создать нового пользователя или обновить информацию о новом пользователе по умолчанию (create a new user or update default new user information)
Описание (Description)
When invoked without the -D option, the useradd command creates a
new user account using the values specified on the command line
plus the default values from the system. Depending on command
line options, the useradd command will update system files and
may also create the new user's home directory and copy initial
files.
By default, a group will also be created for the new user (see
-g, -N, -U, and USERGROUPS_ENAB).
