How to become `root` in Linux?

[dmitrii_fediuk]

See also:

• How to fix «Please login as the user “ubuntu” rather than the user “root”»?
• How to prevent Ubuntu / Debian from asking for the current user’s password on sudo
• How to enable the root SSH login in Debian / Ubuntu (if it is disabled)?
• My sshd_config for Ubuntu in Amazon EC2

[dmitrii_fediuk]

Step 1

sudo su

Step 2

How do I register my SSH public key for `root' in Linux from the command line?

Step 3

How to enable the root SSH login in Debian / Ubuntu (if it is disabled)?