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682 lines
16 KiB
Markdown
682 lines
16 KiB
Markdown
yargs
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========
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Yargs be a node.js library fer hearties tryin' ter parse optstrings.
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With yargs, ye be havin' a map that leads straight to yer treasure! Treasure of course, being a simple option hash.
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[](https://travis-ci.org/chevex/yargs)
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[](https://gemnasium.com/chevex/yargs)
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[](http://badge.fury.io/js/yargs)
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> ~~NOTE: Yargs is a fork of [optimist](https://github.com/substack/node-optimist) by [substack (James Halliday)](https://github.com/substack). It is obvious that substack is stretched pretty thin maintaining over 300 modules on npm at the time of this writing. So rather than complain in the project issue tracker I thought I'd just pick up the torch and maintain a proper fork. Currently the project is totally backward compatible with optimist but this may change in the future (if it does I will update this notice to inform you of this). For now though, enjoy optimist with about 5 months worth of fixes and updates rolled in, most of them pulled from optimist's own [stale pull requests](https://github.com/substack/node-optimist/pulls).~~
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> UPDATE: Yargs is now the official successor to optimist. Please feel free to submit issues and pull requests. While I personally don't have the time to pore over all the issues and fix all of them on a regular basis, I'm more than happy to look over pull requests, test them, and merge them in. If you'd like to contribute and don't know where to start, have a look at [the issue list](https://github.com/chevex/yargs/issues) :)
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examples
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========
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With yargs, the options be just a hash!
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-------------------------------------------------------------------
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xup.js:
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````javascript
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#!/usr/bin/env node
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var argv = require('yargs').argv;
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if (argv.rif - 5 * argv.xup > 7.138) {
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console.log('Plunder more riffiwobbles!');
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}
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else {
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console.log('Drop the xupptumblers!');
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}
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````
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***
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$ ./xup.js --rif=55 --xup=9.52
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Plunder more riffiwobbles!
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$ ./xup.js --rif 12 --xup 8.1
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Drop the xupptumblers!
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But don't walk the plank just yet! There be more! You can do short options:
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-------------------------------------------------
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short.js:
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````javascript
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#!/usr/bin/env node
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var argv = require('yargs').argv;
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console.log('(%d,%d)', argv.x, argv.y);
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````
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***
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$ ./short.js -x 10 -y 21
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(10,21)
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And booleans, both long, short, and even grouped:
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----------------------------------
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bool.js:
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````javascript
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#!/usr/bin/env node
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var util = require('util');
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var argv = require('yargs').argv;
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if (argv.s) {
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util.print(argv.fr ? 'Le perroquet dit: ' : 'The parrot says: ');
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}
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console.log(
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(argv.fr ? 'couac' : 'squawk') + (argv.p ? '!' : '')
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);
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````
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***
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$ ./bool.js -s
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The parrot says: squawk
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$ ./bool.js -sp
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The parrot says: squawk!
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$ ./bool.js -sp --fr
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Le perroquet dit: couac!
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And non-hyphenated options too! Just use `argv._`!
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-------------------------------------------------
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nonopt.js:
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````javascript
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#!/usr/bin/env node
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var argv = require('yargs').argv;
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console.log('(%d,%d)', argv.x, argv.y);
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console.log(argv._);
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````
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***
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$ ./nonopt.js -x 6.82 -y 3.35 rum
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(6.82,3.35)
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[ 'rum' ]
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$ ./nonopt.js "me hearties" -x 0.54 yo -y 1.12 ho
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(0.54,1.12)
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[ 'me hearties', 'yo', 'ho' ]
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Yargs even counts your booleans!
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----------------------------------------------------------------------
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count.js
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````javascript
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#!/usr/bin/env node
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var argv = require('yargs')
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.count('verbose')
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.alias('v', 'verbose')
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.argv;
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VERBOSE_LEVEL = argv.verbose;
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function WARN() { VERBOSE_LEVEL >= 0 && console.log.apply(console, arguments); }
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function INFO() { VERBOSE_LEVEL >= 1 && console.log.apply(console, arguments); }
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function DEBUG() { VERBOSE_LEVEL >= 2 && console.log.apply(console, arguments); }
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WARN("Showing only important stuff");
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INFO("Showing semi-mportant stuff too");
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DEBUG("Extra chatty mode");
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````
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***
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$ node count.js
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Showing only important stuff
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$ node count.js -v
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Showing only important stuff
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Showing semi-important stuff too
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$ node count.js -vv
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Showing only important stuff
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Showing semi-important stuff too
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Extra chatty mode
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$ node count.js -v --verbose
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Showing only important stuff
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Showing semi-important stuff too
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Extra chatty mode
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Tell users how to use yer options and make demands.
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-------------------------------------------------
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divide.js:
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````javascript
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#!/usr/bin/env node
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var argv = require('yargs')
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.usage('Usage: $0 -x [num] -y [num]')
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.demand(['x','y'])
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.argv;
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console.log(argv.x / argv.y);
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````
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***
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$ ./divide.js -x 55 -y 11
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5
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$ node ./divide.js -x 4.91 -z 2.51
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Usage: node ./divide.js -x [num] -y [num]
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Options:
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-x [required]
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-y [required]
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Missing required arguments: y
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After yer demands have been met, demand more! Ask for non-hypenated arguments!
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-----------------------------------------
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demand_count.js:
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````javascript
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#!/usr/bin/env node
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var argv = require('yargs')
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.demand(2)
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.argv;
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console.dir(argv)
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````
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***
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$ ./demand_count.js a
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Not enough arguments, expected 2, but only found 1
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$ ./demand_count.js a b
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{ _: [ 'a', 'b' ], '$0': 'node ./demand_count.js' }
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$ ./demand_count.js a b c
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{ _: [ 'a', 'b', 'c' ], '$0': 'node ./demand_count.js' }
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EVEN MORE SHIVER ME TIMBERS!
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------------------
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default_singles.js:
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````javascript
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#!/usr/bin/env node
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var argv = require('yargs')
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.default('x', 10)
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.default('y', 10)
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.argv
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;
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console.log(argv.x + argv.y);
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````
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***
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$ ./default_singles.js -x 5
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15
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default_hash.js:
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````javascript
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#!/usr/bin/env node
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var argv = require('yargs')
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.default({ x : 10, y : 10 })
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.argv
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;
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console.log(argv.x + argv.y);
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````
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***
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$ ./default_hash.js -y 7
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17
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And if you really want to get all descriptive about it...
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---------------------------------------------------------
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boolean_single.js
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````javascript
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#!/usr/bin/env node
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var argv = require('yargs')
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.boolean('v')
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.argv
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;
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console.dir(argv.v);
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console.dir(argv._);
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````
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***
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$ ./boolean_single.js -v "me hearties" yo ho
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true
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[ 'me hearties', 'yo', 'ho' ]
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boolean_double.js
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````javascript
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#!/usr/bin/env node
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var argv = require('yargs')
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.boolean(['x','y','z'])
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.argv
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;
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console.dir([ argv.x, argv.y, argv.z ]);
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console.dir(argv._);
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````
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***
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$ ./boolean_double.js -x -z one two three
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[ true, false, true ]
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[ 'one', 'two', 'three' ]
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Yargs is here to help you...
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---------------------------
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Ye can describe parameters fer help messages and set aliases. Yargs figures
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out how ter format a handy help string automatically.
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line_count.js
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````javascript
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#!/usr/bin/env node
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var argv = require('yargs')
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.usage('Count the lines in a file.\nUsage: $0')
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.example('$0 -f', 'count the lines in the given file')
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.demand('f')
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.alias('f', 'file')
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.describe('f', 'Load a file')
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.argv
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;
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var fs = require('fs');
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var s = fs.createReadStream(argv.file);
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var lines = 0;
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s.on('data', function (buf) {
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lines += buf.toString().match(/\n/g).length;
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});
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s.on('end', function () {
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console.log(lines);
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});
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````
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***
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$ node line_count.js
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Count the lines in a file.
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Usage: node ./line_count.js
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Examples:
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node ./line_count.js -f count the lines in the given file
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Options:
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-f, --file Load a file [required]
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Missing required arguments: f
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$ node line_count.js --file line_count.js
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20
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$ node line_count.js -f line_count.js
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20
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methods
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=======
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By itself,
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````javascript
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require('yargs').argv
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`````
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will use `process.argv` array to construct the `argv` object.
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You can pass in the `process.argv` yourself:
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````javascript
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require('yargs')([ '-x', '1', '-y', '2' ]).argv
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````
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or use .parse() to do the same thing:
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````javascript
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require('yargs').parse([ '-x', '1', '-y', '2' ])
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````
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The rest of these methods below come in just before the terminating `.argv`.
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.alias(key, alias)
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------------------
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Set key names as equivalent such that updates to a key will propagate to aliases
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and vice-versa.
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Optionally `.alias()` can take an object that maps keys to aliases.
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Each key of this object should be the canonical version of the option, and each
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value should be a string or an array of strings.
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.default(key, value)
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--------------------
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Set `argv[key]` to `value` if no option was specified on `process.argv`.
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Optionally `.default()` can take an object that maps keys to default values.
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.demand(key, [msg | boolean])
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-----------------------------
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.require(key, [msg | boolean])
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------------------------------
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.required(key, [msg | boolean])
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-------------------------------
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If `key` is a string, show the usage information and exit if `key` wasn't
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specified in `process.argv`.
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If `key` is a number, demand at least as many non-option arguments, which show
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up in `argv._`.
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If `key` is an Array, demand each element.
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If a `msg` string is given, it will be printed when the argument is missing,
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instead of the standard error message. This is especially helpful for the non-option arguments in `argv._`.
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If a `boolean` value is given, it controls whether the option is demanded;
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this is useful when using `.options()` to specify command line parameters.
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.requiresArg(key)
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-----------------
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Specifies either a single option key (string), or an array of options that
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must be followed by option values. If any option value is missing, show the
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usage information and exit.
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The default behaviour is to set the value of any key not followed by an
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option value to `true`.
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.describe(key, desc)
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--------------------
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Describe a `key` for the generated usage information.
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Optionally `.describe()` can take an object that maps keys to descriptions.
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.options(key, opt)
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------------------
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Instead of chaining together `.alias().demand().default()`, you can specify
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keys in `opt` for each of the chainable methods.
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For example:
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````javascript
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var argv = require('yargs')
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.options('f', {
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alias : 'file',
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default : '/etc/passwd',
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})
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.argv
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;
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````
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is the same as
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````javascript
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var argv = require('yargs')
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.alias('f', 'file')
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.default('f', '/etc/passwd')
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.argv
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;
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````
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Optionally `.options()` can take an object that maps keys to `opt` parameters.
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.usage(message, opts)
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---------------------
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Set a usage message to show which commands to use. Inside `message`, the string
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`$0` will get interpolated to the current script name or node command for the
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present script similar to how `$0` works in bash or perl.
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`opts` is optional and acts like calling `.options(opts)`.
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.example(cmd, desc)
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-------------------
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Give some example invocations of your program. Inside `cmd`, the string
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`$0` will get interpolated to the current script name or node command for the
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present script similar to how `$0` works in bash or perl.
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Examples will be printed out as part of the help message.
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.check(fn)
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----------
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Check that certain conditions are met in the provided arguments.
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`fn` is called with two arguments, the parsed `argv` hash and an array of options and their aliases.
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If `fn` throws or returns `false`, show the thrown error, usage information, and
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exit.
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.boolean(key)
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-------------
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Interpret `key` as a boolean. If a non-flag option follows `key` in
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`process.argv`, that string won't get set as the value of `key`.
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If `key` never shows up as a flag in `process.arguments`, `argv[key]` will be
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`false`.
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If `key` is an Array, interpret all the elements as booleans.
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.string(key)
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------------
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Tell the parser logic not to interpret `key` as a number or boolean.
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This can be useful if you need to preserve leading zeros in an input.
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If `key` is an Array, interpret all the elements as strings.
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.config(key)
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------------
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Tells the parser to interpret `key` as a path to a JSON config file. The file
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is loaded and parsed, and its properties are set as arguments.
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.wrap(columns)
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--------------
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Format usage output to wrap at `columns` many columns.
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.strict()
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---------
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Any command-line argument given that is not demanded, or does not have a
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corresponding description, will be reported as an error.
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.help([option, [description]])
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------------------------------
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Add an option (e.g., `--help`) that displays the usage string and exits the
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process. If present, the `description` parameter customises the description of
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the help option in the usage string.
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If invoked without parameters, `.help` returns the generated usage string.
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Example:
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```
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var yargs = require("yargs")
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.usage("$0 -operand1 number -operand2 number -operation [add|subtract]");
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console.log(yargs.help());
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```
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Later on, ```argv``` can be retrived with ```yargs.argv```
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.version(version, option, [description])
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----------------------------------------
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Add an option (e.g., `--version`) that displays the version number (given by the
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`version` parameter) and exits the process. If present, the `description`
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parameter customises the description of the version option in the usage string.
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.showHelpOnFail(enable, [message])
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----------------------------------
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By default, yargs outputs a usage string if any error is detected. Use the
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`.showHelpOnFail` method to customize this behaviour. if `enable` is `false`,
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the usage string is not output. If the `message` parameter is present, this
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message is output after the error message.
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line_count.js
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````javascript
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#!/usr/bin/env node
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var argv = require('yargs')
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.usage('Count the lines in a file.\nUsage: $0')
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.demand('f')
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.alias('f', 'file')
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.describe('f', 'Load a file')
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.showHelpOnFail(false, "Specify --help for available options")
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.argv;
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// etc.
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````
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***
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$ node line_count.js --file
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Missing argument value: f
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Specify --help for available options
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.showHelp(fn=console.error)
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---------------------------
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Print the usage data using `fn` for printing.
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Example:
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```
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var yargs = require("yargs")
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.usage("$0 -operand1 number -operand2 number -operation [add|subtract]");
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yargs.showHelp();
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```
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Later on, ```argv``` can be retrived with ```yargs.argv```
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.parse(args)
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------------
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Parse `args` instead of `process.argv`. Returns the `argv` object.
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.argv
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-----
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Get the arguments as a plain old object.
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Arguments without a corresponding flag show up in the `argv._` array.
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The script name or node command is available at `argv.$0` similarly to how `$0`
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works in bash or perl.
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parsing tricks
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==============
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stop parsing
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------------
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Use `--` to stop parsing flags and stuff the remainder into `argv._`.
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$ node examples/reflect.js -a 1 -b 2 -- -c 3 -d 4
|
|
{ _: [ '-c', '3', '-d', '4' ],
|
|
'$0': 'node ./examples/reflect.js',
|
|
a: 1,
|
|
b: 2 }
|
|
|
|
negate fields
|
|
-------------
|
|
|
|
If you want to explicity set a field to false instead of just leaving it
|
|
undefined or to override a default you can do `--no-key`.
|
|
|
|
$ node examples/reflect.js -a --no-b
|
|
{ _: [],
|
|
'$0': 'node ./examples/reflect.js',
|
|
a: true,
|
|
b: false }
|
|
|
|
numbers
|
|
-------
|
|
|
|
Every argument that looks like a number (`!isNaN(Number(arg))`) is converted to
|
|
one. This way you can just `net.createConnection(argv.port)` and you can add
|
|
numbers out of `argv` with `+` without having that mean concatenation,
|
|
which is super frustrating.
|
|
|
|
duplicates
|
|
----------
|
|
|
|
If you specify a flag multiple times it will get turned into an array containing
|
|
all the values in order.
|
|
|
|
$ node examples/reflect.js -x 5 -x 8 -x 0
|
|
{ _: [],
|
|
'$0': 'node ./examples/reflect.js',
|
|
x: [ 5, 8, 0 ] }
|
|
|
|
dot notation
|
|
------------
|
|
|
|
When you use dots (`.`s) in argument names, an implicit object path is assumed.
|
|
This lets you organize arguments into nested objects.
|
|
|
|
$ node examples/reflect.js --foo.bar.baz=33 --foo.quux=5
|
|
{ _: [],
|
|
'$0': 'node ./examples/reflect.js',
|
|
foo: { bar: { baz: 33 }, quux: 5 } }
|
|
|
|
short numbers
|
|
-------------
|
|
|
|
Short numeric `head -n5` style argument work too:
|
|
|
|
$ node reflect.js -n123 -m456
|
|
{ '3': true,
|
|
'6': true,
|
|
_: [],
|
|
'$0': 'node ./reflect.js',
|
|
n: 123,
|
|
m: 456 }
|
|
|
|
installation
|
|
============
|
|
|
|
With [npm](http://github.com/isaacs/npm), just do:
|
|
|
|
npm install yargs
|
|
|
|
or clone this project on github:
|
|
|
|
git clone http://github.com/chevex/yargs.git
|
|
|
|
To run the tests with [expresso](http://github.com/visionmedia/expresso),
|
|
just do:
|
|
|
|
expresso
|
|
|
|
inspired By
|
|
===========
|
|
|
|
This module is loosely inspired by Perl's
|
|
[Getopt::Casual](http://search.cpan.org/~photo/Getopt-Casual-0.13.1/Casual.pm).
|