I was also trying to figure out how to use the shell option to run a powershell script. The doc shows the following definition:

jobs.<job_id>.steps.run.shell

So I tried to make a sub-property of run (which I don’t think is valid yml, but the editor doesn’t do any validation so it’s hard to tell):

name: CI
on:

push:

branches:

- master
jobs:

build:
runs-on: windows-2019

steps:
- uses: actions/checkout@v1
- name: Run a one-line script
  run: .\MyScripts\install.ps1
    shell: powershell

Which errored with:

yaml: line 17: mapping values are not allowed in this context

I gave up and just used powershell from the cmd command instead of trying to change the shell:

name: CI
on:

push:

branches:

- master
jobs:

build:
runs-on: windows-2019

steps:
- uses: actions/checkout@v1
- name: Run a one-line script
  run: powershell .\MyScripts\install.ps1

Hopefully some examples can be added to that page to show how to actually use the shell parameter

Try:

name: CI
on:

push:

branches:

- master
jobs:

build:
runs-on: windows-2019

steps:
- uses: actions/checkout@v1
- name: Run a one-line script
  run: .\MyScripts\install.ps1
  shell: powershell

Its working for me - https://github.com/damccorm/actions-playground/pull/9 - I think this is just a docs issue

cc @rachmari