gsdlhome is read in twice.

The first is very early in the main() function in
src/recpt/librarymain.cpp. The line "cservers = new
collectset(gsdlhome);" calls the constructor for the
collectset class (src/colservr/collectset.cpp) which reads
in the gsdlsite.cfg file. It needs to do so here so it can
locate the gsdl/collect directory, find what collections are
available and assign collection servers etc.

The second time gsdlsite.cfg is read is in the cgiwrapper()
function in src/recpt/cgiwrapper.cpp.

Both times gsdlsite.cfg is read by one of the two
site_cfg_read() functions in src/recpt/recptconfig.cpp.
These are the functions you probably need to alter if you
want to try to determine the value of gsdlhome dynamically.

Hope this helps.
Stefan.