grrs

A tiny grep -n clone written in Rust. It scans a file for a substring pattern and prints every matching line prefixed with its 1-based line number.

Features

• Command-line interface powered by clap
• Shared search logic exposed through a search_file function in the library crate
• Case-insensitive (-i/--ignore-case) and inverted (-v/--invert-match) filtering
• Helpful error messages when files cannot be read
• Integration tests using assert_cmd, predicates, and tempfile

Prerequisites

• Rust toolchain (cargo + rustc). Install via rustup.

Usage

cargo run -- [OPTIONS] <pattern> <path>

Options

• -i, --ignore-case – match without case sensitivity
• -v, --invert-match – print only the lines that do not contain the pattern

Try it with this repository's README

cargo run -- --ignore-case readme README.md

Invert the match (prints non-matching lines):

cargo run -- --invert-match readme README.md

Testing

cargo test

This runs unit tests (when present) and the CLI integration test in tests/cli.rs.

Next Steps

Ideas for future improvements:

• Regex-based searches (e.g., using the regex crate)
• Reading from stdin and searching multiple files recursively
• Additional flags such as --context, --count, or recursive directory walking