You want to confirm the nice value that a running process is actually using, and you would rather not learn a field list by heart. Which ps invocation shows a NI column by default?
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 ps -l
Correct. The long format includes the PRI and NI columns, so the nice value is visible without naming any output fields.
Not correct ps -f
Wrong. The full format shows UID, PID, PPID, C, STIME, TTY, TIME and CMD, but no nice value.
Not correct ps aux
Wrong. The BSD user-oriented format shows %CPU, %MEM, VSZ, RSS and STAT, but no NI column; a low-priority process is only hinted at by an N flag inside STAT.
Not correct ps -e
Wrong. -e is a selection option, not a format one; on its own it produces the default four columns PID, TTY, TIME and CMD.
Why
In ps, selection options decide which processes appear and format options decide which columns do. -l is the long format and is the quickest way to see PRI and NI; the explicit alternative is a field list such as `ps -eo pid,ni,comm`. top shows the same value in its NI column, and its PR column shows the resulting kernel priority, which is derived from the nice value rather than set by it.
Where this comes from
- Cited
- manual page ps(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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