Final answer:
GID, UID, and EUID in Unix-based systems stand for Group Identifier, User Identifier, and Effective User Identifier, serving as a way to manage permissions and access control based on user IDs and group membership.
Step-by-step explanation:
The acronyms GID, UID, and EUID stand for Group Identifier, User Identifier, and Effective User Identifier, respectively. These terms are commonly used in Unix-based operating systems to manage permissions and access control.
The UID is a unique number assigned to each user, identifying them to the system. The GID is a number that corresponds to a user group, which is like a category that can include multiple users, all of which inherit the group's permissions.
The EUID is the identifier actually used by the operating system to determine access to resources; it typically starts as the UID of the user who initiated a process and can be changed by the process if it has the appropriate permissions (e.g., a program that has been granted 'setuid' status).