Expand description
Command Line Argument Parser for Rust
Quick Links:
- Derive [tutorial][_derive::_tutorial] and [reference][_derive]
- Builder [tutorial][_tutorial] and reference
- [Cookbook][_cookbook]
- [FAQ][_faq]
- Discussions
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 1.56.1)
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][_features])
Then define your CLI in main.rs
:
use clap::Parser;
/// Simple program to greet a person
#[derive(Parser, Debug)]
#[clap(author, version, about, long_about = None)]
struct Args {
/// Name of the person to greet
#[clap(short, long, value_parser)]
name: String,
/// Number of times to greet
#[clap(short, long, value_parser, 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
clap [..]
A simple to use, efficient, and full-featured Command Line Argument Parser
USAGE:
demo[EXE] [OPTIONS] --name <NAME>
OPTIONS:
-c, --count <COUNT> Number of times to greet [default: 1]
-h, --help Print help information
-n, --name <NAME> Name of the person to greet
-V, --version Print version information
$ demo --name Me
Hello Me!
(version number and .exe
extension on windows replaced by placeholders)
See also the derive [tutorial][_derive::_tutorial] and [reference][_derive]
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:
Re-exports
Modules
Macros
Requires
cargo
feature flag to be enabled.Select a
ValueParser
implementation from the intended typeStructs
The abstract representation of a command line argument. Used to set all the options and
relationships that define a valid argument for the program.
Container for parse results.
Iterate over indices for where an argument appeared when parsing, via
ArgMatches::indices_of
Deprecated, replaced with
ArgMatches::get_many()
A possible value of an argument.
Deprecated, replaced with
ArgMatches::get_many()
Enums
Application level settings, which affect how
Command
operatesBehavior of arguments when they are encountered while parsing
Various settings that apply to arguments and may be set, unset, and checked via getter/setter
methods
Arg::setting
, Arg::unset_setting
, and Arg::is_set
. This is what the
Arg
methods which accept a bool
use internally.Represents the color preferences for program output
Command line argument parser kind of error
Provide shell with hint on how to complete an argument.
Origin of the argument’s value
Traits
Parse arguments into enums.
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
Build a command-line interface.