@User: If you use the .magicrc startup file that is installed with open_pdks, which is highly recommended, then it sets the $SUB variable so that it does not end up with the "$" in the netlist output and cause problems with ngspice. But what you want is to run a command like "set SUB VSUBS" or something like that in your .magicrc startup script. This assigns a name to the variable $SUB so that the variable name doesn't end up in the netlist.