

Use exit/1 . For example putting exit({:shutdown, 15}) inside your mix task will result in the following:

$ mix compile && mix custom.task
$ echo $?
15