在Linux系統上，查看MySQL的密碼位數可以通過以下步驟來完成。

$ sudo mysql -u root -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.28-0ubuntu0.18.04.4 (Ubuntu)
Copyright (c) 2000, 2020, Oracle and/or its affiliates.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql>SELECT LENGTH(User_Password) FROM mysql.user WHERE User = 'root';
+------------------------+
| LENGTH(User_Password)  |
+------------------------+
|                     41 |
+------------------------+
1 row in set (0.00 sec)

首先我們需要以root用戶身份登錄MySQL，然后執行“SELECT LENGTH(User_Password) FROM mysql.user WHERE User = 'root'”查詢語句，將會返回密碼的字符位數。

以上就是在Linux系統上查看MySQL密碼位數的方法。