A normal Linux user can only change the password for his/her own account, but the super-user (root) may change the password for any user in the linux operating system.
For changing the password, the admin/super user is first prompted for his/her old password, if it exists. Then this password is encrypted and compared against the stored password.
The super-user has the ability to bypass the old password requirement so that forgotten passwords can be changed by a privileged user.
passwd is the command to change your own password in Linux Terminal:
$ passwd Changing password for steve (current) UNIX password: Enter new UNIX password: Retype new UNIX password: passwd: password updated successfully
If you want to change the password for some other user, you can do that as well with the same command prefixed with “sudo”.
# sudo passwd steve