sync.js

#!/usr/bin/env node

var
	exec = require('child_process').exec,
	path = require('path');

var
	is_reverse = ~ process.argv.indexOf('reverse');
	sync = require('./sync.list'),
	LEFT_PREFIX = '~',
	RIGHT_PREFIX = '~/Dropbox';

function compare (list)
{
	var
		pair = head(list),
		left = path.join(LEFT_PREFIX, pair[0]),
		right = path.join(RIGHT_PREFIX, pair[1]);

	if (is_reverse)
	{
		var swap = left;
		left = right;
		right = swap;
	}

	console.log('Comparing:');
	console.log('*', left);
	console.log('*', right);

	differs(left, right, function (r)
	{
		console.log('>', r ? 'differs' : 'identical');
		if (r)
		{
			var command = 'meld '+ left +' '+ right;
			exec(command, proceed);
		}
		else proceed();

		function proceed ()
		{
			if (list.length)
			{
				compare(list);
			}
		}
	});
};

function head (list)
{
	return list.shift();
};

function differs (f1, f2, callback)
{
	var command = 'diff -q '+ f1 +' '+ f2;
	exec(command, function (ret)
	{
		callback(ret != null);
	});
}

compare(sync);