MySQL Change root Password

How do I change MySQL root password under Linux.

Setting up mysql password is one of the essential tasks. By default root user is MySQL admin account. Please note that the Linux / UNIX login root account for your operating system and MySQL root are different. They are separate and nothing to do with each other (indeed some admin removes root account and setup admin as mysql super user).
mysqladmin command to change root password

If you have never set a root password for MySQL, the server does not require a password at all for connecting as root. To setup root password for first time, use mysqladmin command at shell prompt as follows:

$ mysqladmin -u root password NEWPASSWORD

However, if you want to change (or update) a root password, then you need to use following command

$ mysqladmin -u root -p'oldpassword' password newpass

For example, If old password is abc, and set new password to mysql123, enter:

$ mysqladmin -u root -p'abc' password 'mysql123'