Posting this here if someone else runs into it… 
I’ve set up our “Test Driver” machine to execute a Ruby script that in turn kicks off an eggplant master. My scripts run just fine in the GUI client. However, when I execute them via the Ruby on the test machine, I get:
EggplantTD:~/EggplantScripts/Test_Suite/Notation eggplantTD$ ruby -x TestAutomation.rb PrintMusic.suite/Scripts/PrintMusicFull.script
Updating from Perforce...
File(s) up-to-date.
Executing tests...
2007-08-20 16:09:27.045 runscript[289] {snipped to protect the innocent}
2007-08-20 16:09:27.045 runscript[289] Browsing For Bonjour RFB Servers
2007-08-20 16:09:27.046 runscript[289] Listening For Reverse Connections on Port 5500
2007-08-20 16:09:28.090 runscript[289] Error Running Script Command:
opensuite Error - Unable To Open Suite ~/Documents/Entry_Group/SUT_Start.suite
2007-08-20 16:09:29.091 runscript[289] Completed EggplantTestScript Notaton.suite - Full.script
It appears that the script is not paying attention to relative paths for OpenSuite. Is there a way around it?
The OpenSuite command uses the following search precedence when called with a path that isn’t absolute:
[list]
1-Looks for a sibling suite of the current suite
2-Looks in the user’s Default Suite Directory (set in general preferences)
[/list:u]
So in particular if you are calling from a different account you will want to ensure that your Default Suite Directory is set.
That was it, Jonathan. The default suite wasn’t set in preferences on the test driver machine. A quick trip to Property List Editor did the trick. For anyone interested, simply add a string key called DefaultDocumentDirectory with the value of the folder you want to use in com.redstonesoftware.Eggplant.plist.
The entry is called DefaultDocumentDirectory in com.redstonesoftware.Eggplant.plist – but usually the easier way to set it is using the field at the bottom of the General Preferences pane in Eggplant (where it is labelled Default Suite Directory).
Unless, of course you have a CLI-Only licence on a lab machine, then the only way to do it is to edit the PLIST. Thanks for catching my mis-type. I shouldn’t post right before lunch 
No problem, and of course you’re right, if you can’t run the GUI version of Eggplant on that machine (or account) then the preference pane doesn’t do you much good.
Instead of using Property List Editor (not everyone has it, I believe) you can also do this in a terminal window (when logged in under the account that will be running the script):
defaults write com.redstonesoftware.Eggplant DefaultDocumentDirectory /path/to/desired/directory
(Note: that’s a single command, in case it’s wrapped on your screen)