Linux Password Tools

To change any particular field for a given user,you should use the user management tools provided,such as the passwd command,adduser,usermod,userdel,and change.the passwd command lets you change the password only,other tools not only make entries in the /etc/passwd file,but also creat the home directory for the user and install initialization files in the user's home directory.

These tools also let you control user's access to their accounts.you can set expiration dates for users or lock them out of their accounts.users locked out of thir accounts will have their password in the /etc/shadow file prefixed by the invalid string.unlocking the account removes this prefix.