Memory limit errors

If composer shows memory errors on some commands:

PHP Fatal error:  Allowed memory size of XXXXXX bytes exhausted <...>

The memory_limit ini value should be increased.

Get current value:

php -r "echo ini_get('memory_limit').PHP_EOL;"

Increase limit with php.ini for a CLI SAPI (ex. /etc/php5/cli/php.ini for Debian-like systems):

; Use -1 for unlimited or define explicit value like 512M
memory_limit = -1

Or with command line arguments:

php -d memory_limit=-1 composer.phar <...>