eof-fixer 0.3.2

A command-line tool that ensures all your text files end with exactly one newline character

End Of File Fixer

A command-line tool that ensures all your text files end with exactly one newline character. This tool helps maintain consistent file formatting across your codebase by automatically adding or removing trailing newlines as needed.

Why This Matters

Many POSIX systems expect text files to end with a newline character. Having consistent line endings:

• Prevents spurious diffs in version control
• Ensures proper concatenation of files
• Satisfies POSIX compliance
• Improves readability in terminal environments

Features

• Automatically adds a newline to files that don't end with one
• Removes excess trailing newlines from files that have too many
• Respects .gitignore patterns to avoid processing unwanted files
• Works with all text file types
• Cross-platform compatibility (Windows, macOS, Linux)
• Dry-run mode to preview changes before applying them

Installation

Using uv

uv add eof-fixer

Using pip

pip install eof-fixer

Usage

Basic Usage

To fix all files in the current directory and subdirectories:

eof-fixer .

To check which files would be modified without making changes:

eof-fixer . --check

How It Works

The eof-fixer processes files in the following way:

1. Files with no trailing newline: Adds exactly one newline at the end
2. Files with exactly one trailing newline: Leaves unchanged
3. Files with multiple trailing newlines: Truncates to exactly one newline
4. Empty files: Left unchanged

Examples

Original File Content	After Processing
hello world	hello world\n
hello world\n	hello world\n
hello world\n\n\n	hello world\n
`` (empty file)	`` (unchanged)

Note on line endings: when appending a missing terminator, eof-fixer always writes an LF (\n), regardless of the existing line-ending style of the file. A file that otherwise uses CRLF or CR will end up with a mixed terminator on its last line. This matches the behavior of pre-commit's end-of-file-fixer. Files that already end with a single CRLF, CR, or LF are left untouched.

Configuration

The tool automatically respects patterns in your .gitignore file, so it won't process files that are ignored by Git. Only the .gitignore at the root of the supplied path is consulted; nested .gitignore files in subdirectories are not read. Additionally, it always ignores:

• .git directories
• .cache and .uv-cache directories (used by uv)
• Binary files (detected by null bytes in the first 1024 bytes)

Exit Codes

• 0: No files needed fixing.
• 1: At least one file needed fixing. In --check mode no changes are written; in the default (fix) mode the files have been rewritten in place. The non-zero exit in fix mode is intentional so the tool can be used as a pre-commit or CI gate — re-run after the fix and the exit code returns to 0.

Development

Prerequisites

• uv for dependency management

Setup

# Clone the repository
git clone https://github.com/modern-python/eof-fixer.git
cd eof-fixer

# Install dependencies
just install

Running Tests

# Run tests
just test

Linting

# Run linting and formatting
just lint

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

1. Fork the repository
2. Create your feature branch (git checkout -b feature/AmazingFeature)
3. Commit your changes (git commit -m 'Add some amazing feature')
4. Push to the branch (git push origin feature/AmazingFeature)
5. Open a Pull Request

License

This project is licensed under the MIT License - see the LICENSE file for details.

Acknowledgments

The core file-fixing logic in this project is derived from the end-of-file-fixer hook in pre-commit/pre-commit-hooks, which is also distributed under the MIT License. This project repackages that logic as a standalone CLI with .gitignore-aware directory traversal so it can be used outside of the pre-commit framework.

Related Projects

• pre-commit - A framework for managing and maintaining multi-language pre-commit hooks
• editorconfig - Helps maintain consistent coding styles across different editors and IDEs

Part of modern-python

Browse the full list of templates and libraries in modern-python — see the org profile for the categorized index.