How to save a Python interactive session?

From Andrew Jones's website (archived):

import readline
readline.write_history_file('/home/ahj/history')

IPython is extremely useful if you like using interactive sessions. For example for your use-case there is the %save magic command, you just input %save my_useful_session 10-20 23 to save input lines 10 to 20 and 23 to my_useful_session.py (to help with this, every line is prefixed by its number).

Furthermore, the documentation states:

This function uses the same syntax as %history for input ranges, then saves the lines to the filename you specify.

This allows for example, to reference older sessions, such as

%save current_session ~0/
%save previous_session ~1/

Look at the videos on the presentation page to get a quick overview of the features.

There is a way to do it. Store the file in ~/.pystartup...

# Add auto-completion and a stored history file of commands to your Python
# interactive interpreter. Requires Python 2.0+, readline. Autocomplete is
# bound to the Esc key by default (you can change it - see readline docs).
#
# Store the file in ~/.pystartup, and set an environment variable to point
# to it:  "export PYTHONSTARTUP=/home/user/.pystartup" in bash.
#
# Note that PYTHONSTARTUP does *not* expand "~", so you have to put in the
# full path to your home directory.

import atexit
import os
import readline
import rlcompleter

historyPath = os.path.expanduser("~/.pyhistory")

def save_history(historyPath=historyPath):
    import readline
    readline.write_history_file(historyPath)

if os.path.exists(historyPath):
    readline.read_history_file(historyPath)

atexit.register(save_history)
del os, atexit, readline, rlcompleter, save_history, historyPath

and then set the environment variable PYTHONSTARTUP in your shell (e.g. in ~/.bashrc):

export PYTHONSTARTUP=$HOME/.pystartup

You can also add this to get autocomplete for free:

readline.parse_and_bind('tab: complete')

Please note that this will only work on *nix systems. As readline is only available in Unix platform.

If you are using IPython you can save to a file all your previous commands using the magic function %history with the -f parameter, p.e:

%history -f /tmp/history.py