mysqladmin status command

mysqladmin status

MySQL show status command to see open database connections example

mysql> show status like 'Conn%';

See the number of currently open connections

mysql> show status like '%onn%';

Use show processlist sql command to see the number of open connections

mysql> show processlist;

Use netstat or ss command to list open database connections

netstat -nat | grep :3306

Source: https://www.cyberciti.biz/faq/howto-show-mysql-open-database-connections-on-linux-unix/