How to run the WRF-CROCO coupling model?

I set up the file according to the wrf-croco coupling in the manual( But there are the following errors, how to solve it?
./ line 36: DT_OCE: unbound variable

Another question is how do I determine the ${MACHINE} option?And, is there any documentation for these variables?

The MACHINE variable allows to automatically set up some environment variables and job submission instructions for know machines. The are a few known machines already included: classical Linux and some super-computers. But you can add your own MACHINE set up by adding a directory in SCRIPTS_TOOLBOX/MACHINE.

Check the existing machines, and create a similar directory for your own machine with the same scripts inside (e.g. header.Linux,, myenv.Linux, myenv.Linux.wrf, myenv.Linux.ww3, with Linux changed to your machine name). You obviously need to adapt these scripts to your machine.