Re: [PATCH] nice: add -a arg to set absolute niceness

[Pádraig Brady]

On 22/08/2020 02:43, Kevin Mark wrote:
> On Fri, Aug 21, 2020 at 9:14 AM Pádraig Brady wrote:
> > I'm not sure the new option is worth this simplification.
>
> Thanks for taking a look. I agree that the small shell one-liner this
> patch can replace is not particularly motivating, but I wanted to
> include it to make it clear what feature this patch was adding. The
> good news is that this patch should be strictly additive and I was not
> able to find an instance where it introduced a backcompat issue.
>
> My motivation for this patch originates from the need to set a
> specific/absolute niceness value in an environment where the shell
> alternative I mentioned is unavailable. I'm using SDDM to launch Xorg,
> and I'd like for Xorg to be launched with a niceness of -4 regardless
> of SDDM's niceness, which should be 0 but I don't want to rely on
> that. SDDM, via sddm.conf, allows me to configure the path to the Xorg
> binary and its arguments, but in this configuration file I do not have
> any mechanism to use shell logic. I can only provide a hardcoded
> string to a binary. This patch allows me to set the following in my
> SDDM config:
>
> [X11]
> ServerPath=/usr/local/bin/nice
> ServerArguments=-a -4 /usr/bin/Xorg -nolisten tcp

thanks for the concrete example. That helps.
Since this is a bit of an edge case,
would something like this suffice:

  [X11]
  ServerPath=/bin/sh
  ServerArguments=-c 'nice -n $((-4 - $(nice))) /usr/bin/Xorg -nolisten tcp'

You may need to use `env -S` if ServerArguments isn't split as required.

cheers,
Pádraig