Internal Server Error with very simple python script

Question

I'm new to python, and i'm trying to run a simple script (On a Mac if that's important).

Now, this code, gives me Internal Server Error:

#!/usr/bin/python

print 'hi'

But this one works like a charm (Only extra 'print' command):

#!/usr/bin/python
print

print 'hi'

Any explanation? Thanks!

Update:

When I run this script from the Terminal everything is fine. But when I run it from the browser:

http://localhost/cgi-bin/test.py

I get this error (And again, only if i'm not adding the extra print command). I use Apache server of course.

Answer 1

Looks like you're running your script as a CGI-script (your edit confirms that you're using CGI)

...and the initial (empty) print is required to signify the end of the headers.

Check your Apache's error log ( /var/log/apache2/error.log probably) to see if it says ' Premature end of script headers ' ( more info here ).

EDIT : a bit more explanation:

A CGI script in Apache is responsible for generating it's own HTTP response.

An HTTP response consists of a header block, an empty line , and the so-called body contents. Even though you should generate some headers, it's not mandatory to do so. However, you do need to output the empty line; Apache expects it to be there, and if it's not (or if you only output a body which can't be parsed as headers), Apache will generate an error.

That's why your first version didn't work, but your second did: adding the empty print added the required empty line that Apache was expecting.

This will also work:

#!/usr/bin/env python

print "Content-Type: text/html"  # header block
print "Vary: *"                  # also part of the header block
print "X-Test: hello world"      # this too is a header, but a made-up one
print                            # empty line
print "hi"                       # body