bug#30928: no error val returned by 'nice' failure?

[L A Walsh]

Paul Eggert wrote:
> L A Walsh wrote:
> > how do you tell if the resetting of the
> > priority worked or failed?
>
> I guess you're supposed to look at stderr, which is what you did.
>
> This is the way 'nice' has behaved for quite some time, and it's what POSIX 
> specifies. We'd need a real good reason to change it, given that changing it 
> would no doubt break stuff.
---
How about a flag, like -e for 'fail on failure to change priority' and
(maybe less important or useful) '-w' to only return nice's return 
value, with the posix error message returned for called app (if error).

So, 
 nice -e --19 sleep 99
would return immediately if not root with exit status for EPERM (and
no text); sleep would not be executed.

and for -w case:

 nice -w --19 ls noexist
would return status for EPERM, and message:
ls: cannot access 'noexist': No such file or directory

Seems those would cover most possibly wants, though
the first would be enough to determine if nice is going to work.

Not an earth-shattering change, but at least it would allow
some way to check if nice is going to work or not so
one could not use it where it would fail (and not
generate an error message).

Thanks,..