A team lead who has no root access must be able to change who receives mail sent to the address oncall, without an administrator being involved each time. Which /etc/aliases entry gives them that, assuming the lead owns the referenced file?
LPIC-1 Exam 102-500, objective 108. Essential system services hard
Machine-checked — no person has signed for it. This question was read against the source cited below by an automated pass, which found no contradiction. That is a weaker claim than it sounds: the same kind of process wrote the question, so it can confirm its own mistake.
Treat it as a good draft rather than as settled fact, and read the source below before you rely on it. It is not used in mock exams here — only questions a person has signed for are.
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 oncall: :include:/var/lib/oncall/members
Correct. The :include: form makes the delivery agent read the recipient list out of the named file at delivery time, so whoever can write that file controls the membership.
Not correct oncall: /var/lib/oncall/members
Wrong. A plain absolute path is a delivery destination: every message to oncall would be appended to that file in mbox format instead of being sent on to people.
Not correct oncall: |cat /var/lib/oncall/members
Wrong. The pipe form feeds the message to the command's standard input; the command's output is not interpreted as a recipient list. The message would simply be discarded into cat's output.
Not correct oncall: \oncall, /var/lib/oncall/members
Wrong. A leading backslash suppresses further expansion and forces delivery to a local user of that name, and the second element is again a file to append to. Neither reads a recipient list.
Why
The key difference is when each construct is read. The aliases file itself is compiled into an indexed database and only takes effect after that database is rebuilt, whereas an :include: file is opened and parsed on every delivery, so edits to it apply at once and need no administrative step. That is exactly why :include: is the standard way to delegate a mailing list to a non-root owner.
Where this comes from
- Cited
- manual page aliases(5)
Practise this
Reading one question is not practice. The trainer will draw a short set from objective 108 and space the ones you get wrong.
More questions on this objective
- You corrected the running system's clock with `date -s`, but after the next power cycle the machine came back with the old wrong time. Which command copies the corrected system clock into the hardware (RTC) clock? machine-checked
- On a systemd-based distribution, which file determines the local time zone used by the C library when formatting times? machine-checked
- A host runs chrony as its NTP client. Which command shows the list of time sources chrony is currently talking to and how it rates each one? machine-checked
- In /etc/ntp.conf you find the line `server 0.pool.ntp.org iburst`. What does the `iburst` keyword do? machine-checked
- A minimal systemd host synchronises its clock with systemd-timesyncd. Which statement about that service is accurate? machine-checked
- On a systemd host, type the single command that turns on automatic network time synchronisation (do not include a path). machine-checked