Erni replaces "su {user} -c {command}" that root uses to
run commands as nonroot users, because this method
requires that {user} have a valid login shell, leaving
another avenue open to abuse the account. With Erni,
{user} need not have a valid login shell, {user}'s group
memberships may be specified on the command line, and
{command} may be chroot'd. It may be used to kick off
daemons and also to run interactive tools (e.g. an SQL
browser) as the target user.
