Linux Change Password

How do I change my own password as well as the passwords of other users as required under Linux operating system without using GUI systems?

You can use the passwd command to change your password, and, as a system administrator, change the password of the root account, or another user in your Linux system. The syntax is as follows:

 
passwd
passwd {userName}
 

Task: Linux Change Your Own Password

Login using the ssh client or open a command-line terminal (select Applications > Accessories > Terminal), than type the following command:
$ passwd
First, the user is prompted for their current password. If the current password is correctly typed, a new password is requested. The new password must be entered twice to avoid typing errors. Running passwd command with no arguments will allow you to change your own password.

Task: Linux Change root's User Password

To change root's password, you must first login as root user or use sudo / su command to obtain root's credentials. To become the root user, enter:
$ su -l
OR
$ sudo -s
Next, to change root's password, enter:
# passwd

WARNING! You can change root's password only if you are logged in as the root user!

Task: Linux Change Another User's Password

To change the password of another user, login as root and type:
# passwd userNameHere
# passwd tom
# passwd jerry

Getting Help

Anytime you need assistance with Linux passwd command-line, turn to the man page first. It will give you detailed information, parameters and switches for passwd command. For example, man passwd opens the man page for the passwd command:
$ man passwd
$ man 5 passwd