The shttpd-optenv
patch makes shttpd treat the $ROOT,
$UID, and $GID environment variables as
optional: if they are not set, the programs continue to run with their
original root directory, user ID, and group ID. This is necessary for
non-root users who want to run their own servers, and for CGI programs
that need access to the entire filesystem or that run with the ID of a
user who authenticates over the HTTP connection. The variables can be
set independently; e.g., $UID and $GID can
be set without also setting $ROOT.