How to Get the Command History in Python?

If you’re working with the command line in Windows or the terminal in Linux and macOS, you know about the feature of the command-line history. You can access all previously issued commands with the arrow up or arrow down keys.

As a Python coder, you want to be able to control everything from your Python shell. This naturally leads to the following question.

Problem Formulation: How to get the entire command history in Python—all commands that have been executed in the interactive Python session?

Method 1: Python 3 One-Liner with readline.get_history_item()

The readline module works in combination with Unix-like operating systems such as macOS and Linux. This one-liner is easy to copy and paste into your Python shell to access the command history in Python:

import readline; print('\n'.join([str(readline.get_history_item(i + 1)) for i in range(readline.get_current_history_length())]))

Method 2: Python 3 Multi-Liner with readline

This multi-liner does the same as the previous one-liner—it’s just more readable and less concise. 😉

import readline
for i in range(readline.get_current_history_length()):
    print(readline.get_history_item(i + 1))

Method 3: Python 2 One-Liner with readline

Okay, some people may still use Python 2. In this case, you’ll need to slightly modify the previous one-liner to obtain:

import readline; print '\n'.join([str(readline.get_history_item(i + 1)) for i in range(readline.get_current_history_length())])

Method 4: Print File for Unix-Like OS

The following file contains the history: ~/.python_history. You can access it with the following command on macOS or Linux:

$ cat ~/.python_history

Note that you need to quit() the interpreter for the current session history to be included in the file ~/.python_history.

Method 5: Write History Into a File

The readline module also provides a function write_history_file() to write the command history into a file with name, say, 'python_command_history.py‘. Pass the desired filename into the function and Python will dump the Python commands into a new file with the given filename.

import readline
readline.write_history_file('python_command_history.py')

Method 6: Use Up and Down Arrows If You’re Running Python Shell From Command Line

If you’ve opened a Python session from the command line, you can use up and down arrows to get the previous commands because Python uses the same history mechanism as the operating system:

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References