gistfile1.js

/**
 * Usage:
 *   phantomjs screenshot.js http://google.de /pi/a.png
 */
var page = require('webpage').create(),
    system = require('system');

page.viewportSize = { width: 1280, height: 800 };

if (system.args.length === 1) {
    console.log('Usage: screenshot.js <some URL> <Image>');
    phantom.exit();
}

var address = system.args[1];
var image = system.args[2];

page.open(address, function (status) {
    if (status !== 'success') {
        console.log('FAIL to load the address');
    } else {
        page.render(image);
    }
    phantom.exit();
});