Often, we install MySQL Server in Ubuntu or Linux machines and then we tend to forget how to login to MySQL shell.
This may happen if we rarely login to MySQL Server since now a days most of the database table field additions and modifications can be handled by the Web app backend itself.
If you wanna show MySQL command line in Ubuntu or Linux, use the following command:
mysql -u <username> -p
Here -u stands for username and -p stands for password
You are required to replace <username> with your actual username for mysql. If you are trying to login as ROOT user. then you can use the command in the following way:
mysql -u root -p
Next you will be prompted with the password for root user. Once you enter the password. MySQL shell will appear where you can enter the MySQL query commands as usual.