d2o

A high-performance, pure Rust rewrite of h2o - a CLI tool that extracts command-line options from help text and man pages, then exports them as shell completion scripts or JSON.

Installation

From Source

cd /home/muntasir/projects/d2o
cargo build --release
./target/release/d2o --help

The release binary will be at target/release/d2o

Pre-compiled Binary

Copy the binary to your PATH:

cp target/release/d2o ~/.local/bin/

Using Cargo

cargo install d2o

Using cargo-binstall

cargo binstall d2o

Completions are also available for bash, zsh, fish, powershell, elvish and nushell:

d2o --completions <shell> # Replace <shell> with your shell name

Manpages are in tarballs and zips in releases.

Usage

Generate shell completion

# Generate fish completion script from `man ls` or `ls --help`
d2o --command ls --format fish > ls.fish

# Generate zsh completion script
d2o --command git --format zsh > git.zsh

# Generate bash completion script (plain options only)
d2o --command docker --format bash > docker.bash

# Generate bash completion script compatible with bash-completion (includes descriptions)
d2o --command docker --format bash --bash-completion-compat > docker.bash

Export as JSON

# Export CLI info as JSON
d2o --command ls --format json

# Pretty-print JSON output
d2o --command curl --format json | jq .

Parse local file

# Save man page to file first
man grep | col -bx > grep.txt

# Parse from file
d2o --file grep.txt --format fish > grep.fish

Advanced options

# Skip man page lookup (use --help only)
d2o --command cargo --skip-man --format json

# List subcommands
d2o --command git --list-subcommands

# Extract subcommand options
d2o --subcommand git-log --format fish

# Preprocess only (debug option splitting)
d2o --command ls --preprocess-only

# Scan deeper for nested subcommands
d2o --command docker --depth 2 --format json

Building

# Debug build
cargo build

# Release build with optimizations
cargo build --release

Running with verbose output

RUST_LOG=debug ./target/release/d2o --command ls --format json

Known Limitations

• Subcommand depth must be specified (default: 1 level)
• Some highly unusual help text formats may not parse perfectly
• Unicode box-drawing characters in help text are converted to ASCII

Related Projects

• parse-help

License

MIT - See LICENSE file

Contributing

Contributions welcome! Areas for improvement:

• Performance optimizations
• Additional help text format support
• More comprehensive testing
• Documentation