Question

Many times I will use the Python interpreter to inspect variables and step through commands before I actually write to a file. However by the end I have around 30 commands in the interpreter, and have to copy/paste them into a file to run. Is there a way I can export/write the Python interpreter history into a file?

For example

>>> a = 5
>>> b = a + 6
>>> import sys
>>> export('history', 'interactions.py') 

And then I can open the interactions.py file and read:

a = 5
b = a + 6
import sys

Answer 1

IPython is extremely useful if you like using interactive sessions. For example for your usecase there is the save 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)

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

::OR::

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

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.