Force users to change their passwords upon first login

Taken from Redhat Magazine: Tips and tricks: How do I force users to change their passwords upon first login?

1. Firstly, lock the account to prevent the user from using the login until the change has been made:
   
   # usermod -L
   
2. Change the password expiration date to 0 to ensure the user changes the password during the next login:
   
   # chage -d 0
   
   
3. To unlock the account after the change do the following:
   
   # usermod -U