Seeing escape characters when pressing the arrow keys in python shell

On OS X, Xcode updates sometimes break readline. Solution:

brew uninstall readline
brew upgrade python3
brew install readline
pip3 install readline

If the problem still persists, try to remove readline using pip and install it using easy_install:

pip3 uninstall readline
easy_install readline

Looks like readline is not enabled. Check if PYTHONSTARTUP variable is defined, for me it points to /etc/pythonstart and that file is executed by the python process before going interactive, which setups readline/history handling.

Thanks to @chown here is the docs on this: http://docs.python.org/2/tutorial/interactive.html

I have run into this issue recently and after reading a lot about pip install readline (does not work for mac osx) and pip install gnureadline and not being satisfied, this is now my setup which enables using arrow keys in any python console:

1. install gnureadline using pip install gnureadline

now you can either do import gnureadline and arrow keys should work as expected. To make them work automatically follow the following steps:

2. create (or append to) file ~/.startup.py: import gnureadline
3. append to file ~/.bash_profile: export PYTHONSTARTUP=~/.startup.py

One thing that does not work, but did in my previous setup is: automatic import of gnureadline on pdb.set_trace(). If anyone has a good solution to this problem I would be grateful for a comment.

I had problems with shell history(tab/arrows commands) of Python 3.6.x on Ubuntu 16.04 LTS.

Python 3.6.x was installed from source.

What solved for me was install the module "gnureadline" as said by user12345, using this command line:

sudo pip3.6 install gnureadline

:)

Was impacted after upgrading Mac to High Sierra, this successfully resolved it for me:

brew unlink python
xcode-select --install
brew install python

readline module has been deprecated which will cause invalid pointer error in latest python versions when executing quit() or exit() in python shell. pip install gnureadline instead

None of these answers worked for me on two different version of Ubuntu. What worked for me, but isn't a true fix, is wrapping my python code in a call to rlwrap (available in the ubuntu repositories):

rlwrap python mycode.py

For those using conda, installing the readline package from conda-forge channel will fix the problem:

conda install -c conda-forge readline=6.2

Did you call ssh with the -t parameter to tell ssh to allocate a virtual terminal for you?

From the man page:

-t
Force pseudo-tty allocation. This can be used to execute arbitrary screen-based programs on a remote machine, which can be very useful, e.g. when implementing menu services. Multiple -t options force tty allocation, even if ssh has no local tty.

Additionally you may also have to set the TERM environment variable on the server correctly as suggested in another post.

On Mac OS X Mojave 10.14.6 with various historical installs via brew I solved this with:

brew reinstall python2

There is likely no magic bullet given everyone has a different install scenario. I tried the above as well so it may have been a combination of a few of the answers. Brew defaults to python3 so if you installed the python2 package it also needs to be reinstalled.

Have you tried using a different SSH client? Some SSH clients have special, built-in keymappings for different remote processes. I ran into this one a lot with emacs.

What client are you using? I'd recommend trying Putty and SecureCRT to compare their behavior.

How's your env variable $TERM set [a] when things work fine and [b] when they don't? Env settings are often the key to such problems.

On MacOsx, I fixed this by reinstalling readline

brew reinstall readline

In Unbuntu or Mint, if you are using pyenv,

sudo apt install libreadline-dev
pyenv uninstall 3.8.8
pyenv install 3.8.8

Once installing libreadline-dev, you don't need to install pip install gnureadline on every python version.

you can switch from 'sh" to "bash" by

$ /sh/bash