The first thing you will need to do is to connect the CLI to Salesforce. The CLI provides commands to connect using web-based OAuth flow, JWT token-based flow, and an sfdx auth URL.
Use JWT-based flow for CI. If you are using Salesforce DX with Travis, Circle, or Jenkins, then it's always recommended to use JWT-based flow.
To connect the Dev Hub to the CLI, run the following command:
sfdx force:auth:web:login -r https://login.Salesforce.com
For Sandbox Orgs, use test.Salesforce.com instead.
The following screenshot shows the Terminal once the CLI has been authorized to connect to Salesforce:
