Why can't I just add Content-Type:text/html to a text file when Python can?
Question
This will seem like a stupid question to most of you but why can't I do this:
Content-Type:text/html
<html>
<head><title>Hello</title></head>
<body>
<h1>Hello, World!</h1>
</body>
</html>
in a file called test.txt and open it in my browser as html when a Python script can do this:
#!/usr/bin/python
print "Content-type:text/html\r\n\r\n"
print '<html>'
print '<head>'
print '<title>Hello Word - First CGI Program</title>'
print '</head>'
print '<body>'
print '<h2>Hello Word! This is my first CGI program</h2>'
print '</body>'
print '</html>'
and everything works fine. I can't see any difference, they are both printing Content-Type:text/html at the top of the information the browser has requested.
2 answers
solution1
4 ACCPTED 2011-10-21 08:25:06
An HTTP response consists of headers and body, separate by the first \\r\\n\\r\\n received. By the time a web server sends an ordinary file, it has already sent all the headers, and the separator.
When a script is run, however, the headers are not sent automatically.
So in the first case, your webserver guessed the content-type from the extension, and sent appropriate headers, before sending the contents of the file. In the second the script sent an overriding header for the content-type. It's then up to the web-server how it handles this, in terms of inserting the other standard http headers.
EDIT: Apache use mod_mine and /etc/mime.types to map file extensions to Content-Types. It probably defaults to text/plain for anything that doesn't have an extension it understands.
The browser probably works off the extension only if it doesn't have a Content-Type to use.
Plain files are assumed to just contain the data, and the headers are generated by the web server, whereas cgi scripts are expected/allowed to generate their own headers.
solution2
3 2011-10-21 07:34:24
When browsers read directly from a file, they aren't looking for http headers. When a python script is answering a browser's http request, that is different, and the browser expects the first lines to be http headers which it then interprets as you would expect.
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