doccmd 2025.3.6

Run commands against code blocks in reStructuredText and Markdown files.

doccmd

A command line tool for running commands against code blocks in documentation files. This allows you to run linters, formatters, and other tools against the code blocks in your documentation files.

• Installation

  • With pip

  • With Homebrew (macOS, Linux, WSL)

    • Pre-built Linux (x86) binaries

  • Using doccmd as a pre-commit hook

• Usage example

• What does it work on?

• Formatters and padding

• File names and linter ignores

• Skipping code blocks

• Grouping code blocks

  • Using groups with formatters

• Full documentation

Installation

With pip

Requires Python 3.11+.

$ pip install doccmd

With Homebrew (macOS, Linux, WSL)

Requires Homebrew.

$ brew tap adamtheturtle/doccmd
$ brew install doccmd

Pre-built Linux (x86) binaries

$ curl --fail -L https://github.com/adamtheturtle/doccmd/releases/download/2025.02.20.7/doccmd-linux -o /usr/local/bin/doccmd &&
    chmod +x /usr/local/bin/doccmd

Using doccmd as a pre-commit hook

To run doccmd with pre-commit, add hooks like the following to your .pre-commit-config.yaml:

-   repo: https://github.com/adamtheturtle/doccmd-pre-commit
    rev: v2025.02.20.7
    hooks:
    -   id: doccmd
        args: ["--language", "shell", "--command", "shellcheck --shell=bash"]
        additional_dependencies: ["shellcheck-py"]

Usage example

# Run mypy against the Python code blocks in README.md and CHANGELOG.rst
$ doccmd --language=python --command="mypy" README.md CHANGELOG.rst

# Run gofmt against the Go code blocks in README.md
# This will modify the README.md file in place
$ doccmd --language=go --command="gofmt -w" README.md

# or type less... and search for files in the docs directory
$ doccmd -l python -c mypy README.md docs/

What does it work on?

• reStructuredText (.rst)

.. code-block:: shell

   echo "Hello, world!"

.. code:: shell

   echo "Or this Hello, world!"

• Markdown (.md)

By default, .md files are treated as MyST files. To treat them as Markdown, use --myst-extension=. --markdown-extension=.md.

```shell
echo "Hello, world!"
```

• MyST (.md with MyST syntax)

```{code-block} shell
echo "Hello, world!"
```

```{code} shell
echo "Or this Hello, world!"
```

• Want more? Open an issue!

Formatters and padding

Running linters with doccmd gives you errors and warnings with line numbers that match the documentation file. It does this by adding padding to the code blocks before running the command.

Some tools do not work well with this padding, and you can choose to obscure the line numbers in order to give the tool the original code block’s content without padding, by using the --no-pad-file and --no-pad-groups flag. See using_groups_with_formatters for more information.

File names and linter ignores

doccmd creates temporary files for each code block in the documentation file. These files are created in the same directory as the documentation file, and are named with the documentation file name and the line number of the code block. Files are created with a prefix set to the given --temporary-file-name-prefix argument (default doccmd).

You can use this information to ignore files in your linter configuration.

For example, to ignore a rule in all files created by doccmd in a ruff configuration in pyproject.toml:

[tool.ruff]

lint.per-file-ignores."doccmd_*.py" = [
   # Allow hardcoded secrets in documentation.
   "S105",
]

Skipping code blocks

Code blocks which come just after a comment matching skip doccmd[all]: next are skipped.

To skip multiple code blocks in a row, use skip doccmd[all]: start and skip doccmd[all]: end comments surrounding the code blocks to skip.

Use the --skip-marker option to set a marker for this particular command which will work as well as all. For example, use --skip-marker="type-check" to skip code blocks which come just after a comment matching skip doccmd[type-check]: next.

To skip a code block for each of multiple markers, for example to skip a code block for the type-check and lint markers but not all markers, add multiple skip doccmd comments above the code block.

The skip comment will skip the next code block which would otherwise be run. This means that if you run doccmd with --language=python, the Python code block in the following example will be skipped:

<-- skip doccmd[all]: next -->

```{code-block} shell
echo "This will not run because the shell language was not selected"
```

```{code-block} python
print("This will be skipped!")
```

Therefore it is not recommended to use skip doccmd[all] and to instead use a more specific marker. For example, if we used doccmd with --language=shell and --skip-marker=echo the following examples show how to skip code blocks in different formats:

• reStructuredText (.rst)

.. skip doccmd[echo]: next

.. code-block:: shell

   echo "This will be skipped!"

.. code-block:: shell

   echo "This will run"

• Markdown (.md)

<-- skip doccmd[echo]: next -->

```shell
echo "This will be skipped!"
```

```shell
echo "This will run"
```

• MyST (.md with MyST syntax)

% skip doccmd[echo]: next

```{code-block} shell
echo "This will be skipped!"
```

```{code-block} shell
echo "This will run"
```

Grouping code blocks

You might have two code blocks like this:

"""Example function which is used in a future code block."""


def my_function() -> None:
    """Do nothing."""

my_function()

and wish to type check the two code blocks as if they were one. By default, this will error as in the second code block, my_function is not defined.

To treat code blocks as one, use group doccmd[all]: start and group doccmd[all]: end comments surrounding the code blocks to group. Grouped code blocks will not have their contents updated in the documentation file. Error messages for grouped code blocks may include lines which do not match the document, so code formatters will not work on them.

Use the --group-marker option to set a marker for this particular command which will work as well as all. For example, use --group-marker="type-check" to group code blocks which come between comments matching group doccmd[type-check]: start and group doccmd[type-check]: end.

Using groups with formatters

By default, code blocks in groups will be separated by newlines in the temporary file created. This means that line numbers from the original document match the line numbers in the temporary file, and error messages will have correct line numbers. Some tools, such as formatters, may not work well with this separation. To have just one newline between code blocks in a group, use the --no-pad-groups option. If you then want to add extra padding to the code blocks in a group, add invisible code blocks to the document. Make sure that the language of the invisible code block is the same as the --language option given to doccmd.

For example:

• reStructuredText (.rst)

.. invisible-code-block: java

• Markdown (.md)

<!-- invisible-code-block: java

-->

Full documentation

See the full documentation.