Hi there
I have attached the a simple scene to illustrate my problem.

I am attempting to write a file with a filename copied from a parameter that uses python to generate the filename.

In the attached scene the parameter produces ‘$HIP/pythonTest.bgeo’

When I paste relative the reference using `chs(“../parm”)` I get an error saying on the file node saying “unable to read file ‘$HIP/pythonTest.bgeo’”

If I manually type this in or copy it from a parameter that I type it into it works fine, so I know it has to do with resolving the “HIP…” filename into a full path but I don't know what command I can use to do this.

Thanks a lot

Mat