getopt-rs

A Rust wrapper for the Unix getopt function for parsing command line arguments.

Installation

Add this to your Cargo.toml:

[dependencies]
getopt-rs = "0.1.0"

Usage

This library provides a safe Rust interface to the Unix getopt function for parsing command-line options. It supports both simple flags and options with values.

Basic Usage

use getopt_rs::Getopt;

fn main() {
    // assuming
    // program -a -b value -c file1 file2
    let args: Vec<String> = std::env::args().collect();
    let getopt = Getopt::new(&args, "ab:c", true);

    // Iterate over the options
    for opt in &getopt {
        match opt.val() {
            'a' => println!("Flag -a was set"),
            'b' => println!("Option -b had value: {}", opt.arg().unwrap()),
            'c' => println!("Flag -c was set"),
            '?' => println!("Unknown option: -{}", opt.erropt().unwrap()),
            _ => unreachable!()
        }
    }

    // Process remaining arguments
    println!("Remaining arguments: {:?}", getopt.remaining());
}

Option String Format

The option string follows Unix getopt conventions:

• Must be single byte characters
• Single letters represent flags (e.g. "ab" allows -a and -b flags)
• Letters followed by : represent options that take values (e.g. "a:b:" means -a value -b value)
• Is passed directly to the system's libc getopt() function permitting any platform specifc extensions

Error Handling

The library handles two types of errors:

• Unknown options: Returns an Opt with val() == '?' and erropt() containing the invalid option
• Missing arguments:
  • If optstring starts with ':': Returns an Opt with val() == ':' and erropt() containing the option
  • Otherwise: Returns an Opt with val() == '?' and erropt() containing the option

Option Comparison

Options can be directly compared with characters:

use getopt_rs::Getopt;

let args: Vec<String> = std::env::args().collect();
let getopt = Getopt::new(&args, "a", true);
if let Some(opt) = getopt.into_iter().next() {
    assert!(opt == 'a');
}

License

BSD-2-Clause

Copyright 2025 Latigo LLC

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS “AS IS” AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.