compiz --replace -c emerald
Checking for Xgl: not present.
Detected PCI ID for VGA: 01:00.0 0300: 10de:01d3 (rev a1) (prog-if 00 [VGA])
Checking for texture_from_pixmap: present.
Checking for non power of two support: present.
Checking for Composite extension: present.
Comparing resolution (1280x1024) to maximum 3D texture size (4096): Passed.
Checking for nVidia: present.
Checking for FBConfig: present.
Checking for Xgl: not present.
Starting emerald
/usr/bin/compiz.real (core) - Warn: Unknown option '-c'
/usr/bin/compiz.real (core) - Error: Couldn't load plugin 'emerald'
/usr/bin/compiz.real (dbus) - Error: dbus_bus_get error: Failed to execute dbus-launch to autolaunch D-Bus session
/usr/bin/compiz.real (core) - Error: Couldn't activate plugin 'dbus'
/usr/bin/compiz.real (video) - Warn: No 8 bit GLX pixmap format, disabling YV12 image format