After much confusion I found a helpful old thread with this info to put in to the Terminal:

"/Applications/PureData/Pd.app/Contents/Resources/bin/pd -nogui"

But once I've opened PD without the GUI, how do I open my patch? If I just call my patch from the command line then I can't get it to open without the GUI.

@nuromantix In windows you would add an "open" command to the line you have posted so for example......

"C:\Users\David\Desktop\Pd Vanilla\pd-0.48-1.msw\pd\bin\pd.exe" -lib C:\Users\David\Desktop\dot\0.94-test3/Gem  -font-size 10 -font-face "Consolas" -nogui open "C:\Users\David\Desktop\tcl_message.pd

But you will not be able to display the patch...... as that is the point of -nogui.
David.

I don't want to see the GUI Just want the patch to run.....

Once I open PD then the command line disappears.

You are saying I can use -lib to open a patch? Will try it.

@nuromantix No...... it needs to be "/Applications/PureData/Pd.app/Contents/Resources/bin/pd -nogui open whole/path/to/patch/patch.pd"

But "open" might not be the Mac OSX command ....... or it might be correct.
David.

Thanks again!

It's -open /path/to/patch.pd

Complete list: http://puredata.info/docs/faq/commandline