The Linux files involved when creating a user are:

/etc/passwd: This file stores basic user information such as the user's home directory, default shell, and login name.

/etc/shadow: This file stores the user’s encrypted password for authentication.

/etc/gshadow: This file stores group password information and other related data.

/etc/group: This file lists the user's group membership.

 /etc/login.defs file defines the site-specific configuration for the shadow password suite. This file is required. Absence of this file will not prevent system operation, but will probably result in undesirable operation


/etc/sudoers: This file defines which users are allowed to run sudo or superuser commands and with what privileges.

/etc/skel : This directory stores default settings and configuration files to be used when creating a new user.

/etc/bashrc: This file holds global bash settings, such as the default editor, prompt, aliases, and other environment variables

/etc/default/useradd: This file defines the default values and settings used by the useradd command when creating a new user."