To deploy from the command line you must first install the Vercel CLI globally.
npm i -g vercel
Run the vercel command to deploy your project.
vercel
Declare an environment variable.
APP_URL=YOUR_APP_URL_HERE
(e.g. APP_URL=https://example.org)
After the first deployment this command will deploy to a preview branch. You will need to include --prod to push changes directly to the live site for future deployments.
vercel --prod