# Password aging controls:
#
# PASS_MAX_DAYS Maximum number of days a password may be used.
# PASS_MIN_DAYS Minimum number of days allowed between password changes.
# PASS_MIN_LEN Minimum acceptable password length.
# PASS_WARN_AGE Number of days warning given before a password expires.
#
PASS_MAX_DAYS 180
PASS_MIN_DAYS 7
PASS_MIN_LEN 5
PASS_WARN_AGE 10
Strangely, PASS_MIN_LEN is not used, as it is overriden by what you set minlen= to for the cracklib PAM module.
These settings say:
passwords expire after 180 days
a password must be used for at least 7 days before it can be changed again
10 days before your password will expire, you will receive a notice. The notice will pop-up in a gdm window, or at the command prompt from a virtual terminal.
These settings apply to new user accounts created with adduser, and can be viewed by using the chage -l username command.