在Linux系統下，我們可以通過命令行查看當前MySQL數據庫的連接數。下面介紹兩種方法。

方法一：

$ mysql -u username -p
Enter password:
mysql>status;
--------------
mysql  Ver 14.14 Distrib 5.7.35, for Linux (x86_64) using  EditLine wrapper
Connection id:          12
Current database:
Current user:           username@localhost
SSL:                    Not in use
Current pager:          stdout
Using outfile:          ''
Using delimiter:        ;
Server version:         5.7.35-0ubuntu0.18.04.1 (Ubuntu)
Protocol version:       10
Connection:             localhost via UNIX socket
Server characterset:    utf8mb4
Db     characterset:    utf8mb4
Client characterset:    utf8mb4
Conn.  characterset:    utf8mb4
UNIX socket:            /var/run/mysqld/mysqld.sock
Uptime:                 42 min 6 sec
Threads: 1  Questions: 1186  Slow queries: 0  Opens: 115  Flush tables: 1  Open tables: 60  Queries per second avg: 0.468
--------------

上面的status命令可以查看當前連接數，如果是在客戶端機器上，則需要安裝MySQL客戶端。

方法二：

$ mysqladmin -u username -p status
Enter password:
Uptime: 2717  Threads: 9  Questions: 4406  Slow queries: 0  Opens: 50  Flush tables: 1  Open tables: 44  Queries per second avg: 1.621

這種方法不需要進入MySQL客戶端，直接在命令行下執行即可。