Linux Users: Extra Space in iPython Tab Completion when Using Conda (Fix) @cpcloud

Extra Space Conda iPython Fix.md

Disclaimer: Although I'm a python developer, I'm not someone who has built libraries from source. Use this gist at your own peril.

##Intro

If you're running Linux, you may have installed anaconda to replace your package management needs, and loved it. Except when you fire up iPython you get an annoying "extra space" for your tab completion... that hasn't been patched yet.

When looking here and here, it appears to still be an issue.

With some hand-holding of @cpcloud (as in, "he held mine"), he was able to fix that problem for me today with very little effort.

###Step 1

Make sure you have libreadline-dev installed on you Linux box a la:

$ sudo apt-get install libreadline-dev 

###Step 2

Download and build Python 2.7.8 from source. Can also be found @cpcloud's gist:

$ wget https://www.python.org/ftp/python/2.7.8/Python-2.7.8.tar.xz
$ tar xvf Python-2.7.8.tar.xz

###Step 3

Compile & Make the Install

This portion comes for @kbg 's post about this very issue

$ cd Python-2.7.8
$ ./configure --enable-shared --enable-ipv6 --enable-unicode=ucs4 --prefix=/usr
$ make -j `nproc`

###Step 4

Copy the compiled libreadline.so object into your ../anaconda/lib/python2.7/lib-dynload/ folder.

 #Find where `readline.so` is located
$ find -name 'readline.so'

 #came back ./build/lib.linux-x86_64-2.7/readline.so
$ cp ./build/lib.linux-x86_64-2.7/readline.so ~/anaconda/lib/python2.7/lib-dynload/

###Step 5

Remove the conda readline install

$ conda remove readline

###Step 6

Check to make sure it worked

Close and re-open iPython, and try your tab completion (worked for me).

FYI, the reason this works is that you are linking the Python readline module, readline.so against the system GNU readline library, libreadline.so.6. Although this fixes the extra space issue it makes the Anaconda Python install non-portable which may or may not be a concern.

Thanks for the comment @jjhelmus. Just started using conda, so frankly losing the from iPython was my primary concern. As I don't do much (read: any) environment creation with conda, could you clarify? Are you saying that I won't be able to conda create -n <new_env> now that I've applied this libreadline hack to conda?