gnetlist -g spice-sdb -o out.spice rlc.sch
Your file generated the following netlist:
* gnetlist -g spice-sdb -o out.spice rlc.sch
*********************************************************
* Spice file generated by gnetlist *
* spice-sdb version 5.16.2005 by SDB -- *
* provides advanced spice netlisting capability. *
* Documentation at http://www.brorson.com/gEDA/SPICE/ *
*********************************************************
V1 2 3 6V
L1 1 3 10uH
R1 2 1 17
C1 3 1 5nF
.END
which looks like a valid spice netlist to me.
http://www.brorson.com/gEDA/SPICE/t1.html
This link really includes all the information that you need to go
from schematic to netlist to simulating your design.
-Ales