Linux is an Unix based Operating System,in which we can change the password easily than OS X.
For changing the password, Restart your computer & press the ESC key when GRUB appears. Scrolldown & highlight ‘Recovery Mode’ & then press ‘B’ key; It will make you to enter into ‘Single User Mode’. Now you are at the prompt, & logged in as ‘root’ byDefault. Type ‘passwd’ & choose a new password. It will change the root password to whatever you enter. If you are interested in only gaining access for a single account @ system, then type ‘passwd username’ replacing ‘username’ with the log-in name for the account you would like to alter the password. Now you got access................