title: laravel4 composer install got proc_open not available error
body: <p>Now I am trying to use composer to install my php package but I got this error message:
  $ composer install</p>
  
  <pre><code>Loading composer repositories with package information
  Installing dependencies (including require-dev)
    - Installing filp/whoops (1.0.7)
      Downloading: 100%          
  
  [Symfony\Component\Process\Exception\RuntimeException]                                   
  The Process class relies on proc_open, which is not available on your PHP installation. 
  </code></pre>
  
  <p>edit :</p>
  
  <p>after enable the proc_open function I got this error and also set my php memory_limit to 384M :</p>
  
  <pre><code>Fatal error: Uncaught exception 'ErrorException' with message 'proc_open(): fork failed - Cannot allocate memory' in phar:///usr/local/bin/composer/vendor/symfony/console/Symfony/Component/Console/Application.php:990
  Stack trace:
  #0 [internal function]: Composer\Util\ErrorHandler::handle(2, 'proc_open(): fo...', 'phar:///usr/loc...', 990, Array)
  #1 phar:///usr/local/bin/composer/vendor/symfony/console/Symfony/Component/Console/Application.php(990): proc_open('stty -a | grep ...', Array, NULL, NULL, NULL, Array)
  #2 phar:///usr/local/bin/composer/vendor/symfony/console/Symfony/Component/Console/Application.php(832): Symfony\Component\Console\Application-&gt;getSttyColumns()
  #3 phar:///usr/local/bin/composer/vendor/symfony/console/Symfony/Component/Console/Application.php(797): Symfony\Component\Console\Application-&gt;getTerminalDimensions()
  #4 phar:///usr/local/bin/composer/vendor/symfony/console/Symfony/Component/Console/Application.php(731): Symfony\Component\Console\Application-&gt;getTerminalWidth()
  #5 phar:///usr/local/bin/com in phar:///usr/local/bin/composer/vendor/symfony/console/Symfony/Component/Console/Application.php on line 990
  </code></pre>