useradd : create a new user
[SYNOPSIS] useradd OPTION USER
OPTION
-b BASE_DIR base directory for the home directory of the new account
-c COMMENT GECOS field of the new account
-d HOME_DIR home directory of the new account
-D print or change default useradd configuration
-e EXPIRE_DATE expiration date of the new account
-f INACTIVE password inactivity period of the new account
-g GROUP name or ID of the primary group of the new account
-G GROUPS list of supplementary groups of the new account
-h display help message and exit
-k SKEL_DIR use this alternative skeleton directory
-K KEY=VALUE override /etc/login.defs defaults
-l do not add the user to the lastlog and faillog databases
-m create the user's home directory
-M do not create the user's home directory
-N do not create a group with the same name as the user
-o allow to create users with duplicate (non-unique) UID
-p PASSWORD encrypted password of the new account
-r create a system account
-R CHROOT_DIR directory to chroot into
-P PREFIX_DIR prefix directory where are located the /etc/* files
-s SHELL login shell of the new account
-u UID user ID of the new account
-U create a group with the same name as the user
-Z SEUSER use a specific SEUSER for the SELinux user mapping