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Basic Usage


PySpelling is a module to help with automating spell checking in a project with Aspell or Hunspell. It is essentially a wrapper around the command line utility of these two spell checking tools, and allows you to setup different spelling tasks for different file types. You can apply specific and different filters and options to each task. PySpelling can also be used in CI environments to fail the build if there are misspelled words.

Aspell and Hunspell are very good spell checking tools. Aspell particularly comes with a couple of filters, but the filters are limited in types and aren't extremely flexible. PySpelling was created to work around Aspell's and Hunspell's filtering shortcomings by creating a wrapper around them that could be extended to handle more kinds of file formats and provide more advanced filtering. If you need to filter out specific HTML tags with specific IDs or class names, PySpelling can do it. If you want to scan Python files for docstrings, but also avoid specific content within the docstring, you can do that as well. If PySpelling doesn't have a filter you need, with access to so many available Python modules, you can easily write your own.

Computer:pyspelling facelessuser$ pyspelling
Misspelled words:
<html-content> site/index.html: P

Misspelled words:
<context> pyspelling/ Pep440Version

!!!Spelling check failed!!!


PySpelling is a wrapper around either Aspell or Hunspell. If you do not have a working Aspell or Hunspell on your system, PySpelling will not work. It is up to the user to either build locally or acquire via a package manager a working spell checker installation. PySpelling pre-processes files with Python filters, and then sends the resulting text to the preferred spell checker via command line.


Installation is easy with pip:

$ pip install pyspelling

If you want to manually install it, run python build and python install.

Command Line Usage

usage: spellcheck [-h] [--version] [--verbose] [--name NAME] [--binary BINARY]
                  [--config CONFIG] [--spellchecker SPELLCHECKER]

Spell checking tool.

optional arguments:
  -h, --help            show this help message and exit
  --version             show program's version number and exit
  --verbose, -v         Verbosity level.
  --name NAME, -n NAME  Specific spelling task by name to run.
  --binary BINARY, -b BINARY
                        Provide path to spell checker's binary.
  --config CONFIG, -c CONFIG
                        Spelling config.
                        Choose between aspell and hunspell

PySpelling can be run with the command below (assuming your Python bin/script folder is in your path). By default it will look for the spelling configuration file .pyspelling.yml.

$ pyspelling

If you have multiple Python versions, you can run the PySpelling associated with that Python version by appending the Python major and minor version:

$ pyspelling3.7

To specify a specific configuration other than the default, or even point to a different location:

$ pyspelling -c myconfig.yml

To run a specific spelling task in your configuration file by name, you can use the name option. You can even specify multiple names if desired. You cannot use name and group together:

$ pyspelling -n my_task -n my_task2

If you've specified groups for your tasks, you can run all tasks in a group with the group option. You can specify multiple groups if desired. You cannot use name and group together.

$ pyspelling -g my_group -g my_group2

If you've specified exactly one name via the name option, you can override that named task's source patterns with the source option. You can specify multiple source patterns if desired.

$ pyspelling -n my_task -S "this/specific/file.txt" -S "these/specific/files_{a,b}.txt"

To run a more verbose output, use the -v flag. You can increase verbosity level by including more vs: -vv. You can currently go up to four levels.

$ pyspelling -v

If the binary for your spell checker is not found in your path, you can provide a path to the binary.

$ pyspelling -b "path/to/aspell"

You can specify the spell checker type by specifying it on the command line. PySpelling supports hunspell and aspell, but defaults to aspell. This will override the preferred spellchecker setting in the configuration file.

$ pyspelling -s hunspell

Supported Spell Check Versions

PySpelling is tested with Hunspell 1.6+, and recommends using only 1.6 and above. Some lower versions might work, but none have been tested, and related issues will probably not be addressed.

I usually patch the English Hunspell dictionary that I use to add apostrophes, if not present. Apostrophe support is a must for me. I also prefer to not include numbers as word characters (like Aspell) does as I find them problematic, but this is just my personal preference. Below is a patch I use on an OpenOffice dictionary set (git://

diff --git a/en/en_US.aff b/en/en_US.aff
index d0cccb3..4258f85 100644
--- a/en/en_US.aff
+++ b/en/en_US.aff
@@ -14,7 +14,7 @@ ONLYINCOMPOUND c
-WORDCHARS 0123456789

 PFX A Y 1
 PFX A   0     re   

PySpelling is also tested on Aspell 0.60+ (which is recommended), but should also work on the 0.50 series. 0.60+ is recommended as spell checking is better in the 0.60 series.

PySpelling disables all native Aspell filters by default. If you need to enable Aspell's native filters, you can do so via Aspell's builtin options. For more information, see Aspell configuration options.

New in 2.4.0

Starting in 2.4.0, PySpelling ensures filters that are native to the spell checker are disabled by default.

Usage in Linux

Aspell and Hunspell is most likely available in your distro's package manager. You need to install both the spell checker and the dictionaries, or provide your own custom dictionaries. The option to build manually is always available as well. See your preferred spell checker's manual for more information on building manually.

Ubuntu Aspell install example:

$ sudo apt-get install aspell aspell-en

Ubuntu Hunspell install example:

$ sudo apt-get install hunspell hunspell-en-us

Usage in macOS

Aspell and Hunspell can be included via package managers such as Homebrew. You need to install both the spell checker and the dictionaries, or provide your own custom dictionaries. The option to build manually is always available as well. See your preferred spell checker's manual for more information on building manually.

Homebrew Aspell install examples:

$ brew install aspell

Homebrew Hunspell install examples:

$ brew install hunspell

Don't forget to download dictionaries and put them to /Library/Spelling/.

Usage in Windows

Installing Aspell and/or Hunspell in Windows is traditionally done through either a Cygwin or MSYS2/MinGW environment. If using MYSYS2/MinGW, you can usually install both packages via Pacman. You need to install both the spell checker and the dictionaries, or provide your own custom dictionaries. The option to build manually is always available as well. See your preferred spell checker's manual for more information on building manually.

Pacman Aspell install example:

$ pacman -S mingw-w64-x86_64-aspell mingw-w64-x86_64-aspell-en

For Aspell, it has been noted that the way the default configuration is configured, builtin Aspell filters are often inaccessible as the configuration seems to configure paths with mixed, incompatible slash style (backslash and forward slash). By creating your own override configuration, and using forward slashes only can fix the issue. You must manually specify a proper data-dir and dict-dir override path. This is done in our appveyor.yml file for our own personal tests, so you can check it out to see what is done. After fixing the configuration file, you should have everything working.

Pacman Hunspell install example:

$ pacman -S mingw-w64-x86_64-hunspell mingw-w64-x86_64-hunspell-en

If you are dealing with Unicode text, Windows often has difficulty showing it in the console. Using Windows Unicode Console to patch your Windows install can help. On Python 3.6+ it might not be needed at all. Certain specialty consoles on Windows may report confusing information related to what encoding is used in the console. It is left to the user to resolve console Unicode issues, though proposals for better ways to handle this would be considered.

Alternatively, you can just setup PySpelling in a Windows Subsystem for Linux environment and just use the Linux instructions.

Usage in CI

PySpelling was originally written so that it could be used to automate tests in a CI environment. Any automated CI can use PySpelling assuming the environment is setup appropriately. On most systems it can be pretty straight forward, on systems like Windows, it may be a bit more complicated as you will have to also setup a Cygwin, MSYS2/MinGW, Windows Subsystem for Linux environment.

We won't go into all possible CI environments in this documentation, but we will cover how to get PySpelling up and running on GitHub's CI environment. In the past, PySpelling has successfully been used in Travis CI, AppVeyor, and many others.

In order to get running in GitHub's CI, you can follow the steps below:

  1. Create a spelling task under jobs.
  2. Specify a Linux environment as it is one of the easiest to configure and get running.
  3. Use the actions/checkout action to checkout your project.
  4. Setup your Python environment using the actions/setup-python action.
  5. Install dependencies you may need. Below, we update pip and setuptools and install pyspelling. You may require additional dependencies depending on spelling extensions used, or if pre-building of documents is needed.
  6. Install Aspell and Aspell dictionaries. You are also free to use Hunspell if preferred.
  7. Below we've allowed for a Build documents step where you can build documentation or do any other file preprocessing that is required for your specific environment.
  8. Lastly, run PySpelling.
    runs-on: ubuntu-latest
    - uses: actions/checkout@v1
    - name: Set up Python 3.7
      uses: actions/setup-python@v1
        python-version: 3.7
    - name: Install dependencies
      run: |
        python -m pip install --upgrade pip setuptools
        python -m pip install pyspelling
        # Install any additional libraries required: additional plugins, documentation building libraries, etc.
    - name: Install Aspell
      run: |
        sudo apt-get install aspell aspell-en
    - name: Build documents
      run: |
        # Perform any documentation building that might be required
    - name: Spell check
       run: |
         python -m pyspelling

In this project, we actually use tox to make running our tests locally and in CI easier. If you would like to use tox as well, you can check out how this project does it by taking a look at the source.

Last update: April 15, 2020