A single report must be generated once, at 22:00 tonight, and never again. Which approach fits best?
LPIC-1 Exam 102-500, objective 107. Administrative tasks medium
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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
Not correct Add a crontab entry `0 22 * * *` and remember to delete it tomorrow
Wrong as a design. cron schedules are recurring by nature, so this runs every night until a human remembers to remove it. Relying on that memory is exactly the failure mode that at exists to avoid.
Correct `at 22:00` and type the command at the at> prompt
Correct. at queues a command for one single execution at a given time, then discards the job. Times may be absolute (22:00, midnight, teatime) or relative (now + 2 hours).
Not correct Put the script in /etc/cron.daily
Wrong. Scripts under /etc/cron.daily are run once per day, every day, at a time chosen by the system (via run-parts or anacron). That is recurring, and you do not control the hour.
Not correct Add an entry to /etc/anacrontab
Wrong. anacron exists to run periodic jobs that were missed while a machine was switched off. Its schedule is a period in days, not a wall-clock time, and it is still recurring.
Why
at handles one-off jobs and needs the atd daemon running. `atq` lists the queue with job numbers, `atrm N` (equivalently `at -d N`) deletes a queued job, and `at -c N` shows the full environment and commands of a job. Access is controlled by /etc/at.allow and /etc/at.deny, the same way cron uses /etc/cron.allow and /etc/cron.deny.
Where this comes from
- Cited
- LPI exam objective 107.2
- What it says
- Use at to schedule a job for one-off execution at a specific time.
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.
More questions on this objective
- The account alice already belongs to the supplementary groups audio and video. You must additionally put her in the group developers while keeping her existing memberships. Which command does that? machine-checked
- A departing employee's account bob must be deleted together with his home directory and mail spool. Which command does all of that in one step? machine-checked
- You want every newly created account to start with a company-standard .bashrc already in its home directory. Where do you place that file? machine-checked
- On a host whose accounts come partly from local files and partly from a directory service, `grep alice /etc/passwd` returns nothing even though `id alice` works. Which command shows alice's account entry the way the system itself resolves it? machine-checked
- Policy says passwords must be changed at least every 90 days, and the account carol must comply. Which command sets that maximum password age? machine-checked
- A line in /etc/group reads `developers:x:1500:alice,bob`. What does the final field contain? machine-checked