what is a uid file?
<answer> Unix-like operating systems, that identify a user within the kernel by a value called a user identifier. <context> From Wikipedia, the free encyclopedia. Unix-like operating systems identify a user within the kernel by a value called a user identifier, often abbreviated to user ID or UID. The UID, along with the group identifier (GID) and other access control criteria, is used to determine which system resources a user can access. The password file maps textual user names to UIDs, but in the kernel, only UIDs are used.