I get the exact same problem with rhythmbox-client --play and several other options (--pause, --play-pause, etc.) on my Precise install.
Interestingly enough, rhythmbox-client --notify seems to be an exception of sorts; it still refuses to work, but returns instead: Rhythmbox-WARNING **: Unknown option --notify ...despite --notify being listed in the man page. (If that's a separate issue, let me know and I'll file a new report for it.) -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to rhythmbox in Ubuntu. https://bugs.launchpad.net/bugs/950743 Title: rhytmbox-client commands are not working Status in “rhythmbox” package in Ubuntu: Confirmed Bug description: with rhytmbox running if I try rhytmbox-client --play I get: Rhythmbox-WARNING **: MPRIS D-Bus interface not available, some things won't work ProblemType: Bug DistroRelease: Ubuntu 12.04 Package: rhythmbox 2.95-0ubuntu3 ProcVersionSignature: Ubuntu 3.2.0-15.24-generic-pae 3.2.5 Uname: Linux 3.2.0-15-generic-pae i686 ApportVersion: 1.94-0ubuntu2 Architecture: i386 Date: Fri Mar 9 12:18:58 2012 DistributionChannelDescriptor: # This is a distribution channel descriptor # For more information see http://wiki.ubuntu.com/DistributionChannelDescriptor canonical-oem-dell-maverick-une-20101010-0 EcryptfsInUse: Yes ExecutablePath: /usr/bin/rhythmbox InstallationMedia: Ubuntu 10.10 "Maverick" - Build i386 LIVE Binary 20101010-01:50 ProcEnviron: SHELL=/bin/bash PATH=(custom, user) LANG=en_US.UTF-8 SourcePackage: rhythmbox UpgradeStatus: Upgraded to precise on 2012-02-09 (29 days ago) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/rhythmbox/+bug/950743/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp