Print not showing in ipython notebook

I am using ipython notebook (http://ipython.org/notebook.html) to do a demo and it seems like the print function is not working:

The commands in the above picture are rewritten here for clarity.

In [1]: 'hello world'
Out [1]: 'hello world'

In [2]: print 'hello world'

In short, there’s no print output from the [2].

Does anyone know whether it’s a known bug? And does anyone know how to fix it?

Answer

I had a similar printing problem when my first code cell was:

import sys
reload(sys)
sys.setdefaultencoding("utf-8")

Then I’ve commented the second and third lines like this:

import sys
#reload(sys)
#sys.setdefaultencoding("utf-8")

Reset the kernel and re-ran the program and now my print statements are working properly.

Later on, I’ve found that when I was first having the printing problem, all print outputs were actually being sent to the ipython console terminal (on my Linux box), instead of being embed on the notebook.