This is on linux mint 17.2. I think everything is installed, but:

 bob$ jackd -r -d alsa -r 44100 -P
jackdmp 1.9.10
Copyright 2001-2005 Paul Davis and others.
Copyright 2004-2013 Grame.
jackdmp comes with ABSOLUTELY NO WARRANTY
This is free software, and you are welcome to redistribute it
under certain conditions; see the file COPYING for details
JACK server starting in non-realtime mode
Cannot lock down 82274202 byte memory area (Cannot allocate memory)
audio_reservation_init
Acquire audio card Audio0
creating alsa driver ... hw:0|-|1024|2|44100|0|0|nomon|swmeter|-|32bit
ALSA: Cannot open PCM device alsa_pcm for playback. Falling back to capture-only mode
Cannot initialize driver
JackServer::Open failed with -1
Failed to open server

isn't what I was expecting.

What do I need to do to get jack running?