How can one detect if a github actions runner is running in ubuntu or windows-CodePudding

Is it possible to detect which OS a Github actions runner is using? For example, in node one can run process.platform to get the OS. Is there something analogous inside of Github actions?

CodePudding user response：

There is an environment variable $RUNNER_OS containing the operating system; you can specify the shell for a run: independent of the runner operating system, i.e., you can use Bash everywhere.

For example, this workflow

name: OS test

on:
  workflow_dispatch:

jobs:
  printos:
    name: Print OS name for each OS
    strategy:
      matrix:
        os:
          - ubuntu-20.04
          - windows-2022
          - macos-11
    runs-on: ${{ matrix.os }}
    steps:
      - name: Print OS name
        shell: bash
        run: |
          echo "$RUNNER_OS"

produces three jobs, with outputs Linux, Windows, and macOS, respectively.