Store information in variables

About variables

Variables provide a way to store and reuse non-sensitive configuration information. You can store any configuration data such as compiler flags, usernames, or server names as variables. Variables are interpolated on the runner machine that runs your workflow. Commands that run in actions or workflow steps can create, read, and modify variables.

You can set your own custom variables or use the default environment variables that GitHub sets automatically. For more information, see Default environment variables.

You can set a custom variable in two ways.

• To define an environment variable for use in a single workflow, you can use the env key in the workflow file. For more information, see Defining environment variables for a single workflow.
• To define a configuration variable across multiple workflows, you can define it at the organization, repository, or environment level. For more information, see Defining configuration variables for multiple workflows.

Defining environment variables for a single workflow

To set a custom environment variable for a single workflow, you can define it using the env key in the workflow file. The scope of a custom variable set by this method is limited to the element in which it is defined. You can define variables that are scoped for:

• The entire workflow, by using env at the top level of the workflow file.
• The contents of a job within a workflow, by using jobs.<job_id>.env.
• A specific step within a job, by using jobs.<job_id>.steps[*].env.

name: Greeting on variable day

on:
  workflow_dispatch

env:
  DAY_OF_WEEK: Monday

jobs:
  greeting_job:
    runs-on: ubuntu-latest
    env:
      Greeting: Hello
    steps:
      - name: "Say Hello Mona it's Monday"
        run: echo "$Greeting $First_Name. Today is $DAY_OF_WEEK!"
        env:
          First_Name: Mona

name: Greeting on variable day

on:
  workflow_dispatch

env:
  DAY_OF_WEEK: Monday

jobs:
  greeting_job:
    runs-on: ubuntu-latest
    env:
      Greeting: Hello
    steps:
      - name: "Say Hello Mona it's Monday"
        run: echo "$Greeting $First_Name. Today is $DAY_OF_WEEK!"
        env:
          First_Name: Mona

You can access env variable values using runner environment variables or using contexts. The example above shows three custom variables being used as runner environment variables in an echo command: $DAY_OF_WEEK, $Greeting, and $First_Name. The values for these variables are set, and scoped, at the workflow, job, and step level respectively. The interpolation of these variables happens on the runner.

The commands in the run steps of a workflow, or a referenced action, are processed by the shell you are using on the runner. The instructions in the other parts of a workflow are processed by GitHub Actions and are not sent to the runner. You can use either runner environment variables or contexts in run steps, but in the parts of a workflow that are not sent to the runner you must use contexts to access variable values. For more information, see Using contexts to access variable values.

Because runner environment variable interpolation is done after a workflow job is sent to a runner machine, you must use the appropriate syntax for the shell that's used on the runner. In this example, the workflow specifies ubuntu-latest. By default, Linux runners use the bash shell, so you must use the syntax $NAME. By default, Windows runners use PowerShell, so you would use the syntax $env:NAME. For more information about shells, see Workflow syntax for GitHub Actions.

Naming conventions for environment variables

When you set an environment variable, you cannot use any of the default environment variable names. For a complete list of default environment variables, see Default environment variables below. If you attempt to override the value of one of these default variables, the assignment is ignored.

Defining configuration variables for multiple workflows

You can create configuration variables for use across multiple workflows, and can define them at either the organization, repository, or environment level.

For example, you can use configuration variables to set default values for parameters passed to build tools at an organization level, but then allow repository owners to override these parameters on a case-by-case basis.

When you define configuration variables, they are automatically available in the vars context. For more information, see