Is there a way to define the shell to use for all steps?

For some work with and a action I am writing to setup conda, I need to run shells as 

- name: Bash
  shell: bash -l {0}
  run: ...

so that any /.bash_profile… etc … are picked up.

Is there a way to define this shell to use in a more global manner so that it does not need to be defined for every step?

Cheers

Sadly, there is not. If you dig a bit, you’ll find few old threads saying that suggestion has been added to internal tracker, but nothing more than that.