Support for defining uid and guid during rpm installation

It would be nice if system administrators could set user and group during installation. This could be realized as either

export RUN_AS_USER=application1User
export RUN_AS_GROUP=applicationGroup

or with parameters to the rpm installation command.

My current workaround is:

if [ "$RUN_AS_USER" = "" ]; then
echo Variable RUN_AS_USER not set, defaulting to root.
export RUN_AS_USER=root
fi
echo Changing ownership according to RUN_AS_USER=$RUN_AS_USER
chown -Rc $RUN_AS_USER $RPM_INSTALL_PREFIX
echo chmod ug+x on directories in $RPM_INSTALL_PREFIX
find $RPM_INSTALL_PREFIX -type d -exec chmod -c ug+x {} \;

The variable RUN_AS_USER was chosen because this variable is read by Java Service Wrapper scripts generated with appassembler-maven-plugin.