I know my device is supported but plexupdate says no
Caveat
Plexupdate is wholly dependent on the platforms that the official plex developers decide to support, we cannot help with that. Also take care when choosing DISTRO and BUILD manually so it is indeed supported by your device. Just because something has the right keywords in the name, it doesn't necessarily mean that it will work.
https://forums.plex.tv is a great place to start when you're unsure or wondering if your device is supported.
How to override detection
In some cases, plexupdate cannot properly detect the OS and/or distribution of the device you're running. To avoid causing issues by selecting "best effort" package, plexupdate will exit with a message like this:
ERROR: Plex Media Server on Raspbian is not officially supported and script cannot download a working package.
But if you know what package to install, you can tell plexupdate what to do. To get a list of supported packages (this is pulled from https://plex.tv) you issue ./plexupdate.sh -l which should result in a list similar to this:
DISTRO BUILD DESCRIPTION
====== ===== ==============================================
asustor linux-armada-arm7 ARMv7
asustor linux-ubuntu-i686 Intel 32-bit
asustor linux-ubuntu-x86_64 Intel 64-bit
qnap linux-annapurna-arm7 ARMv7-X31+/X31P/X31X/1635
qnap linux-debian-i686 Intel/AMD 32-bit (QTS-4.2.x or older)
qnap linux-qnapx31-armv7 ARMv7-X31
qnap linux-ubuntu-x86_64 Intel/AMD 64-bit (QTS-4.3 or newer)
readynas6 linux-annapurnatrans-arm7 ARM 6.x RN2xx
readynas6 linux-armada-arm7 ARM 6.x
readynas6 linux-ubuntu-x86_64 Intel 6.x
redhat linux-ubuntu-i686 CentOS 32-bit (RPM for CentOS 6 or newer)
redhat linux-ubuntu-i686 Fedora 32-bit (RPM for Fedora 14 or newer)
redhat linux-ubuntu-x86_64 CentOS 64-bit (RPM for CentOS 6 or newer)
redhat linux-ubuntu-x86_64 Fedora 64-bit (RPM for Fedora 14 or newer)
seagate linux-seagate-arm7 ARMv7
seagate linux-ubuntu-seagate-x86_64 Intel x64
synology linux-synology-armv7 ARMv7
synology linux-synology-i686 Intel - 32-bit
synology linux-ubuntu-x86_64 Intel - 64-bit (DSM +6.0)
thecus linux-ubuntu-i686 Intel 32-bit OS6
thecus linux-ubuntu-x86_64 Intel 64-bit
ubuntu linux-ubuntu-i686 Ubuntu 32-bit (10.04 Lucid or newer)
ubuntu linux-ubuntu-x86_64 Ubuntu 64-bit (10.04 Lucid or newer)
unraid linux-ubuntu-x86_64 64-bit
wd-dl2100 linux-ubuntu-x86_64 My Cloud DL2100
wd-dl4100 linux-ubuntu-x86_64 My Cloud DL4100
wd-ex2100 linux-wd-armv7 My Cloud EX2100
wd-ex2 linux-wd-armv7 My Cloud EX2
wd-ex2ultra linux-wd-armv7 My Cloud EX2 Ultra
wd-ex4100 linux-wd-armv7 My Cloud EX4100
wd-mirrg2 linux-wd-armv7 My Cloud Mirror Gen2
wd-mirr linux-wd-armv7 My Cloud Mirror
wd-pr2100 linux-ubuntu-x86_64 My Cloud PR2100
wd-pr4100 linux-ubuntu-x86_64 My Cloud PR4100
Notice the two first columns, DISTRO and BUILD. Find the package you desire and make a note of the corresponding values in the DISTRO and BUILD. For this example, we'll pick readynas6 and linux-annapurnatrans-arm7 (for the ARM 6.x RN2xx flavor).
Next, open /etc/plexupdate.conf and add two lines like so:
DISTRO='readynas6'
BUILD='linux-annapurnatrans-arm7'
Finally, re-run plexupdate.sh and it should now try to download and install your selected package.
But plexupdate is using the wrong method to install my package!
Don't worry, there is a third option you can set called DISTRO_INSTALL, this should be set to whatever command and parameters needed to install the downloaded package. By default it should be able to detect and deal with .rpm and .deb. but by adding a third line to /etc/plexupdate.conf with your desired package manager, plexupdate will use that instead. For example:
DISTRO_INSTALL='/bin/false --some --options'
will cause plexupdate.sh to run /bin/false --some --options downloaded_package_file to install your package.
Just make sure you provide a full path to the tool so it can be properly executed.