When defining a Request Set parameter, I would like to know if I can combine constant text with a sh

I have defined a request set and am setting parameter defaults using shared parameters.  One of my shared parameters requires constant text (e.g., file path) and the value of a shared parameter from the previous stage (e.g. filename).  The result I would like is a concatenated value of both the constant text (e.g., "/p01/tmp/") and the shared parameter (e.g., "filename.txt") - final result would be "p01/tmp/filename.txt".  Is this possible?