The complete solution for [node.js](http://nodejs.org) command-line interfaces, inspired by Ruby's [commander](https://github.com/commander-rb/commander).
Read this in other languages: English | [简体中文](./Readme_zh-CN.md)
- [Commander for enterprise](#commander-for-enterprise)
## Installation
```bash
npm install commander
```
## Declaring _program_ variable
Commander exports a global object which is convenient for quick programs.
This is used in the examples in this README for brevity.
```js
const { program } = require('commander');
program.version('0.0.1');
```
For larger programs which may use commander in multiple ways, including unit testing, it is better to create a local Command object to use.
```js
const { Command } = require('commander');
const program = new Command();
program.version('0.0.1');
```
## Options
Options are defined with the `.option()` method, also serving as documentation for the options. Each option can have a short flag (single character) and a long name, separated by a comma or space or vertical bar ('|').
The options can be accessed as properties on the Command object. Multi-word options such as "--template-engine" are camel-cased, becoming `program.templateEngine` etc. See also optional new behaviour to [avoid name clashes](#avoiding-option-name-clashes).
Multiple short flags may optionally be combined in a single argument following the dash: boolean flags, the last flag may take a value, and the value.
For example `-a -b -p 80` may be written as `-ab -p80` or even `-abp80`.
You can use `--` to indicate the end of the options, and any remaining arguments will be used without being interpreted.
This is particularly useful for passing options through to another
command, like: `do -- git --version`.
Options on the command line are not positional, and can be specified before or after other command arguments.
### Common option types, boolean and value
The two most used option types are a boolean flag, and an option which takes a value (declared using angle brackets). Both are `undefined` unless specified on command line.
```js
const { program } = require('commander');
program
.option('-d, --debug', 'output extra debugging')
.option('-s, --small', 'small pizza size')
.option('-p, --pizza-type <type>', 'flavour of pizza');
program.parse(process.argv);
if (program.debug) console.log(program.opts());
console.log('pizza details:');
if (program.small) console.log('- small pizza size');
if (program.pizzaType) console.log(`- ${program.pizzaType}`);
if (program.float !== undefined) console.log(`float: ${program.float}`);
if (program.integer !== undefined) console.log(`integer: ${program.integer}`);
if (program.verbose > 0) console.log(`verbosity: ${program.verbose}`);
if (program.collect.length > 0) console.log(program.collect);
if (program.list !== undefined) console.log(program.list);
```
```bash
$ custom -f 1e2
float: 100
$ custom --integer 2
integer: 2
$ custom -v -v -v
verbose: 3
$ custom -c a -c b -c c
[ 'a', 'b', 'c' ]
$ custom --list x,y,z
[ 'x', 'y', 'z' ]
```
### Required option
You may specify a required (mandatory) option using `.requiredOption`. The option must have a value after parsing, usually specified on the command line, or perhaps from a default value (say from environment). The method is otherwise the same as `.option` in format, taking flags and description, and optional default value or custom processing.
```js
const { program } = require('commander');
program
.requiredOption('-c, --cheese <type>', 'pizza must have cheese');
program.parse(process.argv);
```
```bash
$ pizza
error: required option '-c, --cheese <type>' not specified
```
### Version option
The optional `version` method adds handling for displaying the command version. The default option flags are `-V` and `--version`, and when present the command prints the version number and exits.
```js
program.version('0.0.1');
```
```bash
$ ./examples/pizza -V
0.0.1
```
You may change the flags and description by passing additional parameters to the `version` method, using
the same syntax for flags as the `option` method. The version flags can be named anything, but a long name is required.
```js
program.version('0.0.1', '-v, --vers', 'output the current version');
```
## Commands
You can specify (sub)commands using `.command()` or `.addCommand()`. There are two ways these can be implemented: using an action handler attached to the command, or as a stand-alone executable file (described in more detail later). The subcommands may be nested ([example](./examples/nestedCommands.js)).
In the first parameter to `.command()` you specify the command name and any command arguments. The arguments may be `<required>` or `[optional]`, and the last argument may also be `variadic...`.
You can use `.addCommand()` to add an already configured subcommand to the program.
For example:
```js
// Command implemented using action handler (description is supplied separately to `.command`)
// Returns new command for configuring.
program
.command('clone <source> [destination]')
.description('clone a repository into a newly created directory')
.action((source, destination) => {
console.log('clone command called');
});
// Command implemented using stand-alone executable file (description is second parameter to `.command`)
// Returns `this` for adding more commands.
program
.command('start <service>', 'start named service')
.command('stop [service]', 'stop named service, or all if no name supplied');
// Command prepared separately.
// Returns `this` for adding more commands.
program
.addCommand(build.makeBuildCommand());
```
Configuration options can be passed with the call to `.command()` and `.addCommand()`. Specifying `true` for `opts.hidden` will remove the command from the generated help output. Specifying `true` for `opts.isDefault` will run the subcommand if no other subcommand is specified ([example](./examples/defaultCommand.js)).
### Specify the argument syntax
You use `.arguments` to specify the arguments for the top-level command, and for subcommands they are usually included in the `.command` call. Angled brackets (e.g. `<required>`) indicate required input. Square brackets (e.g. `[optional]`) indicate optional input.
```js
const { program } = require('commander');
program
.version('0.1.0')
.arguments('<cmd> [env]')
.action(function (cmd, env) {
cmdValue = cmd;
envValue = env;
});
program.parse(process.argv);
if (typeof cmdValue === 'undefined') {
console.error('no command given!');
process.exit(1);
}
console.log('command:', cmdValue);
console.log('environment:', envValue || "no environment given");
```
The last argument of a command can be variadic, and only the last argument. To make an argument variadic you
append `...` to the argument name. For example:
```js
const { program } = require('commander');
program
.version('0.1.0')
.command('rmdir <dir> [otherDirs...]')
.action(function (dir, otherDirs) {
console.log('rmdir %s', dir);
if (otherDirs) {
otherDirs.forEach(function (oDir) {
console.log('rmdir %s', oDir);
});
}
});
program.parse(process.argv);
```
The variadic argument is passed to the action handler as an array.
### Action handler (sub)commands
You can add options to a command that uses an action handler.
The action handler gets passed a parameter for each argument you declared, and one additional argument which is the
command object itself. This command argument has the values for the command-specific options added as properties.
You may supply an `async` action handler, in which case you call `.parseAsync` rather than `.parse`.
```js
async function run() { /* code goes here */ }
async function main() {
program
.command('run')
.action(run);
await program.parseAsync(process.argv);
}
```
A command's options on the command line are validated when the command is used. Any unknown options will be reported as an error.
### Stand-alone executable (sub)commands
When `.command()` is invoked with a description argument, this tells Commander that you're going to use stand-alone executables for subcommands.
Commander will search the executables in the directory of the entry script (like `./examples/pm`) with the name `program-subcommand`, like `pm-install`, `pm-search`.
You can specify a custom name with the `executableFile` configuration option.
You handle the options for an executable (sub)command in the executable, and don't declare them at the top-level.
```js
// file: ./examples/pm
const { program } = require('commander');
program
.version('0.1.0')
.command('install [name]', 'install one or more packages')
.command('search [query]', 'search with optional query')
The original and default behaviour is that the option values are stored
as properties on the program, and the action handler is passed a
command object with the options values stored as properties.
This is very convenient to code, but the downside is possible clashes with
existing properties of Command.
There are two new routines to change the behaviour, and the default behaviour may change in the future:
-`storeOptionsAsProperties`: whether to store option values as properties on command object, or store separately (specify false) and access using `.opts()`
-`passCommandToAction`: whether to pass command to action handler,
The Commander package includes its TypeScript Definition file.
If you use `ts-node` and stand-alone executable subcommands written as `.ts` files, you need to call your program through node to get the subcommands called correctly. e.g.
```bash
node -r ts-node/register pm.ts
```
### createCommand()
This factory function creates a new command. It is exported and may be used instead of using `new`, like:
```js
const { createCommand } = require('commander');
const program = createCommand();
```
`createCommand` is also a method of the Command object, and creates a new command rather than a subcommand. This gets used internally
when creating subcommands using `.command()`, and you may override it to
customise the new subcommand (examples using [subclass](./examples/custom-command-class.js) and [function](./examples/custom-command-function.js)).
### Node options such as `--harmony`
You can enable `--harmony` option in two ways:
- Use `#! /usr/bin/env node --harmony` in the subcommands scripts. (Note Windows does not support this pattern.)
- Use the `--harmony` option when call the command, like `node --harmony examples/pm publish`. The `--harmony` option will be preserved when spawning subcommand process.
### Debugging stand-alone executable subcommands
An executable subcommand is launched as a separate child process.
If you are using the node inspector for [debugging](https://nodejs.org/en/docs/guides/debugging-getting-started/) executable subcommands using `node --inspect` et al,
the inspector port is incremented by 1 for the spawned subcommand.
If you are using VSCode to debug executable subcommands you need to set the `"autoAttachChildProcesses": true` flag in your launch.json configuration.
### Override exit handling
By default Commander calls `process.exit` when it detects errors, or after displaying the help or version. You can override
this behaviour and optionally supply a callback. The default override throws a `CommanderError`.
The override callback is passed a `CommanderError` with properties `exitCode` number, `code` string, and `message`. The default override behaviour is to throw the error, except for async handling of executable subcommand completion which carries on. The normal display of error messages or version or help
is not affected by the override which is called after the display.
``` js
program.exitOverride();
try {
program.parse(process.argv);
} catch (err) {
// custom processing...
}
```
## Examples
```js
const { program } = require('commander');
program
.version('0.1.0')
.option('-C, --chdir <path>', 'change the working directory')
.option('-c, --config <path>', 'set config path. defaults to ./deploy.conf')
.option('-T, --no-tests', 'ignore test hook');
program
.command('setup [env]')
.description('run setup commands for all envs')
.option("-s, --setup_mode [mode]", "Which setup mode to use")
.action(function(env, options){
const mode = options.setup_mode || "normal";
env = env || 'all';
console.log('setup for %s env(s) with %s mode', env, mode);
});
program
.command('exec <cmd>')
.alias('ex')
.description('execute the given remote cmd')
.option("-e, --exec_mode <mode>", "Which exec mode to use")
.action(function(cmd, options){
console.log('exec "%s" using %s mode', cmd, options.exec_mode);
}).on('--help', function() {
console.log('');
console.log('Examples:');
console.log('');
console.log(' $ deploy exec sequential');
console.log(' $ deploy exec async');
});
program.parse(process.argv);
```
More Demos can be found in the [examples](https://github.com/tj/commander.js/tree/master/examples) directory.
Commander 5.x is fully supported on Long Term Support versions of Node, and is likely to work with Node 6 but not tested.
(For versions of Node below Node 6, use Commander 3.x or 2.x.)
The main forum for free and community support is the project [Issues](https://github.com/tj/commander.js/issues) on GitHub.
### Commander for enterprise
Available as part of the Tidelift Subscription
The maintainers of Commander and thousands of other packages are working with Tidelift to deliver commercial support and maintenance for the open source dependencies you use to build your applications. Save time, reduce risk, and improve code health, while paying the maintainers of the exact dependencies you use. [Learn more.](https://tidelift.com/subscription/pkg/npm-commander?utm_source=npm-commander&utm_medium=referral&utm_campaign=enterprise&utm_term=repo)
