mysql> use mysql;
mysql> update user set password=password("new-password") where user = "root";
mysql> flush privileges;

You may accomplish the same task with mysqladmin MySQL command.

$ mysqladmin -u root password 'new-password'

If you wish to change existing root password, you'll use the following command instead. When entered, you'll be prompted for current root password.

$ mysqladmin -u root -p password 'new-password'

NOTE: You do not have to run “flush privileges” MySQL command to reload the privileges when you use “mysqladmin” command.

If you wish to setup “root” or any user login without having to supply password on command-prompt, you may create .my.cnf file in your home directory. MySQL reads this file each time it opens the MySQL client. Create the ~/.my.cnf file. [Note: ~ represents your HOME directory path in Linux]

.my.cnf

[client]
user=root
password=root-password
host=127.0.0.1
 
[mysql]
database = database-name

Be sure to modify the permission of the file to limit access to yourself, so that other users on the system cannot view this file.

chmod 600 ~/.my.cnf