php – laravel4 composer安装得到proc_open不可用的错误

现在我试图用composer来安装我的PHP包,但是我收到了这个错误信息：
$composer安装

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.

编辑：

在启用proc_open函数后,我收到此错误,并将我的PHP memory_limit设置为384M：

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,Array)
#2 phar:///usr/local/bin/composer/vendor/symfony/console/Symfony/Component/Console/Application.PHP(832): Symfony\Component\Console\Application->getSttyColumns()
#3 phar:///usr/local/bin/composer/vendor/symfony/console/Symfony/Component/Console/Application.PHP(797): Symfony\Component\Console\Application->getTerminalDimensions()
#4 phar:///usr/local/bin/composer/vendor/symfony/console/Symfony/Component/Console/Application.PHP(731): Symfony\Component\Console\Application->getTerminalWidth()
#5 phar:///usr/local/bin/com in phar:///usr/local/bin/composer/vendor/symfony/console/Symfony/Component/Console/Application.PHP on line 990

编辑您的PHP.ini文件并搜索该行

disable_functions = pcntl_alarm,pcntl_fork,pcntl_waitpid,pcntl_wait...

它应该在那里被禁用,你必须启用它.这是一个安全预防措施.