Manually running Plex Media Scanner on Linux requires the PLEX_MEDIA_SERVER_APPLICATION_SUPPORT_DIR environment variable to be set (at least in my experience). By default on Linux (using the native package) it should be set to “/var/lib/plexmediaserver/Library/Application Support.” Something like the following should work:
PLEX_MEDIA_SERVER_APPLICATION_SUPPORT_DIR="/var/lib/plexmediaserver/Library/Application Support" /usr/lib/plexmediaserver/Plex Media Scanner --analyze-deeply --force --item item_id
You can try running without --force, but in my experience the scanner will return immediately without performing analysis if not included.
