Using environment variables

GitHub sets default environment variables for each GitHub Actions workflow run, but you can also set custom environment variables in your workflow file.

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In this article

About environment variables

GitHub sets default environment variables that are available to every step in a workflow run. Environment variables are case-sensitive. Commands run in actions or steps can create, read, and modify environment variables.

To set custom environment variables, you need to specify the variables in the workflow file. You can define environment variables for a step, job, or entire workflow using the jobs.<job_id>.steps.env, jobs.<job_id>.env, and env keywords. For more information, see "Workflow syntax for GitHub."

steps:
  - name: Hello world
    run: echo Hello world $FIRST_NAME $middle_name $Last_Name!
    env:
      FIRST_NAME: Mona
      middle_name: The
      Last_Name: Octocat

Default environment variables

We strongly recommend that actions use environment variables to access the filesystem rather than using hardcoded file paths. GitHub sets environment variables for actions to use in all virtual environments.

Environment variable Description
HOME The path to the GitHub home directory used to store user data. For example, /github/home.
GITHUB_WORKFLOW The name of the workflow.
GITHUB_ACTION The unique identifier (id) of the action.
GITHUB_ACTIONS Always set to true when GitHub Actions is running the workflow. You can use this variable to differentiate when tests are being run locally or by GitHub Actions.
GITHUB_ACTOR The name of the person or app that initiated the workflow. For example, octocat.
GITHUB_REPOSITORY The owner and repository name. For example, octocat/Hello-World.
GITHUB_EVENT_NAME The name of the webhook event that triggered the workflow.
GITHUB_EVENT_PATH The path of the file with the complete webhook event payload. For example, /github/workflow/event.json.
GITHUB_WORKSPACE The GitHub workspace directory path. The workspace directory contains a subdirectory with a copy of your repository if your workflow uses the actions/checkout action. If you don't use the actions/checkout action, the directory will be empty. For example, /home/runner/work/my-repo-name/my-repo-name.
GITHUB_SHA The commit SHA that triggered the workflow. For example, ffac537e6cbbf934b08745a378932722df287a53.
GITHUB_REF The branch or tag ref that triggered the workflow. For example, refs/heads/feature-branch-1. If neither a branch or tag is available for the event type, the variable will not exist.
GITHUB_HEAD_REF Only set for forked repositories. The branch of the head repository.
GITHUB_BASE_REF Only set for forked repositories. The branch of the base repository.

Naming conventions for environment variables

Note: GitHub reserves the GITHUB_ environment variable prefix for internal use by GitHub. Setting an environment variable or secret with the GITHUB_ prefix will result in an error.

Any new environment variables you set that point to a location on the filesystem should have a _PATH suffix. The HOME and GITHUB_WORKSPACE default variables are exceptions to this convention because the words "home" and "workspace" already imply a location.

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