Expand description
Command Line Argument Parser for Rust
Quick Links:
Aspirations
- Out of the box, users get a polished CLI experience
- Including common argument behavior, help generation, suggested fixes for users, colored output, shell completions, etc
- Flexible enough to port your existing CLI interface
- However, we won’t necessarily streamline support for each use case
- Reasonable parse performance
- Resilient maintainership, including
- Willing to break compatibility rather than batching up breaking changes in large releases
- Leverage feature flags to keep to one active branch
- Being under WG-CLI to increase the bus factor
- We follow semver and will wait about 6-9 months between major breaking changes
- We will support the last two minor Rust releases (MSRV, currently 1.64.0)
While these aspirations can be at odds with fast build times and low binary size, we will still strive to keep these reasonable for the flexibility you get. Check out the argparse-benchmarks for CLI parsers optimized for other use cases.
Example
Run
$ cargo add clap --features derive
(See also feature flag reference)
Then define your CLI in main.rs
:
use clap::Parser;
/// Simple program to greet a person
#[derive(Parser, Debug)]
#[command(author, version, about, long_about = None)]
struct Args {
/// Name of the person to greet
#[arg(short, long)]
name: String,
/// Number of times to greet
#[arg(short, long, default_value_t = 1)]
count: u8,
}
fn main() {
let args = Args::parse();
for _ in 0..args.count {
println!("Hello {}!", args.name)
}
}
And try it out:
$ demo --help
A simple to use, efficient, and full-featured Command Line Argument Parser
Usage: demo[EXE] [OPTIONS] --name <NAME>
Options:
-n, --name <NAME> Name of the person to greet
-c, --count <COUNT> Number of times to greet [default: 1]
-h, --help Print help
-V, --version Print version
$ demo --name Me
Hello Me!
(version number and .exe
extension on windows replaced by placeholders)
See also the derive tutorial and reference
Related Projects
Augment clap:
- wild for supporting wildcards (
*
) on Windows like you do Linux - argfile for loading additional arguments from a file (aka response files)
- shadow-rs for generating
Command::long_version
- clap_mangen for generating man page source (roff)
- clap_complete for shell completion support
CLI Helpers
Testing
trycmd
: Bulk snapshot testingsnapbox
: Specialized snapshot testingassert_cmd
andassert_fs
: Customized testing
Documentation:
Modules
- _cookbook
unstable-doc
Documentation: Cookbook - _derive
unstable-doc
Documentation: Derive Reference - _faq
unstable-doc
Documentation: FAQ - _features
unstable-doc
Documentation: Feature Flags - _tutorial
unstable-doc
Documentation: Builder Tutorial - Error reporting
Command
line argument parser
Macros
- Create an
Arg
from a usage string. - command
cargo
Allows you to build theCommand
instance from your Cargo.toml at compile time. - crate_authors
cargo
Allows you to pull the authors for the command from your Cargo.toml at compile time in the form:"author1 lastname <author1@example.com>:author2 lastname <author2@example.com>"
- crate_description
cargo
Allows you to pull the description from your Cargo.toml at compile time. - crate_name
cargo
Allows you to pull the name from your Cargo.toml at compile time. - crate_version
cargo
Allows you to pull the version from your Cargo.toml at compile time asMAJOR.MINOR.PATCH_PKGVERSION_PRE
- Select a
ValueParser
implementation from the intended type
Structs
- The abstract representation of a command line argument. Used to set all the options and relationships that define a valid argument for the program.
- Family of related arguments.
- Container for parse results.
- Build a command-line interface.
Enums
- Behavior of arguments when they are encountered while parsing
- Represents the color preferences for program output
- Provide shell with hint on how to complete an argument.
Traits
- Parse a set of arguments into a user-defined container.
- Create a
Command
relevant for a user-defined container. - Converts an instance of
ArgMatches
to a user-defined container. - Parse command-line arguments into
Self
. - Parse a sub-command into a user-defined enum.
- Parse arguments into enums.
Type Definitions
- Command Line Argument Parser Error