To find out who owns a domain name on a Linux or Unix system, you can use the whois command to query a domain name registry database. The whois command is a utility that allows you to look up information about a domain name, such as the owner, the registrar, and the expiration date.
To use the whois command, you simply need to specify the domain name as an argument. For example, to find out who owns the domain example.com, you can use the following command:
whois example.com
This will return information about the domain example.com, including the owner's contact information, the registrar, and the expiration date.
You can also use the -h option to specify the whois server to query, if the default server does not contain the information you are looking for. For example:
whois -h whois.example.com example.com
This will query the whois server at whois.example.com for information about the domain example.com.
Keep in mind that the whois command may not work for all domain names, and the information returned by the command may not be complete or up-to-date. If you are unable to find the information you are looking for using the whois command, you may need to consult other resources or seek assistance from a qualified domain name administrator.
For more information about how to use the whois command to find out who owns a domain name on a Linux or Unix system, you can consult the whois documentation or use the man whois command to see the manual page.