Current Gentoo installation instructions don't work and can break existing overlays

[lembark]

The instructions include:

echo "PORTDIR_OVERLAY=$PORTDIR_OVERLAY /usr/local/portage/overlays" >> /etc/make.conf

(1) The file has been moved to /etc/portage/make.conf. Even if this file exists on older systems it is no longer used (unless it's a symlink to ./portage/make.conf).

(2) If there is already an existing PORTDIR_OVERLAY this will break the working system by replacing it with a new one.

A better approach would be:
. /etc/portage/make.conf;
if [ -n "$PORTDIR_OVERLDAY" ]
then
# append whatever you like to the file, or better yet, insert it near the top
# where any existing definitions are already defined.
else
# install into $PORTDIR_OVERLAY
fi

However you like it, the path to make.conf needs to be updated for the instructions to work and some check for an existing PORTDIR_OVERLAY is necessary to avoid breaking existing installations.

[vozhyk-]

A better way is to make it possible to add the overlay with layman. As far as I know, it only requires an xml file.
A layman description file is present. So the instructions can be updated to use layman to add the overlay.

[vozhyk-]

Also, there is an ebuild for dev-java/sbt (not -bin) in portage, it just needs to be updated to 0.13.9 (it's 0.13.8 currently).