When you run Magento 2 CLI command "bin/magento ..." and get the error:
Allowed memory size of xxxx bytes exhausted (tried to allocate xxx bytes)
You can easily fix it using this command instead of bin/magento:
php -dmemory_limit=-1 bin/magento ....
Examples:
php -dmemory_limit=-1 bin/magento setup:upgrade
php -dmemory_limit=-1 bin/magento setup:di:compile
This error is related to the memory limit configuration in PHP. Parameter -dmemory_limit=-1 allows to run PHP in the CLI without memory limits.
You can also change memory_limit configurations (php.ini file).
Both are correct. They are the same and you can use one you like more. As for me, I like to use -dmemory_limit without space.