I've found two libraries to sends whatsapps from Linux (and Windows, too):

• The first one is yowsup, in python
• The second one is WhatsAPI

I've found that the yowsup library works very well in the process of registering a telephone number and getting the necessary password. The problem of this library now is that it's too complicated to send a single message (I've tried it hard, I promise).

On the other hand WhatsAPI is simple to use, but –as far as I know–, the registration does not work.

So, I decided to mix the best of two worlds and get a process more or less simple to send a simple message.

Download the code:

git clone https://github.com/tgalal/yowsup.git

Start the registration by invoking:

yowsup-cli registration --requestcode sms --phone 49XXXXXXXX

Then, an sms will be sent to the phone in question. After this, confirm the registration by invoking:

yowsup-cli registration --register 123456 --phone 49XXXXXXXX

After this, you will get a phone number and a password. With this, you can use WhatsAPI to send your messages.

Download the source code of WhatsAPI:

git clone https://github.com/venomous0x/WhatsAPI.git

I've created a simple php program that just sends a message and exits:

<?php
set_time_limit(10);
require_once '../src/whatsprot.class.php';
//Change to your time zone
date_default_timezone_set('Europe/Madrid');
 
///////////////////////CONFIGURATION///////////////////////
//////////////////////////////////////////////////////////
$username = "49XXXXXXXXX"; // Telephone number including the country code
$password = "PUT THE PASSWORD HERE"; // A server generated Password
$identity = ""; // Obtained during registration with this API or using MissVeno
$nickname = ""; // This is the username (or nickname) d
$target = $argv[1]; // Destination telephone number including the country code 
$debug = false; // Set this to true, to see debug mode.
///////////////////////////////////////////////////////////
 
$w = new WhatsProt($username, $identity, $nickname, $debug);
$w->connect();
 
// Now loginWithPassword function sends Nickname and (Available) Presence
$w->loginWithPassword($password);
 
$w->sendMessage($target, argv[2]);
 
?>

And you can call by the command line:

$ php5 49DESTINATIONPHONE "this is a test message"

and that's it: sending whatsapp from a computer, direct and simple.