cal.py

# -*- coding: utf-8 -*-
import os
import cgi
## import cgitb
## cgitb.enable()

caldir_path = "../path/to/cal/"
calset = set(['cal1','cal2','cal3',])

fs = cgi.FieldStorage()
cal = fs.getvalue('cal')
cal_path = os.path.join(caldir_path, cal + '.ics')
ctype = fs.getvalue('ctype')

if ctype == "plain":
    print "Content-Type: text/plain\n"
elif ctype == "html":
    print "Content-Type: text/html\n"
else:
    print "Content-Type: text/calendar; charset=utf-8\n"

if cal in calset:
    print file(cal_path).read()