Create users in bulk
------tom joy mark
------Password redhat
------vi /app/user.sh edit script execution
-----useradd
Change user password
Delete users and groups
-----userdel -r username
Create user group sysmgrs
User natasha/harry, subordinate to sysmgrs as a secondary group
User sarah does not have access to the system
Batch change user passwords
Natasha, harry, sarah batch change user passwords to 123
------ vi /app/user.sh
-----#！/bin/bash
