Laravel 4 - Error while running `composer install` - php

Question

The problem:
I have installed Composer and followed the Quick start guide in the Laravel 4 documentation.
I get the following error when I run composer install or composer update:
Script php artisan optimize handling the post-install-cmd event
returned with an error...
I tried to run the following composer command:
composer create-project laravel/laravel myproject --prefer-dist
Or use their laravel.phar:
laravel new myproject
Or get the zip version from git: https://github.com/laravel/laravel?source=c
And I still fail to update via composer.
Additional information:
My PHP version on my Mac is:
PHP 5.4.17 (cli) (built: Aug 25 2013 02:03:38)
Copyright (c) 1997-2013 The PHP Group
Zend Engine v2.4.0,
Copyright (c) 1998-2013 Zend Technologies
PHP version on MAMP: 5.4.10
I found some solutions on Google / Stack Overflow but those did not work well in my case.

Answer 1

It says:
MCrypt PHP extension required
So it looks like you're missing the Mcrypt extension, which is required by Laravel (actually, I think it's used only by the Authentication class for password handling, not for the rest of the components of the framework).
I haven't got a Mac, but the command to install it should be something like this, using Homebrew
brew tap josegonzalez/php
brew install mcrypt php54-mcrypt
These links might help you:
http://www.jorble.com/2013/04/install-php-mcrypt-in-macosx/
http://coolestguidesontheplanet.com/install-mcrypt-php-mac-osx-10-9-mavericks-development-server/

Answer 2

Having the setting xdebug.scream = 1 in the configuration was the cause of the problem for me. I fixed it by doing the following:
Find XDebug configuration file.
$ sudo find / -name xdebug.ini
Edit file using any text editor.
$ sudo vi /your_path/xdebug.ini
Set xdebug.scream = 0
Reload the server (Apache/Nginx/whatever).
$ sudo service nginx reload

Answer 3

You might have Mcrypt installed already on your computer, if you are using MAMP or any other application. So, you don't need to install Mcrypt again. Add the following code to a php file and place it in your htdocs directory. See the info about the PHP you are running. You can see whether Mcrypt is already installed or not.
<?php
phpinfo();
If it shows Mcript, then do the following:
Check which PHP version you are using. You can see different directories for different PHP versions in this directory: /Applications/MAMP/bin/php/.
Move to the user's home directory. Use this command on terminal: cd ~.
Edit (or create a new one if not exists) .bash_profile file.
Add the following line:
where php5.5.10 is the directory of the PHP version you are using.
export PATH=/Applications/MAMP/bin/php/php5.5.10/bin:$PATH
Now restart your computer. And you can use php artisan command of Laravel.
Source of information: Laravel requires the Mcrypt PHP extension