I've just solved a problem that's taken me a while to get my head around, so I thought I'd post the result here. It's probably not news to may, but hopefully, it will help some.
The 'issue' was around paths used by PSOS, BE_ExportFieldContents and ImportRecords. I needed to grab a csv file of customer details from a container field and import it into the the customer table. I wanted to do this as a PSOS because it was going to be much faster. It needed to run in a Windows and MacOS environment.
Server side scripts can only access files in two locations :- The Temp folder and the Documents Folder. More details here.
I wanted to use the Temp Folder because, "In server-side scripts, each script runs in its own session; once the script is completed, the session terminates and the temporary folder is deleted." Help article here.
BE_ExportFieldContents uses OS file paths - FM file paths will not work. Reference here.
These are the script steps that gave me the result I needed.