How to ignore all domains except those specified in robots.txt?

Question

robots.txt

In order to avoid getting into the index of developer forks of the project, as well as all the different domain variations like www. prefixes, you need to set a rule in robots.txt to ignore all domains except the specified one. How to do it?
And also how to make ignoring some directories also on this domain?

Answer 1

If you mean under

all-different domain variations

- subdomains. Then you need to write in the root of each subdomain in robots.txt:
User-agent: *
Disallow: /
To disable the index of certain folders, use:
Disallow: /fork/
To specify the main host
Host: www.myhost.ru