How do I find the current machine's full hostname in C (hostname and domain information)?

Question

In a C project (POSIX), how do I get the fully qualified name for the current system?

For example, I can get just the hostname of my machine by doing gethostna

Answer 1

The easy way, try uname()

If that does not work, use gethostname() then gethostbyname() and finally gethostbyaddr()

The h_name of hostent{} should be your FQDN