rgx-cli 0.5.1

A terminal regex debugger with real-time matching, capture group highlighting, and plain-English explanations
Documentation

rgx

regex101, but in your terminal

CI Crates.io Downloads License

A terminal regex debugger with real-time matching, capture group highlighting, and plain-English explanations. Written in Rust.

demo

Press F1 in the app for a multi-page cheat sheet with keyboard shortcuts, regex syntax, and engine-specific features.

Features

  • Real-time matching — matches update on every keystroke
  • Syntax-highlighted pattern input — AST-based coloring for groups, quantifiers, character classes, anchors, and escapes
  • 3 regex engines — Rust regex (default), fancy-regex (lookaround/backrefs), PCRE2 (full features)
  • Capture group highlighting — distinct colors per group, nested group support
  • Plain-English explanations — walks the regex AST to generate human-readable breakdowns
  • Replace/substitution mode — live preview with $1, ${name}, $0/$& syntax
  • Match detail + clipboard — navigate matches/captures with Up/Down, copy with Ctrl+Y
  • Pattern history + undo — Ctrl+Z/Ctrl+Shift+Z undo/redo, Alt+Up/Down browse history
  • Context-sensitive cheat sheet — F1 multi-page help: shortcuts, regex syntax, engine-specific features
  • Whitespace visualization — toggle with Ctrl+W to show spaces as ·, newlines as ↵, tabs as →
  • Mouse support — click to focus/position cursor, scroll to navigate panels
  • Engine selector — switch engines with Ctrl+E, see where behavior differs
  • Regex flags — toggle case-insensitive, multiline, dotall, unicode, extended
  • Stdin pipe support — echo "test string" | rgx '\d+'
  • Cross-platform — Linux, macOS, Windows

Installation

From crates.io

cargo install rgx-cli

From prebuilt binaries

Download from GitHub Releases.

Shell installer

curl --proto '=https' --tlsv1.2 -LsSf https://github.com/brevity1swos/rgx/releases/latest/download/rgx-installer.sh | sh

Homebrew

brew install brevity1swos/tap/rgx

From source

git clone https://github.com/brevity1swos/rgx.git
cd rgx
cargo install --path .

Without PCRE2 (zero C dependencies)

cargo install rgx-cli --no-default-features

Usage

# Interactive mode
rgx

# Start with a pattern
rgx '\d{3}-\d{3}-\d{4}'

# Pipe text from stdin
echo "Call 555-123-4567 or 555-987-6543" | rgx '\d{3}-\d{3}-\d{4}'

# Use a specific engine
rgx --engine fancy '\w+(?=@)'

# With flags
rgx -i 'hello'

# With replacement template
rgx -r '$2/$1' '(\w+)@(\w+)'

Keyboard Shortcuts

Key Action
Tab Cycle focus: pattern / test / replace / matches / explanation
Up/Down Scroll panel / move cursor / select match
Enter Insert newline (test string)
Ctrl+E Cycle regex engine
Ctrl+Z Undo
Ctrl+Shift+Z Redo
Ctrl+Y Copy selected match to clipboard
Ctrl+W Toggle whitespace visualization
Ctrl+Left/Right Move cursor by word
Alt+Up/Down Browse pattern history
Alt+i/m/s/u/x Toggle flags (case, multiline, dotall, unicode, extended)
F1 Show help (Left/Right to page through)
Mouse click Focus panel and position cursor
Mouse scroll Scroll panel under cursor
Esc Quit

Engines

Engine Features Dependencies
Rust regex (default) Fast, linear time, Unicode Pure Rust
fancy-regex + lookaround, backreferences Pure Rust
PCRE2 + possessive quantifiers, recursion, conditionals Requires libpcre2

Comparison

Feature rgx regex-tui rexi regex101.com
Real-time matching Yes Yes Yes Yes
Multiple engines 3 2 1 8
Capture group highlighting Yes No No Yes
Plain-English explanations Yes No No Yes
Replace/substitution Yes No No Yes
Match clipboard copy Yes No No Yes
Undo/redo Yes No No Yes
Whitespace visualization Yes Yes No No
Mouse support Yes No No N/A
Regex flags toggle Yes Yes No Yes
Stdin pipe support Yes Yes Yes No
Offline / no browser Yes Yes Yes No
Cross-platform binary Yes Yes No N/A

Configuration

rgx looks for a config file at ~/.config/rgx/config.toml:

default_engine = "rust"  # "rust", "fancy", or "pcre2"

Contributing

See CONTRIBUTING.md for details.

License

Licensed under either of

at your option.