grepme

A small grep-like command-line tool written in Rust, built as part of working through the Rust Book's grepme project and extended with extra features such as full regex support (via fancy-regex), automatic directory recursion, colored output, and writing results to a file.

Features

• Regex search - queries are compiled as regular expressions (including lookaround, backreferences, etc. thanks to fancy-regex), so you can pass either a plain string or a full pattern (test your syntax).
• Recursive directory search - pass a folder as a target and every file inside it (recursively) is searched automatically.
• Multiple targets - search any number of files and/or folders in a single invocation.
• Case-insensitive search - via a flag or the IGNORE_CASE environment variable.
• Colored output - matches are highlighted in the terminal using colored. Color is automatically disabled when writing output to a file.
• Symlinks are skipped (not followed), and I/O errors are reported as non-blocking warnings so the rest of the search can continue.
• Output to file - redirect results to a file instead of stdout, ignores ouput file in search.

Installation

Clone the repository and build with Cargo:

git clone <this-repo-url>
cd grepme
cargo build --release

The compiled binary will be available at target/release/grepme.

Usage

grepme [arguments] query [paths/glob]

• query - a plain string or a quoted regex pattern to search for.
• paths/glob - one or more files or directories to search. Directories are searched recursively.

Arguments

Environment variables

• IGNORE_CASE - if set to true, enables case-insensitive search by default. This can still be overridden by explicitly passing -i/--ignore-case.

Examples

Search for the literal string TODO in a single file:

grepme duck src/main.rs

Recursively search an entire directory, case-insensitively:

grepme -i "duck" src/

Search with a regex pattern and write the results to a file:

grepme -o results.txt "(?i)duck" src/

Search multiple files/folders in one command:

grepme "duck" src/ Cargo.toml

Project structure

src/
  main.rs      # CLI entry point: argument handling, running the search, printing output
  config.rs    # Config parsing (Config::build) and the help text
  search.rs    # Core search logic (search_valid_files)
  targets.rs   # Expands file/folder arguments into a flat list of files to search

• Config::build (in config.rs) parses the raw CLI arguments into a Config struct, handling flags, the query, and target paths.
• targets::expand_to_files (in targets.rs) walks the given paths, recursing into directories, skipping symlinks, and avoiding re-reading the output file if one is specified.
• search::search_valid_files (in search.rs) runs the compiled regex against each line of a file's contents and returns the matching line numbers and text.
• main.rs wires these pieces together: it builds the config, expands targets, compiles the regex, searches each file, and prints or writes the formatted results.

Running tests

cargo test

License

Licensed under either of the MIT license or the Apache License, Version 2.0, at your option.