Command:
curl https://git.io/ -i -F "url=https://github.com/YOUR_GITHUB_URL" -F "code=YOUR_CUSTOM_NAME"
URLs that can be created is from:
https://github.com/*
https://*.github.com
https://*.github.com/*
https://*.github.io
https://*.github.io/*
If you accidentally make a typo in the custom name, you can add ?
at the end in your GitHub URL.
curl https://git.io/ -i -F "url=https://github.com/YOUR_GITHUB_URL?" -F "code=YOUR_CUSTOM_NAME"
If you want to revoke your custom name, you should contact GitHub Support Team.