rgrep 🦀

Copyright (c) 2026 Francesco Tinti francesco.tinti@activemind.it AI-assisted port — Architect: Claude Opus 4.7 (Anthropic) · Implementer: Gemini Antigravity (Google)

rgrep is a modern, modular, and blazingly fast clone of the original GNU grep, completely rewritten in Rust.

This project started as an educational experiment to translate a minimal 30-line C implementation of grep into Rust, and iteratively evolved into a 100% compliant, feature-rich text search engine capable of matching almost all major GNU grep functionalities.

🚀 Features

rgrep uses Rust's heavily optimized regex and globset crates to provide lightning-fast text processing, alongside modern features like memory-mapping and robust file-system traversal.

Supported GNU Grep Flags:

Pattern & Regex Control

• -e, --regexp: Specify multiple patterns (OR logic).
• -f, --file: Read patterns line by line from a file.
• -F, --fixed-strings: Interpret patterns as literal strings instead of Regex.
• -i, --ignore-case: Ignore case distinctions.
• --no-ignore-case: Do not ignore case distinctions.
• -w, --word-regexp: Match whole words only.
• -x, --line-regexp: Match exactly the whole line.
• -E, -G, -P: Compatibility stubs for Extended, Basic, and Perl regex.

Context Control

• -A, --after-context=NUM: Print NUM lines of trailing context.
• -B, --before-context=NUM: Print NUM lines of leading context.
• -C, --context=NUM: Print NUM lines of output context.
• --group-separator=SEP: Use custom separator between context blocks (default: --).
• --no-group-separator: Do not use a group separator.

File & Directory Traversal

• -r, --recursive: Read all files under each directory, recursively.
• -R, --dereference-recursive: Recursive search, following symbolic links.
• -d, --directories=ACTION: Handle directories (read, skip).
• -D, --devices=ACTION: Handle devices (read, skip).
• --include=GLOB: Search only files matching GLOB.
• --exclude=GLOB: Skip files matching GLOB.
• --exclude-dir=GLOB: Exclude entire directories matching GLOB.
• --exclude-from=FILE: Read exclude globs from a file.

Output Formatting

• -n, --line-number: Prefix each line with its 1-based line number.
• -b, --byte-offset: Print the 0-based byte offset of each line.
• -H, --with-filename: Print the file name for each match.
• -h, --no-filename: Suppress the prefixing of file names.
• -l, --files-with-matches: Print only names of FILEs containing matches.
• -L, --files-without-match: Print only names of FILEs containing no matches.
• -o, --only-matching: Print only the matched parts of a line.
• -c, --count: Print a count of matching lines for each file.
• -T, --initial-tab: Line up tabs for easier reading.
• --color: Highlight matches and file names using ANSI colors.

Low Level & Binary

• -z, --null-data: Read lines separated by a zero byte (NULL) instead of newline.
• -Z, --null: Output a zero byte after the file name instead of a colon.
• -a, --text: Process a binary file as if it were text.
• -U, --binary: Treat the files as binary.
• --binary-files=TYPE: Treat binary files as TYPE.

Optimizations & Limits

• -m, --max-count=NUM: Stop reading a file after NUM matching lines.
• --mmap: Use low-level OS memory-mapped I/O to read input files (can improve performance on large files).
• --line-buffered: Flush output on every line.
• -q, --quiet, --silent: Exit immediately with zero status if any match is found.
• -s, --no-messages: Suppress error messages about nonexistent or unreadable files.
• --label=LABEL: Use LABEL as the standard input file name prefix.

📦 Installation

To build rgrep from source, ensure you have the Rust toolchain installed.

# Clone the repository
git clone https://github.com/francescotinti/rgrep.git
cd rgrep

# Build for release
cargo build --release

# The compiled binary will be at:
# target/release/rgrep

You can install it directly into your local cargo path:

cargo install --path .

🛠️ Usage Example

Search recursively in the current directory for the exact word "TODO", ignoring case, printing line numbers, showing 2 lines of context, and highlighting matches in color:

rgrep -r -w -i -n -C 2 --color "TODO" .

Search using memory-mapping for maximum speed and stop after 5 matches:

rgrep --mmap -m 5 "foo" large_file.log

📜 License

This project is open-source and built for educational and practical usage.