I tried with and without a slash at the end, without success. I also tried rebooting my device.
I have no idea how to set environmental variables, I'm quite new to Ubuntu.
Thanks
If you are worried about : Please set PLAYDATE_SDK_PATH env value to the SDK path, a quick read of setup.sh shows that the script prints this line in all cases. So if you have set the variable correctly, there is nothing to worry about !