Cliffy

Commands

The command class is used to create main and sub commands. All methods from the command class are chainable and returns the current command instance. There are only two exceptions:

  • The .command() method returns the new created sub command, so you can add options, argument, environment variables and types to your sub commands in a chainable way.
  • The .reset() method returns the main command from your current command chain.

Name

With the .name() method you can define the name of your main command. The name should match the name of your program. It is displayed in the auto generated help and used for shell completions.

Version

With the .version() method you can define the version of your cli. The version is displayed in the auto generated help and the version option.

Description

The .description() method adds a description for the command that will be displayed in the auto generated help. If the help options is called with the short flag -h only the first line is displayed. If called with the long name --help, the full description is displayed.

For better multiline formatting, unnecessary indentations and empty leading and trailing lines will be automatically removed.

For example, following description:

new Command()
  .description(`
    This is a multiline description.
      The indentation of this line will be preserved.
  `);Copy

is formatted as follows:

This is a multiline description.
  The indentation of this line will be preserved.Copy

Usage

With the .usage() method you can override the usage text that is displayed at the top of the auto generated help which defaults to the command arguments. The usage is always prefixed with the command name.

import { Command } from "https://deno.land/x/cliffy@v0.24.3/command/mod.ts";

new Command()
  .name("script-runner")
  .description("Simple script runner.")
  .usage("[options] [script] [script options]")
  .parse(Deno.args);Copy

Arguments

You can use the .arguments() method to specify the arguments for your commands. Angled brackets (e.g. <required>) indicate required input and square brackets (e.g. [optional]) indicate optional input. A required input cannot be defined after an optional input.

Arguments can be also defined with the .command() method. You can read more about the .command() method here.

Optionally you can define types and completions for your arguments. If no type is specified the type defaults to string.

import { Command } from "https://deno.land/x/cliffy@v0.24.3/command/mod.ts";

const { args } = await new Command()
  .arguments("<input> [output:string]")
  .parse(Deno.args);Copy
$ deno run https://deno.land/x/cliffy@v0.24.3/examples/command/arguments_syntax.ts
Error: Missing argument(s): inputCopy

Variadic arguments

The last argument of a command can be variadic. To make an argument variadic you can append or perpend ... to the argument name. The variadic argument is passed to the action handler as an array.

import { Command } from "https://deno.land/x/cliffy@v0.24.3/command/mod.ts";

const { args } = await new Command()
  .description("Remove directories.")
  .arguments("<dirs...>")
  .parse(Deno.args);

const dirs = args[0];

for (const dir of dirs) {
  console.log("rmdir %s", dir);
}Copy
$ deno run https://deno.land/x/cliffy@v0.24.3/examples/command/variadic_arguments.ts dir1 dir2 dir3  
rmdir dir1  
rmdir dir2  
rmdir dir3Copy

Option

Options can be added with the .option() method. The first two arguments of the method are required. With the first argument you specify the flags and arguments of your option. The second argument is the description and with the third argument you can set some option specific settings.

Optionally you can define types and completions for the arguments of the option. If no type is specified the type defaults to string. If no argument is specified, the type defaults to true. You can read more about options here.

import { Command } from "https://deno.land/x/cliffy@v0.24.3/command/mod.ts";

const { args } = await new Command()
  .option("-f, --file <path:string>", "Force option.")
  .parse(Deno.args);Copy

Action handler

The action handler is called when the command is executed and can be registered with the .action() method. The first arguments is the options object, which contains all options and environment variables, followed by all arguments, in the same order in which they were defined with the .arguments() method. Options and arguments will be automatically typed by infering the types and names of all options, arguments and environment variables 🚀.

import { Command } from "https://deno.land/x/cliffy@v0.24.3/command/mod.ts";

await new Command()
  .name("rm")
  .description("Remove directory.")
  .option("-r, --recursive", "Remove directory recursively.")
  .arguments("<dir>")
  .action(({ recursive }, dir: string) => {
    console.log("remove " + dir + (recursive ? " recursively" : ""));
  })
  .parse(Deno.args);Copy
$ deno run https://deno.land/x/cliffy@v0.24.3/examples/command/action_handler.ts rm dir
remove dirCopy

Stop early

If enabled, all arguments starting from the first non option argument will be interpreted as raw argument.

import { Command } from "https://deno.land/x/cliffy@v0.24.3/command/mod.ts";

await new Command()
  .option("-d, --debug-level <level:string>", "Debug level.")
  .arguments("[script] [args...]")
  .stopEarly() // <-- enable stop early
  // deno-lint-ignore no-explicit-any
  .action((options: any, script: string, args: Array<string>) => {
    console.log("options:", options);
    console.log("script:", script);
    console.log("args:", args);
  })
  .parse(Deno.args);Copy
$ deno run https://deno.land/x/cliffy@v0.24.3/examples/command/stop_early.ts -d warning server -p 80
options: { debugLevel: "warning" }
script: server
args: [ "-p", "80" ]Copy

Sub commands

With the .command() method you can add and nest sub commands as many you want. The first argument is the command name with optional arguments. The seconds argument is optional and can be either the description of the command or an instance of Command. You can read more about sub commands here.

import { Command } from "https://deno.land/x/cliffy@v0.24.3/command/mod.ts";

await new Command()
  .command("foo [val:string]")
  .description("Foo command.")
  .action(() => console.log("Foo action."))
  .command("bar [val:string]", "Foo command.")
  .action(() => console.log("Bar action."))
  .parse(Deno.args);Copy

Global commands

To share commands with sub commands you can use the .global() method.

import { Command } from "https://deno.land/x/cliffy@v0.24.3/command/mod.ts";

await new Command()
  .command("global [val:string]", "global ...")
  .global()
  .action(console.log)
  .command(
    "command1",
    new Command()
      .description("Some sub command.")
      .command(
        "command2",
        new Command()
          .description("Some nested sub command."),
      ),
  )
  .parse(Deno.args);Copy
$ deno run https://deno.land/x/cliffy@v0.24.3/examples/command/global_commands.ts command1 command2 global test
{} testCopy

Hidden commands

To exclude sub commands from the auto generated help and shell completions you can use the .hidden() method.

import { Command } from "https://deno.land/x/cliffy@v0.24.3/command/mod.ts";

await new Command()
  .command("debug", "Some internal debugging command.")
  .hidden()
  .parse(Deno.args);Copy
$ deno run https://deno.land/x/cliffy@v0.24.3/examples/command/hidden_commands.ts -hCopy

Parse

The .parse() method processes all arguments, leaving any options and environment variables consumed by the command in the options object, all arguments in the args array and all arguments defined after the double dash (--) in the literal array.

For all unknown or invalid options, arguments and types the command will throw an error and exit the program with Deno.exit(1). Read more about error handling here.

The parse method accepts optionally as first argument an array of command-line arguments that should be consumed. By default Deno.args is used.

import { Command } from "https://deno.land/x/cliffy@v0.20.1/command/mod.ts";

const { args, options, literal, cmd } = new Command()
  .option("--debug", "Enable debugging.")
  .arguments("<input:string>")
  .env("DEBUG", "Enable debugging.")
  .parse();Copy

All types and names for options, arguments and environment variables are automatically inferred and properly typed. If the command has sub commands, options and arguments will be of type Record<string, unknown> and Array<unknown>, because cliffy can not know with sub command was executed to provide the specific types. In this case use action handlers.