CGI or Common Gateway Interface allow servers, primarily HTTP servers, to interface with external programs like Python, Perl, Ruby scripts or even binary programs written in C/C++. The most popular & most used web server - Apache - can easily be configured for CGI scripts. Let's look at configuring a few popular web servers to run CGI scripts. Configuring Web Server Apache I am using a directory py-bin you may change this to whatever you like, cgi-bin is very popular. Remember to have the executable bit set for your CGI scripts. Code: ScriptAlias /py-bin/ <Directory "/var/www/py-bin"> AllowOverride None Options ExecCGI Order allow,deny Allow from all </Directory> nGinx Wiki Basics The basic HTTP response can be divided into two parts, the header and the body, so here in the CGI scripts we need to do the same, follow the example code below: Code: #!/usr/bin/python ## Headers print "Content-Type: text/html" ## telling what type of document we are sending print ## a blank line to separate the headers from the body ## body print "<h1>Hello World!</h1>" In Python we would be using the cgi module to ease our tasks like form data, cookies, etc. All CGI scripts have access to the environment variables provided by the web server, below we'll be looking a script which will print all environment variables. Code: #!/usr/bin/python import os print "Content-type: text/html" print print "<h3>Environment Variables</h3>" for param in os.environ.keys(): print "<b>%s</b>: %s</br>" % (param,os.environ[param]) Forms Form data passed by GET/POST methods can be accessed using the Python cgi module, the demo script that follows should be enough to get an idea of it's usage: Code: #!/usr/bin/python # import cgi module import cgi # get form data using the FieldStorage method, which returns an object form = cgi.FieldStorage() # Get data from fields user_name = form.getvalue('name') user_city = form.getvalue('city') print "Content-Type: text/html" print print "Welcome %s, from %s" % (user_name,user_city) Cookies Reading & setting cookies in Python CGI scripts is made easier with the Python Cookie module, let's see how to work with cookies. Code: #!/usr/bin/python ## load the modules import Cookie, datetime ## calculate the expiration time, you can set any expiry as you like expiration = datetime.datetime.now() + datetime.timedelta(days=30) ## Cookie object cookie = Cookie.SimpleCookie() ## cookie 1 cookie["user_pref"] = 'name=Pradeep&loc=Kol' cookie["user_pref"]["domain"] = ".pradeep.net.in" cookie["user_pref"]["path"] = "/" cookie["user_pref"]["expires"] = expiration.strftime("%a, %d-%b-%Y %H:%M:%S PST") ## cookie 2 cookie["theme"] = 'thm=abc.html&color=red' cookie["theme"]["domain"] = ".pradeep.net.in" cookie["theme"]["path"] = "/" cookie["theme"]["expires"] = expiration.strftime("%a, %d-%b-%Y %H:%M:%S PST") ## output the cookie with the headers print "Content-type: text/html" print cookie.output() print ## body print "Cookie set with: <br/><pre>" + cookie.output() + "</pre>"