97294434_Linux_useradd_Command_Examples__Option_Description
[Short Option] -b [Long Option] –base-dir BASE_DIR [Option Description] 
The default base directory for the system if -d HOME_DIR is not specified. BASE_DIR is concatenated with the account name to define the home directory. If the -m option is not used, BASE_DIR must exist. If this option is not specified, useradd will use the base directory specified by the HOME variable in /etc/default/useradd, or /home by default.
5 UNIX / Linux useradd Command Examples
Option Description