How to Install pexpect in Python?

pip install pexpect

The Python pexpect library is among the top 100 Python libraries, with more than 24,609,377 downloads. This article will show you everything you need to get this installed in your Python environment.

How to Install pexpect on Windows?

  1. Type "cmd" in the search bar and hit Enter to open the command line.
  2. Type “pip install pexpect” (without quotes) in the command line and hit Enter again. This installs pexpect for your default Python installation.
  3. The previous command may not work if you have both Python versions 2 and 3 on your computer. In this case, try "pip3 install pexpect" or “python -m pip install pexpect“.
  4. Wait for the installation to terminate successfully. It is now installed on your Windows machine.

Here’s how to open the command line on a (German) Windows machine:

Open CMD in Windows

First, try the following command to install pexpect on your system:

pip install pexpect

Second, if this leads to an error message, try this command to install pexpect on your system:

pip3 install pexpect

Third, if both do not work, use the following long-form command:

python -m pip install pexpect

The difference between pip and pip3 is that pip3 is an updated version of pip for Python version 3. Depending on what’s first in the PATH variable, pip will refer to your Python 2 or Python 3 installation—and you cannot know which without checking the environment variables. To resolve this uncertainty, you can use pip3, which will always refer to your default Python 3 installation.

How to Install pexpect on Linux?

You can install pexpect on Linux in four steps:

  1. Open your Linux terminal or shell
  2. Type “pip install pexpect” (without quotes), hit Enter.
  3. If it doesn’t work, try "pip3 install pexpect" or “python -m pip install pexpect“.
  4. Wait for the installation to terminate successfully.

The package is now installed on your Linux operating system.

How to Install pexpect on macOS?

Similarly, you can install pexpect on macOS in four steps:

  1. Open your macOS terminal.
  2. Type “pip install pexpect” without quotes and hit Enter.
  3. If it doesn’t work, try "pip3 install pexpect" or “python -m pip install pexpect“.
  4. Wait for the installation to terminate successfully.

The package is now installed on your macOS.

How to Install pexpect in PyCharm?

Given a PyCharm project. How to install the pexpect library in your project within a virtual environment or globally? Here’s a solution that always works:

  • Open File > Settings > Project from the PyCharm menu.
  • Select your current project.
  • Click the Python Interpreter tab within your project tab.
  • Click the small + symbol to add a new library to the project.
  • Now type in the library to be installed, in your example "pexpect" without quotes, and click Install Package.
  • Wait for the installation to terminate and close all pop-ups.

Here’s the general package installation process as a short animated videoβ€”it works analogously for pexpect if you type in “pexpect” in the search field instead:

Make sure to select only “pexpect” because there may be other packages that are not required but also contain the same term (false positives):

How to Install pexpect in a Jupyter Notebook?

To install any package in a Jupyter notebook, you can prefix the !pip install my_package statement with the exclamation mark "!". This works for the pexpect library too:

!pip install my_package

This automatically installs the pexpect library when the cell is first executed.

How to Resolve ModuleNotFoundError: No module named ‘pexpect’?

Say you try to import the pexpect package into your Python script without installing it first:

import pexpect
# ... ModuleNotFoundError: No module named 'pexpect'

Because you haven’t installed the package, Python raises a ModuleNotFoundError: No module named 'pexpect'.

To fix the error, install the pexpect library using “pip install pexpect” or “pip3 install pexpect” in your operating system’s shell or terminal first.

See above for the different ways to install pexpect in your environment.

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