The New-FileCatalog command is used to generate (or update) a catalog:

New-FileCatalog -Path <ToWatch> -CatalogFilePath <StateFile> 

A hash can only be generated for files that are larger than 0 bytes. However, filenames are recorded irrespective of the size.

The following command creates a file catalog from the files and folders created when exploring permissions:

New-FileCatalog -Path C:TempACL -CatalogFilePath C:TempSecurityexample.cat 

If the CatalogFilePath had been a directory instead of a file, New-FileCatalog would have automatically created a file named catalog.cat.