Re: prenice(1) problem? Or pilot error?

[Paul Goyette <paul%whooppee.com@localhost>]

On Mon, 18 Apr 2016, Ian D. Leroux wrote:

> On Mon, 18 Apr 2016 08:15:58 +0800 (PHT) Paul Goyette
> <paul%whooppee.com@localhost> wrote:
> > But when I try to prenice(1) those processes, I get no results:
> >
> >  	# prenice -l 20 -g 20012
> >  	#
> >
> > Shouldn't I expect prenice(1) to show me which processes are being
> > affected?  And shouldn't that list match the list from pgrep(1)
> > (modulo any processes which may have been newly created or exited)?
>
> Well, the usual rule is to be silent on success, so I wouldn't
> expect any output from prenice(1) if it did what you asked, any more
> than pkill(1) outputs the names of the processes it killed.  What's the
> exit code?
>
> That said, the manpage is a little confusing, since it tries to
> describe the behaviour of pgrep(1) (which must of course give output)
> alongside prenice(1) and pkill(1)(which shouldn't, unless something
> goes wrong).

The synopsis explicitly lists -l for prenice, and the text says that it 
produces more detailed info than without the option.  I would therefore 
assume that

1. there is some minimal output without the option, and
2. there is more-than-minimal output with the option.

:)

In any case, I was able to get what I really wanted by

	#  pgrep -g 20012 | xargs renice 20 -p
	15415: old priority 20, new priority 20
	5031: old priority 20, new priority 20
	1964: old priority 20, new priority 20
	7111: old priority 20, new priority 20
	23969: old priority 20, new priority 20
	577: old priority 20, new priority 20
	6604: old priority 20, new priority 20
	4187: old priority 20, new priority 20
	28804: old priority 20, new priority 20
	6691: old priority 20, new priority 20
	16959: old priority 20, new priority 20
	14794: old priority 20, new priority 20
	18504: old priority 20, new priority 20
	20012: old priority 20, new priority 20
	#


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