LineGuard

A fast and reliable file linter that ensures proper line endings and clean formatting.

Features

• ✅ Newline Ending Check: Ensures files end with exactly one newline character
• ✅ Trailing Space Detection: Identifies and reports trailing whitespace at line ends
• 🚀 High Performance: Parallel file processing with progress indicators
• 🎨 Multiple Output Formats: Human-readable (with colors), JSON, and GitHub Actions formats
• 🔧 Configurable: Flexible configuration via CLI flags or .lineguardrc files
• 🔄 Auto-fix: Automatically fix issues with --fix flag
• 📁 Smart File Discovery: Glob patterns, recursive directory scanning, stdin support
• 🎯 Selective Checks: Disable specific checks via CLI flags
• 💾 Memory Efficient: Streaming support for large files (>10MB)
• 🛡️ Robust Error Handling: Graceful handling of permission errors
• 🔍 Binary File Detection: Automatically skips binary files
• 👁️ Hidden Files: Checks hidden files by default (use --no-hidden to skip)
• 🚫 Ignore Patterns: Skip files/directories with glob patterns
• 📝 File Extension Filtering: Check only specific file types
• 🔀 Git Integration: Check only files changed between commits

Installation

From Crates.io

cargo install lineguard

From GitHub Releases

Download pre-built binaries from the latest release:

# Linux/macOS
curl -L https://github.com/hydai/lineguard/releases/latest/download/lineguard-{VERSION}-{TARGET}.tar.gz | tar xz
sudo mv lineguard /usr/local/bin/

# Windows
# Download the .zip file and extract lineguard.exe to a directory in your PATH

From Source

git clone https://github.com/hydai/lineguard
cd lineguard
cargo install --path .

Usage

Basic Usage

# Check a single file
lineguard main.rs

# Check multiple files
lineguard src/main.rs src/lib.rs

# Check with glob pattern
lineguard "src/**/*.rs"

# Check all files in directory
lineguard .

Command-Line Options

lineguard [OPTIONS] [FILES...]

Arguments:
  [FILES...]  Files or directories to check

Options:
  -r, --recursive              Recursively check directories
  -f, --format <FORMAT>        Output format [default: human] [possible values: human, json, github]
  -q, --quiet                  Suppress non-error output
  -v, --verbose                Show detailed information
      --no-color               Disable colored output
  -c, --config <CONFIG>        Path to configuration file
      --stdin                  Read file paths from stdin
      --ignore <IGNORE>        Ignore files matching pattern (can be used multiple times)
      --extensions <EXTENSIONS> File extensions to check (comma-separated)
      --no-hidden              Skip hidden files (files starting with .)
      --no-newline-check       Disable newline ending check
      --no-trailing-space      Disable trailing space check
      --fix                    Automatically fix issues
      --dry-run                Show what would be fixed without modifying files
      --from <FROM>            Check files changed since this commit (Git only)
      --to <TO>                Check files changed until this commit (Git only, default: HEAD)
  -h, --help                   Print help
  -V, --version                Print version

Advanced Usage

# Fix issues automatically
lineguard --fix src/

# Preview fixes without applying
lineguard --fix --dry-run src/

# Ignore specific patterns
lineguard --ignore "*.generated.rs" --ignore "**/target/**" .

# Check only specific file types
lineguard --extensions rs,toml .

# Use custom config file
lineguard --config path/to/.lineguardrc src/

# Disable specific checks
lineguard --no-trailing-space src/  # Only check newlines
lineguard --no-newline-check src/   # Only check trailing spaces

# Pipe files from other commands
find . -name "*.rs" | lineguard --stdin

# Check files changed in the last commit
lineguard --from HEAD~1 .

# Check files changed between specific commits
lineguard --from abc123 --to def456 .

# Check files changed since a tag
lineguard --from v1.0.0 src/

# Combine with other options
lineguard --from main --fix --format json .

Output Examples

Human-Readable Format (Default)

✗ src/main.rs
  - Missing newline at end of file
  - Line 45: Trailing spaces found

✓ src/lib.rs

Summary: 1 file with issues, 2 total issues found

JSON Format

lineguard --format json src/

{
  "files_checked": 3,
  "files_with_issues": 1,
  "total_issues": 2,
  "issues": [
    {
      "file": "src/main.rs",
      "issues": [
        {
          "type": "missing_newline",
          "line": null,
          "message": "Missing newline at end of file"
        },
        {
          "type": "trailing_space",
          "line": 45,
          "message": "Trailing spaces found"
        }
      ]
    }
  ],
  "errors": [
    {
      "file": "src/protected.rs",
      "error": "Permission denied (os error 13)"
    }
  ]
}

GitHub Actions Format

lineguard --format github src/

Configuration File

LineGuard supports configuration files to customize its behavior. Create a .lineguardrc file in your project root (see .lineguardrc.example for reference):

# .lineguardrc
[checks]
newline_ending = true      # Check for proper newline at end of file
trailing_spaces = true     # Check for trailing spaces

# Ignore patterns (glob format)
ignore_patterns = [
    "**/target/**",
    "**/.git/**",
    "**/node_modules/**",
    "*.generated.*",
]

# File extensions to check (default: all text files)
file_extensions = [
    "rs", "toml", "md", "txt",
    "js", "ts", "jsx", "tsx",
    "py", "go", "java", "c", "cpp", "h", "hpp",
    "yml", "yaml", "json", "xml",
]

Configuration files are searched in the following order:

1. Path specified with --config flag
2. .lineguardrc in the current directory
3. .lineguardrc in parent directories (up to the root)

CLI flags always override configuration file settings.

Exit Codes

• 0 - Success, no issues found
• 1 - Issues found in checked files
• 2 - Error in command-line arguments
• 3 - File access or I/O error
• 4 - Configuration error

Development

This project follows strict Test-Driven Development (TDD) practices. See IMPLEMENTATION_PLAN.md for development guidelines.

Building

cargo build

Testing

cargo test

Code Quality

cargo fmt --all -- --check  # Check code formatting
cargo fmt --all             # Auto-format code
cargo clippy --all-targets --all-features -- -D warnings  # Run linter

License

Licensed under the Apache License, Version 2.0. See LICENSE for details.

Contributing

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