Get the fully qualified domain name of the host where the function is executed.

get_fully_qualified_domain_name.py

#!/usr/bin/env python

"""
The above is the most portable shebang,

#!/usr/bin/env python

is more portable because in general the program /usr/bin/env can be
used to "activate" the desired command without full path.

Otherwise, you would have to specify the full path of the Python
interpreter, which can vary.

So no matter if the Python interpreter was in /usr/bin/python or in
/usr/local/bin/python or in your home directory, using 
#!/usr/bin/env python will work.
"""

import socket

def get_fully_qualified_domain_name():
  """Get the fully qualified domain name of the host where the function is executed.
  
  A device with the hostname myhost and the parent domain name
  example.com has the fully qualified domain name (FQDN)
  myhost.example.com. The FQDN uniquely distinguishes the device from
  any other hosts called myhost in other domains.
  
  See: https://en.wikipedia.org/wiki/Fully_qualified_domain_name

  """
  return socket.gethostbyaddr(socket.gethostname())[0]


print get_fully_qualified_domain_name()