While watching top you decide that a running process should be given a less favourable nice value, without leaving top. Which interactive key starts that operation?
LPIC-1 Exam 101-500, objective 103. GNU and Unix commands 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
Correct r
Correct. r prompts for a PID and then for a nice value, and applies it exactly as renice would.
Not correct k
Wrong. k prompts for a PID and a signal and sends it, which terminates rather than reprioritises.
Not correct n
Wrong. n sets the number of tasks top displays; it does not touch any process.
Not correct P
Wrong. P re-sorts the display by %CPU. Sorting changes the view, not the scheduling of anything.
Why
top exposes the two most common process interventions directly: k to send a signal and r to renice. Both prompt for the PID first, defaulting to the process at the top of the list, so it is worth reading the prompt before pressing Enter. The same rules as the command line apply inside top: an unprivileged user may only raise a nice value, and only for their own processes.
Where this comes from
- Cited
- manual page top(1)
Practise this
Reading one question is not practice. The trainer will draw a short set from objective 103 and space the ones you get wrong.
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