+1  A: 
J.F. Sebastian
:/ That's really annoying, I've tried disabling any profile customisation, using the latest stable version (ipython 0.9.1), two different machines, using different terminal profiles.. What terminal emulator/shell/python/ipython version etc are you using?
dbr
Never mind the above comment!
dbr
+3  A: 

Aha! I had an old version of the Python readline module - installing the latest from http://ipython.scipy.org/dist/ and it works perfectly!

sudo easy_install http://ipython.scipy.org/dist/readline-2.5.1-py2.5-macosx-10.5-i386.egg
dbr
+1  A: 

Got this problem on Snow Leopard. Installing a new version of readline from http://pypi.python.org/pypi/readline/ fixes it:

sudo easy_install http://pypi.python.org/packages/2.6/r/readline/readline-2.6.4-py2.6-macosx-10.6-universal.egg
aam
My stock Snow Leopard has python2.6.1 and the 2.6.4 version did not work. Also, here's the link to use an alternate mirror since the main pypi is slow lately.sudo easy_install http://d.pypi.python.org/packages/2.6/r/readline/readline-2.6.1-py2.6-macosx-10.6-universal.egg
Adam Nelson
Good points. I should add that I am using the MacPorts version of python -- running 'python_select -s' returns 'python26' instead of 'python26-apple', which shows up in 'python_select -l'.
aam