Cannot run magic functions in ipython terminal - ipython

Question

I am using Enthought's Canopy environment on a 64 bit Linux OS. Everything works fine in the Ipython console which is attached with the editor. But when I ipython in the terminal and try to use magic functions, I get the following error.
---------------------------------------------------------------------------
error Traceback (most recent call last)
<ipython-input-3-29a4050aa687> in <module>()
----> 1 get_ipython().show_usage()
/home/shahensha/Development/Canopy/appdata/canopy-1.0.3.1262.rh5-x86_64/lib/python2.7/site-packages/IPython/core/interactiveshell.pyc in show_usage(self)
2931 def show_usage(self):
2932 """Show a usage message"""
-> 2933 page.page(IPython.core.usage.interactive_usage)
2934
2935 def extract_input_lines(self, range_str, raw=False):
/home/shahensha/Development/Canopy/appdata/canopy-1.0.3.1262.rh5-x86_64/lib/python2.7/site-packages/IPython/core/page.pyc in page(strng, start, screen_lines, pager_cmd)
188 if screen_lines <= 0:
189 try:
--> 190 screen_lines += _detect_screen_size(screen_lines_def)
191 except (TypeError, UnsupportedOperation):
192 print(str_toprint, file=io.stdout)
/home/shahensha/Development/Canopy/appdata/canopy-1.0.3.1262.rh5-x86_64/lib/python2.7/site-packages/IPython/core/page.pyc in _detect_screen_size(screen_lines_def)
112 # Proceed with curses initialization
113 try:
--> 114 scr = curses.initscr()
115 except AttributeError:
116 # Curses on Solaris may not be complete, so we can't use it there
/home/shahensha/Development/Canopy/appdata/canopy-1.0.3.1262.rh5-x86_64/lib/python2.7/curses/__init__.pyc in initscr()
31 # instead of calling exit() in error cases.
32 setupterm(term=_os.environ.get("TERM", "unknown"),
---> 33 fd=_sys.__stdout__.fileno())
34 stdscr = _curses.initscr()
35 for key, value in _curses.__dict__.items():
error: setupterm: could not find terminfo database
So, I installed a bare bones iPython shell which is not the one provided by Canopy and tried the same magic functions in there and it works fine.
Have I done something wrong with the installation? Please help
Thanks a lot
shahensha

Answer 1

This is not a solution, but just an observation. My desktop is MacOS-X and I connect to a Centos machine to run Enthought Canopy both 64 bit. I get the same error message as OP if I ssh from iterm2, but not if I use the Terminal app.
I am not sure what the underlying reason is, but may be someone can verify if a similar situation is true for linux. Interestingly I can use either iterm2 or Terminal on the local canopy without any issues.
Update:
I just noticed that the TERM environment variable in iterm2 was set to "xterm" while the Terminal app was showing "xterm-256color". Issuing the command export TERM="xterm-256color" before running the Canopy ipython in terminal solves the issue for me in iterm2.

Answer 2

Problem reproduction:
$ python -c 'import curses; curses.setupterm()'
Traceback (most recent call last):
File "<string>", line 1, in <module>
_curses.error: setupterm: could not find terminfo database
This irc log gave me the idea that this error was to do with libncursesw.
My Canopy version is 1.0.3.1262.rh5-x86_64. I have installed it to ~/src/canopy.
In ~/src/canopy/appdata/canopy-1.0.3.1262.rh5-x86_64/lib we can see that my canopy install has libncursesw.so.5.7.
My machine (Debian Wheezy 64bit) has libncursesw.so.5.9 (in /lib/x86_64-linux-gnu/libncursesw.so.5.9). I made canopy use this. You can toggle the problem on / off by using LD_PRELOAD and pointing at the .so file.
Solution
Replace libncurses.so.5.7 with libncurses.so.5.9:
CANOPYDIR=$HOME/src/canopy
CANOPYLIBS=$CANOPYDIR/appdata/canopy-1.0.3.1262.rh5-x86_64/lib/
SYSTEMLIBS=/lib/x86_64-linux-gnu
cp $SYSTEMLIBS/libncurses.so.5.9 $CANOPYLIBS
ln -sf $CANOPYLIBS/libncurses.so.5.9 $CANOPYLIBS/libncurses.so.5

Answer 3

It appears that Canopy User Python is not your default. See this article:
https://support.enthought.com/entries/23646538-Make-Canopy-s-Python-be-your-default-Python-i-e-on-the-PATH-
Update: Not true here -- instead, see batu's workaround answer.