composer使用内存超出，使用php -d可以临时设置php.ini中变量。感觉挺有意思，到服务器上找了具体的参数和说明。
供大家参考
Usage: php [options] [-f] <file> [--] [args...]
php [options] -r <code> [--] [args...]
php [options] [-B <begin_code>] -R <code> [-E <end_code>] [--] [args...]
php [options] [-B <begin_code>] -F <file> [-E <end_code>] [--] [args...]
php [options] -S <addr>:<port> [-t docroot] [router]
php [options] -- [args...]
php [options] -a
-a Run interactively
-c <path>|<file> Look for php.ini file in this directory
-n No configuration (ini) files will be used
-d foo[=bar] Define INI entry foo with value 'bar'
-e Generate extended information for debugger/profiler
-f <file> Parse and execute <file>.
-h This help
-i PHP information
-l Syntax check only (lint)
-m Show compiled in modules
-r <code> Run PHP <code> without using script tags <?..?>
-B <begin_code> Run PHP <begin_code> before processing input lines
-R <code> Run PHP <code> for every input line
-F <file> Parse and execute <file> for every input line
-E <end_code> Run PHP <end_code> after processing all input lines
-H Hide any passed arguments from external tools.
-S <addr>:<port> Run with built-in web server.
-t <docroot> Specify document root <docroot> for built-in web server.
-s Output HTML syntax highlighted source.
-v Version number
-w Output source with stripped comments and whitespace.
-z <file> Load Zend extension <file>.
args... Arguments passed to script. Use -- args when first argument
starts with - or script is read from stdin
--ini Show configuration file names
--rf <name> Show information about function <name>.
--rc <name> Show information about class <name>.
--re <name> Show information about extension <name>.
--rz <name> Show information about Zend extension <name>.
--ri <name> Show configuration for extension <name>.