Change a user’s password

# passwd username

Force password change at next login

# passwd -e username

Lock a user’s password

# passwd -l username

NOTE: this option does not disable a user, it only prevents the user to login using password as an authentication token, but it can still access using other means (for example, using ssh keys)

Unlock a user’s password

# passwd -u username

Show user password expiration

#  chage -l username
Minimum: 0
Maximum: 99999
Warning: 7
Inactive: -1
Last Change: May 10, 2011
Password Expires: Never
Password Inactive: Never
Account Expires: Never