This was asked and solved previously, but for Craft 2, see Error Connecting To (MAMP Pro) Database in Console Command. Unable to make it work here.
In short, running console commands like ./craft abc in Craft 3 configured using MAMP gives
Craft isn’t installed yet!
Exception 'craft\errors\DbConnectException' with message 'Craft CMS can’t connect to the database with the credentials in config/db.php.'
in /Users/stian/dev/site.no/vendor/craftcms/cms/src/db/Connection.php:179
Stack trace:
#0 /Users/stian/dev/site.no/vendor/yiisoft/yii2/db/Connection.php(996): craft\db\Connection->open()
#1 /Users/stian/dev/site.no/vendor/yiisoft/yii2/db/Connection.php(983): yii\db\Connection->getMasterPdo()
#2 /Users/stian/dev/site.no/vendor/yiisoft/yii2/db/mysql/QueryBuilder.php(380): yii\db\Connection->getSlavePdo()
#3 /Users/stian/dev/site.no/vendor/yiisoft/yii2/db/mysql/QueryBuilder.php(399): yii\db\mysql\QueryBuilder->supportsFractionalSeconds()
#4 /Users/stian/dev/site.no/vendor/yiisoft/yii2/db/mysql/QueryBuilder.php(57): yii\db\mysql\QueryBuilder->defaultTimeTypeMap()
#5 /Users/stian/dev/site.no/vendor/craftcms/cms/src/db/mysql/QueryBuilder.php(27): yii\db\mysql\QueryBuilder->init()
#6 /Users/stian/dev/site.no/vendor/yiisoft/yii2/base/BaseObject.php(109): craft\db\mysql\QueryBuilder->init()
#7 /Users/stian/dev/site.no/vendor/yiisoft/yii2/db/QueryBuilder.php(116): yii\base\BaseObject->__construct(Array)
#8 /Users/stian/dev/site.no/vendor/craftcms/cms/src/db/mysql/Schema.php(71): yii\db\QueryBuilder->__construct(Object(craft\db\Connection), Array)
#9 /Users/stian/dev/site.no/vendor/yiisoft/yii2/db/Schema.php(249): craft\db\mysql\Schema->createQueryBuilder()
#10 /Users/stian/dev/site.no/vendor/yiisoft/yii2/db/Connection.php(836): yii\db\Schema->getQueryBuilder()
#11 /Users/stian/dev/site.no/vendor/yiisoft/yii2/db/Command.php(580): yii\db\Connection->getQueryBuilder()
#12 /Users/stian/dev/site.no/vendor/craftcms/cms/src/db/Command.php(142): yii\db\Command->update('{{%queue}}', Array, '[[timeUpdated]]...', Array)
#13 /Users/stian/dev/site.no/vendor/craftcms/cms/src/queue/Queue.php(507): craft\db\Command->update('{{%queue}}', Array, '[[timeUpdated]]...', Array, false)
#14 /Users/stian/dev/site.no/vendor/craftcms/cms/src/queue/Queue.php(449): craft\queue\Queue->_moveExpired()
#15 /Users/stian/dev/site.no/vendor/craftcms/cms/src/queue/Queue.php(95): craft\queue\Queue->reserve()
#16 /Users/stian/dev/site.no/vendor/craftcms/cms/src/queue/Command.php(82): craft\queue\Queue->run()
#17 [internal function]: craft\queue\Command->actionRun()
#18 /Users/stian/dev/site.no/vendor/yiisoft/yii2/base/InlineAction.php(57): call_user_func_array(Array, Array)
#19 /Users/stian/dev/site.no/vendor/yiisoft/yii2/base/Controller.php(157): yii\base\InlineAction->runWithParams(Array)
#20 /Users/stian/dev/site.no/vendor/yiisoft/yii2/console/Controller.php(148): yii\base\Controller->runAction('run', Array)
#21 /Users/stian/dev/site.no/vendor/yiisoft/yii2/base/Module.php(528): yii\console\Controller->runAction('run', Array)
#22 /Users/stian/dev/site.no/vendor/yiisoft/yii2/console/Application.php(180): yii\base\Module->runAction('queue/run', Array)
#23 /Users/stian/dev/site.no/vendor/craftcms/cms/src/console/Application.php(93): yii\console\Application->runAction('queue/run', Array)
#24 /Users/stian/dev/site.no/vendor/yiisoft/yii2/console/Application.php(147): craft\console\Application->runAction('queue/run', Array)
#25 /Users/stian/dev/site.no/vendor/yiisoft/yii2/base/Application.php(386): yii\console\Application->handleRequest(Object(craft\console\Request))
#26 /Users/stian/dev/site.no/craft(22): yii\base\Application->run()
#27 {main}
Ideas?
