How to grep for Wordpress DB_NAME, DB_USER, DB_PASSWORD and DB_HOST in wp-config.php

This grep statement filters out the DB_NAME, DB_USER, DB_PASSWORD and DB_HOST contents from a wp-config.php:

grep -oP "define\(['\"]DB_NAME['\"],\s*['\"]\K[^'\"]+(?=[\'\"]\s*\)\s*;)" wp-config.php

For example, from the wp-config.php line

define('DB_NAME', 'techoverflow');

it will extract techoverflow.

Here are the statements for DB_NAME, DB_USER, DB_PASSWORD and DB_HOST:

DB_NAME=$(grep -oP "define\(['\"]DB_NAME['\"],\s*['\"]\K[^'\"]+(?=[\'\"]\s*\)\s*;)" wp-config.php)
DB_USER=$(grep -oP "define\(['\"]DB_USER['\"],\s*['\"]\K[^'\"]+(?=[\'\"]\s*\)\s*;)" wp-config.php)
DB_PASSWORD=$(grep -oP "define\(['\"]DB_PASSWORD['\"],\s*['\"]\K[^'\"]+(?=[\'\"]\s*\)\s*;)" wp-config.php)
DB_HOST=$(grep -oP "define\(['\"]DB_HOST['\"],\s*['\"]\K[^'\"]+(?=[\'\"]\s*\)\s*;)" wp-config.php)

You can use this, for example, in automatic backup scripts without manually copying the password to the backup script