Reading a client's header from Python CGI script?

If you are running as a CGI, you can't read the HTTP header directly, but the web server put much of that information into environment variables for you. You can just pick it out of os.environ[]

The list of environment variables that might be there is pretty long. You can find it by doing a web search for "common gateway interface". For example, in http://www.ietf.org/rfc/rfc3875.txt they are called "meta-variables".

These are given to the CGI script through the environment:

import os
user_agent = os.environ["HTTP_USER_AGENT"]
ip = os.environ["REMOTE_ADDR"]

As this page explains, most HTTP request headers are made available to your CGI script via environment variables. Run cgi.test() instead of your script to see the environment (including HTTP request headers) shown back to your visiting browser.