Неправда ваша, root писать абсолютно необязательно.
Код:
SU(1) SU(1)
NAME
su - Change user ID or become super-user
SYNOPSIS
su [-] [username [args]]
DESCRIPTION
su is used to become another user during a login session. Invoked without a
username, su defaults to becoming the super user. The optional argument - may
be used to provide an environment similiar to what the user would expect had the
user logged in directly.
