Question

Is there a way to tell the interactive Python shell to preserve its history of executed commands between sessions?

While a session is running, after commands have been executed, I can arrow up and access said commands, I’m just wondering if there is some way for a certain number of these commands to be saved until the next time I use the Python shell.

This would be very useful since I find myself reusing commands in a session, that I used at the end of the last session.

Answer 1

Sure you can, with a small startup script. From Interactive Input Editing and History Substitution in the python tutorial:

# 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=~/.pystartup" in bash.

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

From Python 3.4 onwards, the interactive interpreter supports autocompletion and history out of the box:

Tab-completion is now enabled by default in the interactive interpreter on systems that support readline. History is also enabled by default, and is written to (and read from) the file ~/.python-history.