systemsetup outputs should be displayed on error

[wooseopkim]

Summary

Currently, it seems that systemsetup results are redirected into /dev/null. This leads to systemsetup error messages being entirely hidden.

Context

Personally I've had some trouble because I tried to set power.sleep.computer = 240;. That is identical to systemsetup -setComputerSleep 240, which obviously fails because The time specified must be between 0 and 180 minutes(the actual error message from the command). The activation script sets -e, and as the output gets redirected like &> /dev/null, I didn't even notice that something's gone wrong after I darwin-rebuild switched. I spent hours, days, finally figuring out what actually happened. It would be significantly helpful to other users too to let the error message displayed at least on non-zero codes.

Potential fixes

I've come up with two instant ideas.

1. Don't redirect at all

I guess the rationale behind the redirection was not to overwhelm the user with excessive outputs. Given that, I don't think this would be the best idea, but at least it's simple, easy, and resolves the issue addressed here.

2. Keep outputs somewhere and display them on errors

Something like:

tmp="$(mktemp)"
if ! do_something &>"${tmp}"; then
  cat "${tmp}" >&2
  exit 1
fi

This is way longer and more complex than do_something &>/dev/null. Is this the best fix? Is it good at all? I don't know. If somebody somehow fixes this, I'm more than happy to see this resolved. I'd very much appreciate if Co-authored-by would be a good fit.

Range of the issue

GitHub search currently shows me 9 files to be using the redirection. I'm not very sure how many of them should be fixed.