The daemon(8) -u option should set USER, HOME and SHELL environment variables

[sobomax]

Summary

Unlike what su, jexec, sudo etc while running program under specific user, the daemon(8) does not set USER, HOME and SHELL environment variables just leaving them be at their current values. This is probably not what user expects in such situation.

Current behavior:

$ sudo daemon -u nobody printenv; sleep 1
[...]
USER=root
HOME=/root
SHELL=/bin/sh
[...]

Test Plan

Expected behavior:

$ sudo daemon -u nobody printenv; sleep 1
USER=nobody
HOME=/nonexistent
SHELL=/usr/sbin/nologin

[gbe]

LGTM, and thanks for finding this bug.