`groupdel projectx` fails with a complaint that the group cannot be removed. The group has no supplementary members listed in /etc/group, and you are running the command as root. What is the most likely cause?
LPIC-1 Exam 102-500, objective 107. Administrative tasks hard
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How these questions are written — where each question comes from, what the verification ledger records, and what happens when one is found wrong.
The options
Correct The group is the primary group of an existing user, named in the GID field of that user's /etc/passwd line.
Correct. groupdel refuses to remove a group that is any user's primary group, precisely because the fourth field of that user's passwd line would then point at a GID with no name. Change the user's primary group with usermod -g, or remove the user first.
Not correct Files on the filesystem are still owned by the group, and groupdel scans the filesystem before deleting.
Wrong. groupdel does not scan the filesystem; deleting a group happily leaves files owned by an orphaned GID, which is why `find / -nogroup` exists. That is a consequence to clean up, not a reason for the refusal.
Not correct A group cannot be removed while a member is logged in, unless -f is given.
Wrong. That interlock exists for userdel, whose -f forces removal of an account whose owner is still logged in. groupdel has no such check on sessions.
Not correct The group's GID is below the GID_MIN value in /etc/login.defs, and system groups are protected.
Wrong. GID_MIN only bounds the range from which groupadd allocates a GID automatically. It grants no protection against deletion, and root may delete a low-numbered group.
Why
A user's primary group is recorded as a bare number in the fourth field of /etc/passwd, and nothing there would survive the name disappearing, so groupdel enforces the dependency. The supplementary memberships in the fourth field of /etc/group are a different matter: those are cleaned up as part of the deletion. The fix is to reassign the primary group first, with `usermod -g othergroup user`, and only then delete.
Where this comes from
- Cited
- manual page groupdel(8)
Practise this
Reading one question is not practice. The trainer will draw a short set from objective 107 and space the ones you get wrong.
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