In UNIX-like OS, the authority for a certain file varies depending on the user who uses it.
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In UNIX-like OS, the authority for a certain file varies depending on the user who uses it. Which of the following description is correct?
Show answer & explanation
UNIX file permissions follow a three-tier model: owner (user), group, and others. Each file has exactly one owner user and one owning group, with distinct permission bits (rwx) for each tier. Options A and B are incorrect because UNIX supports group and other permissions beyond just the owner. Option D is incorrect because there is only one owner and one group per file, not multiple.
Step-by-step Derivation:
UNIX file permissions are represented by 9 bits: 3 for owner (user), 3 for group, 3 for others. The ls -l output shows this as -rwxr-xr-x, where: (1) owner has rwx, (2) group has r-x, (3) others have r-x. The stat or ls command reveals each file has exactly one uid (owner) and one gid (group). This three-tier permission model allows different access levels for the owner, members of the owning group, and all other users.