97294434_Linux_useradd_Command_Examples__Option_Description
[Short Option] -f [Long Option] –inactive INACTIVE [Option Description] 
The number of days after a password expires until the account is permanently disabled. A value of 0 disables the account as soon as the password has expired, and a value of -1 disables the feature. If not specified, useradd will use the default inactivity period specified by the INACTIVE variable in /etc/default/useradd, or -1 by default.
5 UNIX / Linux useradd Command Examples
Option Description