docker-plex/root/etc/cont-init.d/50-plex-update

#!/usr/bin/with-contenv bash

# set no update message
[[ -e /tmp/no-version.nfo ]] && \
        rm /tmp/no-version.nfo
NOVERSION_SET='/tmp/no-version.nfo'
cat > "${NOVERSION_SET}" <<-EOFVERSION


#######################################################
# Update routine will not run because you havent set  #
# the VERSION variable, for more information checkout #
#    https://github.com/linuxserver/docker-plex       #
#######################################################
EOFVERSION

# test for no version set or opt out for autoupdates
if [ -z "$VERSION" -o "$VERSION" == "0" -o ! -z "$ADVANCED_DISABLEUPDATES" ]; then
echo "$(cat /tmp/no-version.nfo)"
exit 0
fi

# set header for no preferences/token message
[[ -e /tmp/no-token.nfo ]] && \
	rm /tmp/no-token.nfo
NOTOKEN_SET='/tmp/no-token.nfo'
cat > "${NOTOKEN_SET}" <<-EOFTOKEN


#####################################################
#   Login via the webui at http://<ip>:32400/web    #
#   and restart the docker, because there was no    #
EOFTOKEN

# if preferences files doesn't exist, exit out
if [ ! -e "/config/Library/Application Support/Plex Media Server/Preferences.xml" ]; then
cat >> "${NOTOKEN_SET}" <<-EOFTOKEN
#   preference file found, possibly first startup.  #
#####################################################


EOFTOKEN
echo "$(cat /tmp/no-token.nfo)"
exit 0
fi

# attempt to read plex token
PLEX_TOKEN=$( sed -n 's/.*PlexOnlineToken="//p' \
	"/config/Library/Application Support/Plex Media Server/Preferences.xml" \
	| sed "s/\".*//")

# if plex token isn't found, exit out
if [ -z "$PLEX_TOKEN" ]; then
cat >> "${NOTOKEN_SET}" <<-EOFTOKEN
#      plex token found in the preference file      #
#####################################################


EOFTOKEN
echo "$(cat /tmp/no-token.nfo)"
exit 0
fi

# determine installed version of plex
INSTALLED=$(dpkg-query -W -f='${Version}' plexmediaserver)


# start update routine

[[ "$PLEXPASS" ]] && \
	echo "PLEXPASS is deprecated, please use VERSION"

if [[ -z $VERSION && "$PLEXPASS" == "1" || $VERSION = "plexpass" ]]; then echo "VERSION=plexpass is deprecated please use version latest"; fi

if [[ "$VERSION" = latest || "$VERSION" = plexpass ]]; then
	VERSION=$(curl -s "${PLEX_URL}/latest/1?channel=8&build=linux-ubuntu-x86_64&distro=ubuntu&X-Plex-Token=$PLEX_TOKEN"| cut -d "/" -f 5 )
	echo "Target version: $VERSION set to: latest\plexpass"
elif [[ "$VERSION" = public ]]; then
	VERSION=$(curl -s "${PLEX_URL}/latest/1?channel=8&build=linux-ubuntu-x86_64&distro=ubuntu&X-Plex-Token="| cut -d "/" -f 5 )
	echo "Target version: $VERSION set to: public"
else
	echo "Target version: $VERSION set to: manual"
fi

last=130
if [[ "$VERSION" != "$INSTALLED" ]]; then
 echo "Upgrading from version: $INSTALLED to version: $VERSION"
	while [[ $last -ne "0" ]]; do
	rm -f /tmp/plexmediaserver_*.deb
	curl -o /tmp/plexmediaserver_"${VERSION}"_amd64.deb -L \
		"${PLEX_URL}/plex-media-server/$VERSION/plexmediaserver_${VERSION}_amd64.deb"
	last=$?
	done
	[[ ! -e /tmp/plexmediaserver_"${VERSION}"_amd64.deb ]] && \
	exit 0
 apt-get remove --purge -y \
	plexmediaserver
 dpkg -i /tmp/plexmediaserver_"${VERSION}"_amd64.deb

else
	echo "No need to update!"
fi

cp -v /defaults/plexmediaserver /etc/default/plexmediaserver