Unix заменить все строки в файле, начинающиеся со строки, на переменную [duplicate]

No puedes.

If all of your subscriptions expire and you have no other active subscriptions in your organization, you retain the right to use the software under the applicable license terms. However, your entire environment will no longer receive any of the subscription benefits, including:

• The latest certified software versions.
• Security errata and bug fixes...

https://www.redhat.com/en/about/subscription-model-faq